Spatial Layout of Cotton Seed Production Based on Hierarchical Classiﬁcation: A Case Study in Xinjiang, China

: Cotton seed production is the main form of agriculture in Xinjiang, China. Unreasonable distribution of cotton seed production results in a waste of water, land, and human resources. In this study, we established a hierarchical classiﬁcation integrating method; investigated the spatial suitability of climate, land and water resources, and infrastructure; examined the production risk and planting history; and integrated spatial suitability and production risk and history to produce the spatial layout of seed production for early-maturing cotton (EMC), early–medium-maturing cotton (EMMC), and long staple cotton (LSC) in Xinjiang. The results indicated that the appropriate areas for EMC, EMMC, and LSC seed production are 6.4 × 10 5 , 5.5 × 10 5 , and 3.6 × 10 5 ha, respectively. By combining the suitable areas of seed production for the three cotton species, we concluded that the superior and most suitable area for producing cotton seed of EMC, EMMC, or LSC is located in the western Tarim Basin. The sub-suitable area for cotton seed production of EMC, EMMC, or LSC is mostly distributed in the western and northern Tarim Basin. This research provides a good solution to the selection of cotton seed production base; however, adoption will depend on the actual preference and market factors.


Introduction
Cotton, an important source of natural fibers to textile industries around the world, is widely planted in more than 70 countries [1,2]. As a key constituent of cotton production and raw cotton consumption in the world, China accounts for one-quarter of the world's cotton output and one-third of the world's cotton consumption [3], and the quantity and quality of China's cotton production will have a significant impact on the global cotton industry. Due to sufficient light, abundant heat, suitable soil, and water conditions, the breeding of new cotton varieties with high yield and insect resistance, advanced watersaving irrigation technology, and related policies, Xinjiang, with a long history of cotton planting, has become the center of cotton planting in China, contributing nearly 84% of the total production in China in 2018 [4,5]. Compared with 2017, the cotton area in 2018 increased by 210,300 ha, the annual planting area remained at 2.4 to 2.667 million hectares, and the annual cotton seed demand was between 80,000 and 100,000 tons [6]. In regard to whether Xinjiang can continue to play its key role in the industry of cotton in the future, the development of the cotton seed industry is particularly important. The regional distribution optimization of cotton seed production based on regional resources is essential to the development of the seed industry in Xinjiang [7].

Data Collection and Processing
The dataset used in this study mainly included meteorological data, soil and water resource data, and statistical data. Based on the literature, expert knowledge, and the actual situation in Xinjiang, we obtained the key indicators and threshold values of cotton seed production in the area. In addition, the climate index, the soil and water conditions, the socioeconomic conditions, and the production risk conditions of the three types of cotton in the study area were divided into the same criteria (Table 1).

Meteorological Data
The average daily temperature from 1980 to 2018 was extracted to calculate the active accumulated temperature equal to or greater than 10 °C (AAE_10) (Formula (1)), the active accumulated temperature greater than 15 °C (AAE_15) (Formula (2)), the average temperature in July and August (AT_JA), and the duration in days of temperature equal to or greater than 15 °C (DD_15) (Formulas (3)-(5)). The daily minimum temperature from 1980 to 2018 was used to calculate the frost-free period (FFP). Taking the daily minimum temperature equal to or greater than 2 °C as the index of frost days, the duration between the last frost day and the first frost day is the frost-free period, and the calculation of first and last frost days is the same as Dstart and Dend of DD_15. The maximum daily temperature from 1980 to 2018 was used to calculate the duration in days of temperature equal to or greater than 35 °C (DD_35), and the method was same as that of DD_15. Sunshine hours

Data Collection and Processing
The dataset used in this study mainly included meteorological data, soil and water resource data, and statistical data. Based on the literature, expert knowledge, and the actual situation in Xinjiang, we obtained the key indicators and threshold values of cotton seed production in the area. In addition, the climate index, the soil and water conditions, the socioeconomic conditions, and the production risk conditions of the three types of cotton in the study area were divided into the same criteria (Table 1).

Meteorological Data
The average daily temperature from 1980 to 2018 was extracted to calculate the active accumulated temperature equal to or greater than 10 • C (AAE_10) (Formula (1)), the active accumulated temperature greater than 15 • C (AAE_15) (Formula (2)), the average temperature in July and August (AT_JA), and the duration in days of temperature equal to or greater than 15 • C (DD_15) (Formulas (3)-(5)). The daily minimum temperature from 1980 to 2018 was used to calculate the frost-free period (FFP). Taking the daily minimum temperature equal to or greater than 2 • C as the index of frost days, the duration between the last frost day and the first frost day is the frost-free period, and the calculation of first and last frost days is the same as D start and D end of DD_15. The maximum daily temperature from 1980 to 2018 was used to calculate the duration in days of temperature equal to or greater than 35 • C (DD_35), and the method was same as that of DD_15. Sunshine hours from 1980 to 2018 were used to calculate the sunshine rate from April to October (SR_AO) and annual sunshine hours (ASH). Daily precipitation from 1980 to 2018 was used to calculate precipitation from September to October (Pre_SO).
The inverse distance weighted (IDW) method was adopted to interpolate AAE_10, AAE_15, AT_JA, DD_15, FFP, DD_35, SR_AO, ASH, and Pre_SO into a raster surface at 30-m spatial resolution. Then, according to the threshold value given in Table 1, the grid of  AAE_10, AAE_15, AT_JA, DD_15, FFP, DD_35, SR_AO, ASH, and Pre_SO were reclassified to obtain the suitable and the unsuitable area of each index.
Active accumulated temperature where n is days of the cotton growing period. Suppose T is the average daily temperature; when T is less than 10, T i is equal to 0; otherwise, T i is equal to T.
where n is days of the cotton growing period. Suppose T is average daily temperature; when T is equal or less than 15, T i is equal to 0; otherwise, T i is equal to T. Duration in days of temperature equal to or greater than 15 centigrade (DD_15) This calculation was divided into two steps: the calculation of the start time and the calculation of the end time.
Start time. Taking the cotton growing period as an example, first, the date (i) when the average daily temperature first exceeded or was equal to 15 • C had to be identified. Second, the five-day moving average temperature (T i−4 , i ≥ 5) was calculated by pushing forward four days (Formula (3)). Then, the first five-day moving average temperature of 15 • C or above was selected from the longest five-day moving average temperature sequence of 15 • C or more in the growing period. Thirdly, from the five days that make up the five-day moving average temperature (T 15 ), the first day (D start ) when the daily average temperature exceeded or was equal to 15 • C was selected, and D start was the starting time of the stable period passing through 15 • C.
End time. During the cotton growing period, the date (j) when the daily average temperature first appeared to be less than 15 • C was identified from the daily average temperature. Then, the five-day moving average temperature (T j−4 , j ≥ 5) was calculated by pushing forward four days (Formula (4)). Following this, the last five-day moving average temperature equal to or greater than 15 • C (T m−4 , m ≥ 6) was selected. Finally, the last day (D end ) with an average daily temperature greater than or equal to 15 • C was selected from the five days constituting T m−4 .

Soil and Water Resource Data
Based on the MODIS vegetation index data of 250 m resolution in 2005, the cultivated land distribution was obtained by human-computer interactive interpretation and analysis [33]. A Chinese soil dataset based on the world soil database (hwsd) (v1.1) was applied to extract soil texture (ST), soil depth (SD), and soil PH (S_PH) values. Drainage density (DD) was obtained based on the river distribution data. The average annual total amount of water resources per unit area (TAW) was calculated based on the runoff yield modulus of the secondary basin from 2010 to 2016. Then, according to the threshold of Agriculture 2021, 11, 759 6 of 23 indexes, ST, SD, S_PH, DD, and TAW were resampled to the raster surface at 30-m spatial resolution and reclassified into suitable and unsuitable areas for the identification of cotton seed production bases.

Production Risk
The frequency of meteorological disasters (FMD) was calculated based on meteorological disasters from 2000 to 2011. The frequency of pest diseases (FPD) was calculated based on pest risk from 2000 to 2011. The mean Kendall method [34] was applied to calculate the precipitation change rate (PCR) by using precipitation from 1950 to 2018. The average cotton yield reduction rate [35] over the years (AYR) was calculated from the cotton yield. FMD, FPD, and PCR were interpolated into raster surfaces at a 30-m spatial resolution based on the IDW method, and AYR was converted into raster surfaces at a 30-m spatial resolution. FMD and FPD were both divided into two classes of high and low by using the natural breaks (Jenks) method, with low indicating better identification of cotton seed production bases. In addition, PCR and AYR were reclassified into large and small, where small meant good cotton seed production base identification.

Socioeconomic Data
County-level cotton yield from 2015 to 2017 was used to calculate the annual cotton yield (ACY). Road density (RD) was calculated based on distribution data using linear density analysis. The density of cotton seed production enterprises (DCE) and the accessibility of farmland to seed production enterprises (AFE) were calculated from the distribution of cotton seed production enterprises by using point density and Euclidean distance methods in ArcGIS. There were two steps to obtain the data of cotton seed production enterprises. Firstly, based on the Baidu map, the seed companies in the research area were obtained by using "seed industry company" as the search keyword. Secondly, the cotton seed production companies were screened out. Then, the longitude and latitude coordinates of cotton seed production companies were obtained based on the Baidu map picking coordinate system, and the distribution points of seed production companies were obtained by importing them into the geographic database. ACY, RD, DCE, and AFE from the above were required to be converted into a raster surface at 30-m spatial resolution. The natural breaks (Jenks) method was applied to reclassify ACY, RD, and AFE into high-low, high-low, and easy-difficult, respectively, where high and easy indicated superior selection of cotton seed production bases. DCE was divided into greater than 0 and equal to 0, where greater than 0 represented a suitable cotton seed production base.

Production History
Currently, there are cotton seed production bases in the Aksu region, Bayingol Mongolian Autonomous Prefecture, Bortala Mongolian Autonomous Prefecture, the Kashi region, and the Tacheng region. We believe that as long as the construction of seed production bases (SDB) is carried out, they will be suitable areas for planting in terms of production history.

Methodology
Based on the hierarchical classification, the identification of three kinds of cotton seed production bases was mainly divided into the following steps ( Figure 2): Step 1: according to the climatic suitability indexes of cotton seed production, the climate suitability of Xinjiang was calculated, and then, the whole region was divided into a suitable climate area and an unsuitable climate area.
Step 2: based on suitability indexes of water and soil conditions for cotton seed production, the suitable climate area obtained in step 1 was divided into a suitable water and soil (W&S) and an unsuitable W&S area.
Step 3: on the basis of suitability indexes of production risk (PR), the suitable W&S area was divided into a low-risk production area and a high-risk production area.
Step 4: on account of the social-economic (SE) suitability indexes of cotton seed production, the SE suitability of seed production was calculated in the low-risk production area obtained in Step 3, and the lowrisk production area was subdivided into a suitable SE and an unsuitable SE area.
Step 5: the suitable SE area was divided into a superior production area and a suitable production area based on the historical situation of cotton seed production.
Step 6: the unsuitable climate area, unsuitable W&S area, and high-risk production area, which were generated in Steps 1, 2, and 3, were grouped into the unsuitable production area. The unsuitable SE area was categorized as the sub-suitable production area.
Step 7: the superior production area, suitable production area, sub-suitable production area, and unsuitable production area were overlaid with cultivated land to obtain the spatial division of cotton seed production in Xinjiang. Finally, considering the fact that the seed production base needs to have a certain scale, the results obtained in Step 7 were screened according to the standard of more than 100 mu (about 6.66 hectare), and, finally, the suitability distribution of the cotton seed production base in the study area was obtained.
Agriculture 2021, 11, x FOR PEER REVIEW 8 of 22 in Steps 1, 2, and 3, were grouped into the unsuitable production area. The unsuitable SE area was categorized as the sub-suitable production area.
Step 7: the superior production area, suitable production area, sub-suitable production area, and unsuitable production area were overlaid with cultivated land to obtain the spatial division of cotton seed production in Xinjiang. Finally, considering the fact that the seed production base needs to have a certain scale, the results obtained in Step 7 were screened according to the standard of more than 100 mu (about 6.66 hectare), and, finally, the suitability distribution of the cotton seed production base in the study area was obtained. As a region may be suitable for different varieties of cotton seed production, in this study, we integrated the above results of different varieties of cotton seed production into the suitability zones to determine the comprehensive cotton seed production suitability in the study area; the method is shown in Figure 3. The suitability judgment of comprehensive seed production in Region_ x was taken as an example. As shown in Figure 3a, Re-gion_ x may be suitable for three cotton varieties for seed production here, and each cotton variety may have three different degrees of suitability for seed production; thus, there will be 27 possibilities (Figure 3b) in the study area, which can be observed in Figure 3a. In each possibility, when, and only when, example 1 appears once, the cotton variety   As a region may be suitable for different varieties of cotton seed production, in this study, we integrated the above results of different varieties of cotton seed production into the suitability zones to determine the comprehensive cotton seed production suitability in the study area; the method is shown in Figure 3. The suitability judgment of comprehensive seed production in Region_ x was taken as an example. As shown in Figure 3a, Region_ x may be suitable for three cotton varieties for seed production here, and each cotton variety may have three different degrees of suitability for seed production; thus, there will be 27 possibilities (Figure 3b) in the study area, which can be observed in Figure 3a. In each possibility, when, and only when, example 1 appears once, the cotton variety represented by example 1 is selected for the seed production scheme of the group; when, and only when, example 1 appears twice, the two cotton varieties represented by example 1 are selected in the seed production scheme of the group; and when example 1 appears three times, it means that any one of the three cotton varieties can be selected for cotton seed production. On the basis of the above judgment, if example 2 appears in a certain possibility, the cotton varieties represented by example 2 are selected for seed production; if example 2 appears twice, the two cotton varieties represented by example 2 are selected for seed production; if there are three instances of example 2, any one of the three cotton varieties can be selected for seed production. Finally, if example 3 appears three times in the combination, it means that any one of the three cotton varieties represented by example 3 can be selected for seed production. three times, it means that any one of the three cotton varieties can be selected for cotton seed production. On the basis of the above judgment, if example 2 appears in a certain possibility, the cotton varieties represented by example 2 are selected for seed production; if example 2 appears twice, the two cotton varieties represented by example 2 are selected for seed production; if there are three instances of example 2, any one of the three cotton varieties can be selected for seed production. Finally, if example 3 appears three times in the combination, it means that any one of the three cotton varieties represented by example 3 can be selected for seed production.
For example, in the possibility of 1a2b2c, Region_x is suitable for three kinds of cotton seed production. However, Region_x is superior for early-maturing cotton seed production and suitable for early-medium-maturing cotton and long staple cotton seed production. Hence, considering the most suitable factor, the seed production scheme selected here is early-maturing cotton seed production. Figure 3. Solutions to the dilemma of the area for different kinds of cotton seed production at the same time, (a) Region_ x may be suitable for three cotton varieties for seed production here, and each cotton variety may have three different degrees of suitability for seed production and (b) 27 possibilities can be observed. (note, 1: superior, 2: suitable, 3: subsuitable, a: early-maturing cotton, b: early-medium-maturing cotton, c: long staple cotton, and 1a: superior cotton seed production area for early-maturing cotton).

Suitable Climate Area for Cotton Seed Production
Among the influencing factors of climate suitability for early-maturing cotton (EMC) seed production, the suitable AAE_10 areas were distributed in southern, northern, and eastern Xinjiang, and among them, the suitable areas were larger in southern Xinjiang. Except for Yili Kazak Autonomous Prefecture, the suitable areas for AT_JA were widely distributed in Xinjiang. The suitable areas for FFP were mainly distributed in Aksu Prefecture, Hotan Prefecture, Kashgar Prefecture, Bayingol Mongolian Autonomous Prefecture, and Tulufan. The suitable areas for DD_35 were mainly distributed in northern Xinjiang, Hotan Prefecture, Aksu Prefecture, and Kashgar Prefecture in southern Xinjiang. In addition, the suitable areas of SR_AO were widely distributed in eastern Xinjiang. The suitable area for ASH was distributed in all regions of Xinjiang, except Bortala Mongol Autonomous Prefecture. The suitable Pre_SO area was mainly distributed in eastern and southern Xinjiang and less so in northern Xinjiang (Figure 4).
Among the factors affecting climate suitability for early-medium-maturing cotton (EMMC) seed production, the suitable AAE_10 areas for EMMC are also distributed in Figure 3. Solutions to the dilemma of the area for different kinds of cotton seed production at the same time, (a) Region_ x may be suitable for three cotton varieties for seed production here, and each cotton variety may have three different degrees of suitability for seed production and (b) 27 possibilities can be observed. (note, 1: superior, 2: suitable, 3: sub-suitable, a: early-maturing cotton, b: early-medium-maturing cotton, c: long staple cotton, and 1a: superior cotton seed production area for early-maturing cotton).
For example, in the possibility of 1a2b2c, Region_x is suitable for three kinds of cotton seed production. However, Region_x is superior for early-maturing cotton seed production and suitable for early-medium-maturing cotton and long staple cotton seed production. Hence, considering the most suitable factor, the seed production scheme selected here is early-maturing cotton seed production.

Suitable Climate Area for Cotton Seed Production
Among the influencing factors of climate suitability for early-maturing cotton (EMC) seed production, the suitable AAE_10 areas were distributed in southern, northern, and eastern Xinjiang, and among them, the suitable areas were larger in southern Xinjiang. Except for Yili Kazak Autonomous Prefecture, the suitable areas for AT_JA were widely distributed in Xinjiang. The suitable areas for FFP were mainly distributed in Aksu Prefecture, Hotan Prefecture, Kashgar Prefecture, Bayingol Mongolian Autonomous Prefecture, and Tulufan. The suitable areas for DD_35 were mainly distributed in northern Xinjiang, Hotan Prefecture, Aksu Prefecture, and Kashgar Prefecture in southern Xinjiang. In addition, the suitable areas of SR_AO were widely distributed in eastern Xinjiang. The suitable area for ASH was distributed in all regions of Xinjiang, except Bortala Mongol Autonomous Prefecture. The suitable Pre_SO area was mainly distributed in eastern and southern Xinjiang and less so in northern Xinjiang (Figure 4).
for early-maturing cotton (EMC) seed production is 2.94 × 10 7 ha, and it is distributed in North and South Xinjiang. The suitable climate area of Aksu Prefecture, Kashgar Prefecture, and Hotan Prefecture in the Tarim Basin of South Xinjiang is widely distributed. The areas suitable for early-medium-maturing cotton (EMMC) and long staple cotton (LSC) seed production are 2.20 × 10 7 and 2.21 × 10 7 ha, respectively. Both the suitable climate areas for EMMC and LSC are mainly distributed in the eastern part of the Tarim Basin (Figures 4-6). . Suitable climate area for early-maturing cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 °C; AT_JA, the average temperature in July and August; FFP, the frost-free period; DD_35, the duration in days of temperature equal to or greater than 35℃; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October. . Suitable climate area for early-maturing cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 • C; AT_JA, the average temperature in July and August; FFP, the frost-free period; DD_35, the duration in days of temperature equal to or greater than 35 • C; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October.
Among the factors affecting climate suitability for early-medium-maturing cotton (EMMC) seed production, the suitable AAE_10 areas for EMMC are also distributed in southern, northern, and eastern Xinjiang, and among them, the suitable areas are larger in southern Xinjiang. The suitable FFP areas for EMMC are mainly distributed in Aksu Prefecture, Kashgar Prefecture, and Hotan Prefecture of southern Xinjiang, eastern Bayingol Mongolian Autonomous Prefecture, and Turpan of eastern Xinjiang. The suitable AAE_15 areas are mainly distributed in southern Xinjiang, while there is minimal distribution in eastern and northern Xinjiang. The suitable DD_15 areas are mainly distributed in southern Xinjiang and the Turpan area of eastern Xinjiang, while the distribution in other areas is relatively small ( Figure 5).
Prefecture, Kashgar Prefecture, and Hotan Prefecture of southern Xinjiang, eastern Bayingol Mongolian Autonomous Prefecture, and Turpan of eastern Xinjiang. The suitable AAE_15 areas are mainly distributed in southern Xinjiang, while there is minimal distribution in eastern and northern Xinjiang. The suitable DD_15 areas are mainly distributed in southern Xinjiang and the Turpan area of eastern Xinjiang, while the distribution in other areas is relatively small ( Figure 5).
The suitable AAE_10 areas for long staple cotton (LSC) are mainly distributed in southern Xinjiang, less so in eastern Xinjiang than in southern Xinjiang, and sporadically in northern Xinjiang. The distribution of other climatic factors, such as AT_JA, DD_35, SR_AO, ASH, and Pre_SO for EMMC and LSC, is the same as that for EMC ( Figure 6).
Under the restriction of the suitable area of the above factors, the suitable climate area for early-maturing cotton (EMC) seed production is 2.94 × 10 7 ha, and it is distributed in North and South Xinjiang. The suitable climate area of Aksu Prefecture, Kashgar Prefecture, and Hotan Prefecture in the Tarim Basin of South Xinjiang is widely distributed. The areas suitable for early-medium-maturing cotton (EMMC) and long staple cotton (LSC) seed production are 2.20 × 10 7 and 2.21 × 10 7 ha, respectively. Both the suitable climate areas for EMMC and LSC are mainly distributed in the eastern part of the Tarim Basin (Figures 4-6). . Suitable climate area for early-maturing cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 °C; AT_JA, the average temperature in July and August; FFP, the frost-free period; DD_35, the duration in days of temperature equal to or greater than 35℃; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October. Figure 5. Suitable climate area for early-medium-maturing cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 • C; AT_JA, the average temperature in July and August; FFP, the frost-free period; DD_35, the duration in days of temperature equal to or greater than 35 • C; AAE_15, the active accumulated temperature greater than 15 • C; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October; DD_15, the duration in days of temperature equal to or greater than 15 • C.
The suitable AAE_10 areas for long staple cotton (LSC) are mainly distributed in southern Xinjiang, less so in eastern Xinjiang than in southern Xinjiang, and sporadically in northern Xinjiang. The distribution of other climatic factors, such as AT_JA, DD_35, SR_AO, ASH, and Pre_SO for EMMC and LSC, is the same as that for EMC ( Figure 6). Figure 5. Suitable climate area for early-medium-maturing cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 °C; AT_JA, the average temperature in July and August; FFP, the frost-free period; DD_35, the duration in days of temperature equal to or greater than 35℃; AAE_15, the active accumulated temperature greater than 15 °C; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October; DD_15, the duration in days of temperature equal to or greater than 15 °C. Figure 6. Suitable climate area for long staple cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 °C; AT_JA, the average temperature in July and August; DD_35, the duration in days of temperature equal to or greater than 35℃; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October.

Suitable Soil and Water Area for Cotton Seed Production
Considering the limitation of topography on cotton seed production, the area with slopes of less than 5 degrees was selected as the suitable slope area for cotton seed production in this study. It can be seen from the figure that except for the Altai Mountains, Tianshan Mountains, Kunlun Mountains, and other high mountain areas, the other areas were suitable slope areas for cotton seed production. The suitable planting soil for cotton is sandy loam; therefore, the suitable ST areas for cotton seed production were mainly distributed in northern Xinjiang. The soil depth and soil PH for the cotton seed production area need to be greater than 30 cm and greater than 6.5 and less than 8, respectively. It can be seen from the figure that only a small part of the study area was unsuitable for SD and S_PH. Except for the southwest of the Altay region, the south of the Turpan and Hami region, and the middle of the Turpan Basin, the suitable areas of river density were widely distributed. The suitable TAW areas were spread over the whole region.
The suitable soil and water areas for EMC, EMMC, and LSC were obtained by binding ST, SD, S_PH, DD, and TAW together. The suitable soil and water areas for EMC, EMMC, and LSC were the same, with 1.46 × 10 7 ha, and were widely distributed in northern Xinjiang (Figure 7). Figure 6. Suitable climate area for long staple cotton seed production, AAE_10, the active accumulated temperature equal to or greater than 10 • C; AT_JA, the average temperature in July and August; DD_35, the duration in days of temperature equal to or greater than 35 • C; SR_AO, the sunshine rate from April to October; ASH, annual sunshine hours; Pre_SO, precipitation from September to October.
Under the restriction of the suitable area of the above factors, the suitable climate area for early-maturing cotton (EMC) seed production is 2.94 × 10 7 ha, and it is distributed in North and South Xinjiang. The suitable climate area of Aksu Prefecture, Kashgar Prefecture, and Hotan Prefecture in the Tarim Basin of South Xinjiang is widely distributed. The areas suitable for early-medium-maturing cotton (EMMC) and long staple cotton (LSC) seed production are 2.20 × 10 7 and 2.21 × 10 7 ha, respectively. Both the suitable climate areas for EMMC and LSC are mainly distributed in the eastern part of the Tarim Basin (Figures 4-6).

Suitable Soil and Water Area for Cotton Seed Production
Considering the limitation of topography on cotton seed production, the area with slopes of less than 5 degrees was selected as the suitable slope area for cotton seed production in this study. It can be seen from the figure that except for the Altai Mountains, Tianshan Mountains, Kunlun Mountains, and other high mountain areas, the other areas were suitable slope areas for cotton seed production. The suitable planting soil for cotton is sandy loam; therefore, the suitable ST areas for cotton seed production were mainly distributed in northern Xinjiang. The soil depth and soil PH for the cotton seed production area need to be greater than 30 cm and greater than 6.5 and less than 8, respectively. It can be seen from the figure that only a small part of the study area was unsuitable for SD and S_PH. Except for the southwest of the Altay region, the south of the Turpan and Hami region, and the middle of the Turpan Basin, the suitable areas of river density were widely distributed. The suitable TAW areas were spread over the whole region.
The suitable soil and water areas for EMC, EMMC, and LSC were obtained by binding ST, SD, S_PH, DD, and TAW together. The suitable soil and water areas for EMC, EMMC, and LSC were the same, with 1.46 × 10 7 ha, and were widely distributed in northern Xinjiang (Figure 7).

Low-Risk Production Area for Cotton Seed Production
Except for the southwest of Bayingol Mongolian Autonomous Prefecture and the southeast of Tarbagatay Prefecture, the whole region was an FMD low-risk area. Except for the southwest of Bayingolin Autonomous Prefecture, eastern Hotan Prefecture, and a small part of Kashgar Prefecture, the whole region was an FPD low-risk area. The PCR low-risk area was mainly distributed in northern and southern Xinjiang and less so in eastern Xinjiang. Excluding the northern Altay Prefecture, northern Tarbagatay Prefecture, Ili Kazakh Autonomous Prefecture, Changji Hui Autonomous Prefecture, and northern Hami, the remainder were AYR low-risk areas.
To sum up, the low-risk production areas for EMC, EMMC, and LSC were also the same. The low-risk area for cotton seed production was 6.08 × 10 7 ha, which was mainly distributed in the western region of the Junggar basin in the north and the western region of the Tarim Basin in the south (Figure 8).

Low-Risk Production Area for Cotton Seed Production
Except for the southwest of Bayingol Mongolian Autonomous Prefecture and the southeast of Tarbagatay Prefecture, the whole region was an FMD low-risk area. Except for the southwest of Bayingolin Autonomous Prefecture, eastern Hotan Prefecture, and a small part of Kashgar Prefecture, the whole region was an FPD low-risk area. The PCR low-risk area was mainly distributed in northern and southern Xinjiang and less so in eastern Xinjiang. Excluding the northern Altay Prefecture, northern Tarbagatay Prefecture, Ili Kazakh Autonomous Prefecture, Changji Hui Autonomous Prefecture, and northern Hami, the remainder were AYR low-risk areas.
To sum up, the low-risk production areas for EMC, EMMC, and LSC were also the same. The low-risk area for cotton seed production was 6.08 × 10 7 ha, which was mainly distributed in the western region of the Junggar basin in the north and the western region of the Tarim Basin in the south (Figure 8).

Low-Risk Production Area for Cotton Seed Production
Except for the southwest of Bayingol Mongolian Autonomous Prefecture and the southeast of Tarbagatay Prefecture, the whole region was an FMD low-risk area. Except for the southwest of Bayingolin Autonomous Prefecture, eastern Hotan Prefecture, and a small part of Kashgar Prefecture, the whole region was an FPD low-risk area. The PCR low-risk area was mainly distributed in northern and southern Xinjiang and less so in eastern Xinjiang. Excluding the northern Altay Prefecture, northern Tarbagatay Prefecture, Ili Kazakh Autonomous Prefecture, Changji Hui Autonomous Prefecture, and northern Hami, the remainder were AYR low-risk areas.
To sum up, the low-risk production areas for EMC, EMMC, and LSC were also the same. The low-risk area for cotton seed production was 6.08 × 10 7 ha, which was mainly distributed in the western region of the Junggar basin in the north and the western region of the Tarim Basin in the south (Figure 8). Figure 8. Suitable production risk area for cotton seed production, FMD, the frequency of meteorological disasters; FPD, the frequency of pest diseases; PCR, the precipitation change rate; AYR, the average cotton yield reduction rate over the years.

Suitable Social-Economic Area for Cotton Seed Production
The suitable social-economic area for EMC, EMMC, and LSC were also the same. Areas with high ACY were spread over the study region, except for the Altay Prefecture, southern Ili Kazak Autonomous Prefecture, Urumqi, and eastern Changji Hui Autonomous Prefecture. Except for the middle part of the Tarim Basin, the road network density in other areas was relatively high. In terms of AFE, the suitable areas for cotton seed production were mainly located in the northern and southwestern Xinjiang. With regard to DCE, the areas suitable for cotton seed production were mainly distributed in the central and western parts of Xinjiang, with a circular distribution around seed production enterprises.
Under the restriction of the above social and economic factors, the suitable social and economic zone for cotton seed production was 1.23 × 10 7 ha and was mainly located in the north of Bayingol Mongolian Autonomous Prefecture, the middle and north of Aksu Prefecture, the middle of Kashgar Prefecture, the west of Turpan, the middle of Changji Hui Autonomous Prefecture and Karamay, the west of Bortala Mongol Autonomous Prefecture and Ili Kazak Autonomous Prefecture, and the north of Tarbagatay Prefecture (Figure 9). Figure 8. Suitable production risk area for cotton seed production, FMD, the frequency of meteorological disasters; FPD, the frequency of pest diseases; PCR, the precipitation change rate; AYR, the average cotton yield reduction rate over the years.

Suitable Social-Economic Area for Cotton Seed Production
The suitable social-economic area for EMC, EMMC, and LSC were also the same. Areas with high ACY were spread over the study region, except for the Altay Prefecture, southern Ili Kazak Autonomous Prefecture, Urumqi, and eastern Changji Hui Autonomous Prefecture. Except for the middle part of the Tarim Basin, the road network density in other areas was relatively high. In terms of AFE, the suitable areas for cotton seed production were mainly located in the northern and southwestern Xinjiang. With regard to DCE, the areas suitable for cotton seed production were mainly distributed in the central and western parts of Xinjiang, with a circular distribution around seed production enterprises.
Under the restriction of the above social and economic factors, the suitable social and economic zone for cotton seed production was 1.23 × 10 7 ha and was mainly located in the north of Bayingol Mongolian Autonomous Prefecture, the middle and north of Aksu Prefecture, the middle of Kashgar Prefecture, the west of Turpan, the middle of Changji Hui Autonomous Prefecture and Karamay, the west of Bortala Mongol Autonomous Prefecture and Ili Kazak Autonomous Prefecture, and the north of Tarbagatay Prefecture ( Figure  9). . Suitable social and economic area for cotton seed production, ACY, the annual cotton yield; RD, road density; AFE, the accessibility of farmland to seed production enterprises; DCE, the density of cotton seed production enterprises.

Cotton Production History
There has been cotton seed production in the north of the Kashgar Prefecture, Aksu Prefecture, Tarbagatay Prefecture, and Bortala Mongol Autonomous Prefecture; thus, these areas are suitable for seed production from the perspective of historical suitability ( Figure 10). Figure 9. Suitable social and economic area for cotton seed production, ACY, the annual cotton yield; RD, road density; AFE, the accessibility of farmland to seed production enterprises; DCE, the density of cotton seed production enterprises.

Cotton Production History
There has been cotton seed production in the north of the Kashgar Prefecture, Aksu Prefecture, Tarbagatay Prefecture, and Bortala Mongol Autonomous Prefecture; thus, these areas are suitable for seed production from the perspective of historical suitability ( Figure 10).
Agriculture 2021, 11, x FOR PEER REVIEW 1 Figure 10. Suitable area for cotton seed production with regard to production history.

Early-Maturing Cotton (EMC) Seed Production Suitability
Based on the hierarchical classification, we integrated the climate suitability, s water suitability, social-economic suitability, production risk, and planting history velop the spatial distribution of EMC seed production suitability. The appropria for seed production of EMC was 6.4 × 10 5 ha, and it was mainly distributed in the K Prefecture, Hotan Prefecture, and Aksu Prefecture of southern Xinjiang. Among t propriate areas, the superior area was 2.3 × 10 5 ha, which was mainly distributed middle of the Aksu Prefecture and the north of the Kashgar Prefecture. Aksu City awat County, Makit County, Shule County, and Wensu County were the top five su areas for EMC seed production. The suitable area was 9.7 × 10 4 ha, which was m distributed in the northwest of Kashgar Prefecture. Atushi City, Yopurga C Qeshqer Shehiri, Aketao County, and Shufu County were the top five suitable ar EMC seed production. The sub-suitable area was 3.1 × 10 5 ha, which was mainly d uted in the north of the Kashgar Prefecture and the middle of the Aksu Prefecture. City, Marabishi County, Kuqa County, Shaya County, and Yengisar County were t five sub-suitable areas for EMC seed production (Figures 11a and 12).

Early-Medium-Maturing Cotton (EMMC) Seed Production Suitability
The appropriate area for seed production of EMMC was 5.5 × 10 5 ha, and mainly distributed in the north of the Kashgar Prefecture, the middle of the Aksu ture, and the Hotan Prefecture. Among the appropriate areas, the superior area wa 10 5 ha, which was distributed in the north of the Kashgar Prefecture and the middle Aksu Prefecture. Aksu City, Payzawat County, Makit County, Shule County, and W County were the top five superior areas for EMMC seed production. The suitab was 6.8 × 10 4 ha, which was distributed in the northwest of the Kashgar Prefecture awat County, Yopurga County, Qeshqer Shehiri, Aketao County, and Shufu Count the top five suitable areas for EMMC seed production. The sub-suitable area was 2 Figure 10. Suitable area for cotton seed production with regard to production history.

Early-Maturing Cotton (EMC) Seed Production Suitability
Based on the hierarchical classification, we integrated the climate suitability, soil and water suitability, social-economic suitability, production risk, and planting history to develop the spatial distribution of EMC seed production suitability. The appropriate area for seed production of EMC was 6.4 × 10 5 ha, and it was mainly distributed in the Kashgar Prefecture, Hotan Prefecture, and Aksu Prefecture of southern Xinjiang. Among the appropriate areas, the superior area was 2.3 × 10 5 ha, which was mainly distributed in the middle of the Aksu Prefecture and the north of the Kashgar Prefecture. Aksu City, Payzawat County, Makit County, Shule County, and Wensu County were the top five superior areas for EMC seed production. The suitable area was 9.7 × 10 4 ha, which was mainly distributed in the northwest of Kashgar Prefecture. Atushi City, Yopurga County, Qeshqer Shehiri, Aketao County, and Shufu County were the top five suitable areas for EMC seed production. The sub-suitable area was 3.1 × 10 5 ha, which was mainly distributed in the north of the Kashgar Prefecture and the middle of the Aksu Prefecture. Akesu City, Marabishi County, Kuqa County, Shaya County, and Yengisar County were the top five sub-suitable areas for EMC seed production (Figures 11a and 12).

Comparison of the Results
According to the average planting area of cotton in Xinjiang from 2008 to 2018, the whole region of Xinjiang can be divided into north Xinjiang cotton-free area, north Xin-

Early-Medium-Maturing Cotton (EMMC) Seed Production Suitability
The appropriate area for seed production of EMMC was 5.5 × 10 5 ha, and it was mainly distributed in the north of the Kashgar Prefecture, the middle of the Aksu Prefecture, and the Hotan Prefecture. Among the appropriate areas, the superior area was 2.2 × 10 5 ha, which was distributed in the north of the Kashgar Prefecture and the middle of the Aksu Prefecture. Aksu City, Payzawat County, Makit County, Shule County, and Wensu County were the top five superior areas for EMMC seed production. The suitable area was 6.8 × 10 4 ha, which was distributed in the northwest of the Kashgar Prefecture. Payzawat County, Yopurga County, Qeshqer Shehiri, Aketao County, and Shufu County were the top five suitable areas for EMMC seed production. The sub-suitable area was 2.7 × 10 5 ha and was distributed in the north of the Kashgar Prefecture, the middle and west of the Hotan Prefecture, and the middle of the Aksu Prefecture. Akesu City, Marabishi County, Kuqa County, Shaya County, and Yengisar County were the top five sub-suitable areas for EMMC seed production (Figures 11b and 12).

Long Staple Cotton (LSC) Seed Production Suitability
The appropriate area for seed production of LSC was 3.6 × 10 5 ha and was distributed in the north of the Kashgar Prefecture, the middle and west of the Hotan Prefecture, and the east of the Aksu Prefecture. Among the appropriate areas, the superior was 1.1 × 10 5 ha, which is distributed in the northern part of the Kashgar Prefecture and the central and southern part of the Aksu Prefecture. Aksu City, Payzawat County, Makit County, Shule County, and Yarkant County were the top five superior areas for LSC seed production. The suitable area was 5.3 × 10 4 ha, which was distributed in the northwest of the Kashgar Prefecture. Atush City, Payzawat County, Yopurga County, Qeshqer Shehiri, and Shufu County were the top five suitable areas for LSC seed production. The sub-suitable area was 2.1 × 10 5 ha, which was distributed in the north of the Kashgar prefecture, the east of the Aksu Prefecture, and the mid-west area of the Hotan Prefecture. Marabishi County, Kuqa County, Pishan County, Shaya County, and Yengisar County were the top five sub-suitable area for LSC seed production (Figures 11c and 12).

Comprehensive Suitability for the Three Varieties of Cotton Seed Production Aeras
We integrated the suitability of seed production for three kinds of cotton to obtain the integrated layout of cotton seed production. There are only three types of combinations among the suitability of seed production for EMC, EMMC, and LSC, which are 1a1b1c, with 1.0 × 10 5 ha (superior for EMC, EMMC, or LSC seed production); 2a2b2c, with 5.2 × 10 4 ha (suitable for EMC, EMMC, or LSC seed production); and 3a3b3c, with 2.0 × 10 5 ha (sub-suitable for EMC, EMMC, or LSC seed production). The major superior areas for producing cotton seed of EMC, EMMC, and LSC seed production included Shule County, Makit County, Payzawat County, Aksu City, and Yarkant County. The suitable areas for EMC, EMMC, and LSC seed production included Shufu County, Qeshqer Shehiri, and Yopurga County, accounting for nearly 90% of the total suitable areas for EMC, EMMC, and LSC seed production. The sub-suitable areas for EMC, EMMC, and LSC seed production were relatively large, with Shaya County, Marabishi County, Kuqa City, and Yengisar County being the most distributed ( Figure 11d, Table 2).

Comparison of the Results
According to the average planting area of cotton in Xinjiang from 2008 to 2018, the whole region of Xinjiang can be divided into north Xinjiang cotton-free area, north Xinjiang cotton area, east Xinjiang cotton area, north Tarim Basin cotton area, west Tarim Basin cotton area, and east Tarim Basin cotton area (Figure 13a).
The planting areas of long staple cotton (LSC) are mainly in the northwest edge of south Tarim Basin and Wusu city in Northern Xinjiang (Figure 13b). In this study, the candidate areas of LSC seed production included the superior and sub-suitable areas in Aksu Prefecture, which are located in the southern piedmont of Tianshan Mountain, the superior, suitable, and sub-suitable areas in the Kashgar Prefecture of the western margin of Tarim Basin, and the sub-suitable areas in the Hotan Prefecture in the southern margin of Tarim Basin. Compared with the existing planting areas of LSC, the layout of LSC in this study does not exist in north Xinjiang, which is mainly because the active accumulated temperature greater than or equal to 10 • C in north Xinjiang does not meet the requirement of 4000 • C. priorities in future EMC seed production.
The appropriate areas for early-medium-maturing cotton (EMMC) seed production in the northwest and southwest of Tarim Basinare were consistent with EMMC planting areas [37] (Figure 13d). However, in the eastern part of Tarim Basin and Hami of eastern Xinjiang, even if there is EMMC cotton planting, it is not suitable for EMMC seed production, mainly because the climate conditions in these two areas are not suitable, and in addition, the social and economic suitability is not good.

The Necessity of Scientific Layout of Cotton Seed Production
Agriculture constitutes an important part of the economic development of the desert oasis in Xinjiang, while the ecological environment of the desert oasis is relatively fragile, and water resources are scarce [38]. How to use the limited agricultural production Early-maturing cotton (EMC) planting areas are distributed in both south and north Xinjiang, and the EMC planting area in North Xinjiang is the largest [37]. The EMC planting area in north Xinjiang is located in the north slope of the Tianshan Mountains, southwest edge of Junggar basin, and south of the Gurbantonggut desert, while the EMC planting area in south Xinjiang is mainly distributed in the west of Tarim Basin [37] (Figure 13c). In this study, the alternative areas for EMC seed production were mainly distributed in the Aksu Prefecture in the southern piedmont of the Tianshan Mountain (Superior and suitable area), the Kashgar Prefecture (Superior and suitable area) and the Kizilsu Kirghiz Autonomous Prefecture (Suitable area) of the western margin of Tarim Basin, the Bayingol Mongolian Autonomous Prefecture (Sub-suitable area) in the eastern section of the southern foot of the Tianshan Mountain, and the sub-suitable areas in the Hotan Prefecture in the southern margin of Tarim Basin. The appropriate area of EMC seed production was consistent with the existing EMC planting area. However, different from the existing planting areas of EMC, the superior areas, suitable areas, and sub-suitable areas obtained from the research results were also distributed in other areas; these areas are potential areas for future cotton seed production, which should be given high priorities in future EMC seed production.
The appropriate areas for early-medium-maturing cotton (EMMC) seed production in the northwest and southwest of Tarim Basinare were consistent with EMMC planting areas [37] (Figure 13d). However, in the eastern part of Tarim Basin and Hami of eastern Xinjiang, even if there is EMMC cotton planting, it is not suitable for EMMC seed production, mainly because the climate conditions in these two areas are not suitable, and in addition, the social and economic suitability is not good. Agriculture constitutes an important part of the economic development of the desert oasis in Xinjiang, while the ecological environment of the desert oasis is relatively fragile, and water resources are scarce [38]. How to use the limited agricultural production resources to obtain the maximum output is a problem to which the local government, enterprises, and farmers pay close attention. Crop seed industry can optimize agricultural planting structure, improve agricultural production efficiency, promote farmers' employment, and increase farmers' income. Xinjiang has a large cotton planting area and a large demand for seeds. The annual seed production of the state-owned seed companies in Xinjiang is 150,000 tons, accounting for about 40% of the total seed consumption in the region, and the total sales of cotton seeds are 20 billion to 30 billion yuan [7]; cotton is still the crop with the greatest potential in the seed market. Compared with cotton production, the conditions for cotton seed production are much more stringent. However, Xinjiang government departments and cotton seed production enterprises are not sure how to scientifically arrange cotton seed production; cotton seed industry optimization layout in Xinjiang is imminent.

Rational Utilization of Agricultural Resources in Xinjiang
Research on the distribution of the cotton seed industry is conducive to more scientific and rational agricultural resources in Xinjiang. The breeding of improved varieties is the key to cotton seed production. Compared with the seed production of other crops, cotton has a wide range of good breeding, a large quantity, and many connections. Therefore, arranging cotton seed bases according to the comprehensive power of each cotton area is an effective way of improving the development of cotton seeds in Xinjiang [39].
Climate is the key factor affecting cotton seed production. Relevant research has shown that in recent years, with the rapid development of cotton planting in southern Xinjiang, the excessive expansion of the planting scale due to the lack of attention given to the suitability of climate conditions or the unreasonable selection of variety maturity has led to a low and unstable cotton yield, a low percentage of flowers before frost, and a declining quality, which has seriously affected the economic benefits of cotton production [20].
Xinjiang has abundant land resources and stable water resources. There are vast piedmont alluvial plains in the Tarim and Junggar Basins and alluvial plains of different sizes along the Tarim River, Yarkant River, Manas River, Kuitun River, and Boertala River, which are rich in land resources. Precipitation in the Xinjiang plain is scarce, but there is a lot of water in the mountainous areas around the basin, with surface water resources of 79.3 billion cubic meters. The runoff is adjusted by alpine ice and snow melt water, and the annual change is gentle, which provides a stable and reliable water source for irrigation and cotton planting [28]. However, with the increase in the cotton production scale, the environmental pressure of cotton production in Xinjiang will increase. The water demand characteristics of cotton are consistent with the water regime and climate characteristics of Xinjiang. Before the scale expansion, the environment supported the development of cotton production. However, with the expansion of the scale, cotton has become a major water user in Xinjiang, and it will be difficult for the limited water resources to support the continuous increase in the cotton planting scale. In addition, the problems of soil fertility decline, salinization, and residual film pollution in cotton fields are increasing [6]. Therefore, in order to realize the development of the cotton seed industry, the sustainable utilization of water and soil resources must be taken into account.
Diseases and pests in the Xinjiang cotton area mainly include cotton bollworm disease and cotton aphid wilt. Therefore, in cotton seed production, priority should be given to disease-resistant varieties and biological control, and comprehensive management should be carried out [36].
During the whole growth cycle, from sowing to harvest, cotton may be damaged by disastrous weather, mainly including drought, high temperatures, strong wind, rain, hail, and freezing, which seriously affect the normal production of cotton, resulting in the reduction of yield and income or even no harvest in serious cases. Therefore, prevention work should be conducted in the prenatal period, the climate resources should be rationally used, the advantages and disadvantages should be avoided, and the yield and quality of cotton should be improved as much as possible. Selecting drought-and high-temperatureresistant cotton varieties and actively promoting advanced drip irrigation and other watersaving irrigation technologies can not only save water, but also promote the growth of cotton [29].
Cotton seed production enterprises guarantee the development of the cotton seed industry. There are more than 800 enterprises involved in cotton seed production and sales in Xinjiang. However, large enterprises account for less than 5%, and large and medium-sized enterprises account for less than 25% [39]. There is still considerable room for improvement in the development of cotton seed production enterprises in Xinjiang so as to realize the strong development of the cotton seed industry.
In addition, FAO has introduced sustainable and innovative technologies and practices, namely, "climate-smart agriculture (CSA)", which refers to any innovative practice and technology that helps to enhance farm productivity and farm income, as well as improving water and nutrient use efficiency and resilience to climatic stresses on a sustainable basis and lowering the emissions of greenhouse gas (GHG) to a minimum level [40]. Hence, cotton seed producers can use inputs in an efficient way by using CSA practices and technologies in cotton growing areas.
According to the layout plan in this study, the development of the cotton seed industry is conducive to the protection of resources and environmen, and the sustainable development of the cotton seed industry in Xinjiang.

Conclusions
Based on multi-source data, we developed a hierarchical classification method to identify the suitability of cotton seed production bases in this study. Following the research outlined in this paper, the conclusions are as follows: (1) The suitable climate areas for early-maturing cotton (EMC), early-medium-maturing cotton (EMMC), and long staple cotton (LSC) seed production are 2.94 × 10 7 ha, 2.20 × 10 7 , and 2.21 × 10 7 ha, respectively. The largest distribution area of EMC was observed in the Aksu Prefecture, Kashgar Prefecture, and Hotan Prefecture in the Tarim Basin of South Xinjiang. Both of the suitable climate areas for EMMC and LSC were mainly distributed in the eastern part of the Tarim Basin. The soil and water suitable areas for EMC, EMMC, and LSC were the same at 1.46 × 10 7 ha, and they were widely distributed in northern Xinjiang. The low-risk area for cotton seed production was 6.08 × 10 7 ha, which was mainly distributed in the western region of the Junggar Basin in the north and the western region of the Tarim Basin in the south. The suitable social and economic zone for cotton seed production was 1.23 × 10 7 ha, which was mainly located in the north of the Bayingol Mongolian Autonomous Prefecture, the middle and north of the Aksu Prefecture, the middle of the Kashgar Prefecture, the west of Turpan, the middle of the Changji Hui Autonomous Prefecture and Karamay, the west of the Bortala Mongol Autonomous Prefecture and the Ili Kazak Autonomous Prefecture, and the north of the Tarbagatay Prefecture.
(3) There were only three combinations among the examined areas that were suitable for seed production for EMC, EMMC, and LSC: (i) superior for EMC, EMMC, or LSC seed production: 1.02 × 10 5 ha; (ii) suitable for EMC, EMMC, or LSC seed production: 5.17 × 10 4 ha; (iii) sub-suitable for EMC, EMMC, or LSC seed production: 1.95 × 10 5 ha. The superior area for the production of cotton seed of EMC, EMMC, or LSC was located in the western Tarim Basin. The sub-suitable area for cotton seed production of EMC, EMMC, or LSC was mostly distributed in the western and northern Tarim Basin.
Due to the different climate, soil, water resources, and management measures in different countries and regions, the varieties of cotton seed production varied. However, in any case, the following conditions should be met during the cotton seed production base selection: first, the abundant light and heat resources, which provide unique ecological conditions for cotton production; secondly, the higher degree of mechanization, which provides the most convenient conditions for cotton production; thirdly, perfect agricultural infrastructure, which provides favorable conditions for the sustainable development of cotton; moreover, abundant water resources, which provide the most fundamental guarantee for the development of cotton agriculture; finally, excellent quality of soil fertility conditions, which provide a guarantee for cotton yield. Therefore, considering the above elements, the model developed in this study could be replicated in other areas in the world. In addition, the model was to delimit the cotton seed production base according to the current situation. If climate or other elements affecting cotton seed production changed, the model was capable of judging the change of planting area to a certain extent as well. Besides, this model could also help the government and banks more accurately determine where they will invest to promote the production of cotton seeds.