Farmer’s Participatory Genetic and Agronomic Approaches for Higher Rice Productivity in Sodicity Stress ^†

Abstract

In salt affected soils, neither physical nor chemical remediation methods are cost-effective for saline/sodic soil reclamation. Salt-affected lands are estimated at about 955 million ha worldwide, afflicting over 6% of the world’s total arable land, of which sodic soils constitute 581 million ha. Regaining the agricultural potential and enhancing the productivity and profitability of rice in sodic soils, it necessitates the development of advanced technologies for the sustainable reclamation of these soils, suitable salt tolerant varieties (STVs) through farmer’s participatory varietal selection (FPVS) approaches and their matching management practices (Mmp).The results from the study showed that combining Mmp with STV resulted in 35% higher yields over traditional variety (TV) with farmer’s management practices and proved cost effective nutrient management approach to maximize the productivity and profitability of rice in sodic soils.

1. Introduction

The presence of salts in the soil is an alarming threat to agricultural productivity and sustainability. According to the FAO Land and Nutrition Management Service [1], over 6% of the world’s land is affected by salinity, which accounts 955 million ha in 100 countries, of which sodic/solonetz soils constitute 581 million ha. Chemical amendments like gypsum (CaSO₄·2H₂O) have been used most extensively for the reclamation of sodic soils [2] but is a costly affair because of its requirement in large quantity (12–16 tha⁻¹) and high market price (USD 60 t⁻¹). Therefore, it is imperative to develop cost effective farmers’ participatory sodic soil reclamation technologies.

Rice is an important crop grown in salt-affected soils, but its yield is much lower because of its high sensitivity to salinity and sodicity at early seedling stage [3], high mortality and poor crop establishment [4]. Increasing and sustaining yields in these soils will require the development of high yielding STVs and their integration with cost effective crop and nutrient management practices in farmers’ participatory mode. In this paper we limit the discussion on developing advanced cost effective reclamation technologies, the development of farmers’ preferred high yielding salt tolerant variety of rice through the farmers’ participatory varietal selection (FPVS) approach and improved agronomic management practices to ensure better crop establishment and higher productivity of STV of rice.

2. Materials and Methods

2.1. Development of Advanced Cost-Effective Reclamation Technologies

Four times replicated field experiments laid out in a split plot design with four gypsum levels (control, 15% GR, 25% GR and 50% GR) and two varieties ‘CSR 13 (STV)’ and ‘Pant 4 (TV)’ were conducted for three years in highly sodic soil (pH 10.5, EC 1.43 dSm⁻¹, ESP 89) at the ICAR-Central Soil Salinity Research Institute (CSSRI), Regional Research Station, Lucknow, Uttar Pradesh, India (26°47′58″ N and 80°46′24″ E). As per treatments, gypsum was incorporated once throughout the study in surface soil (0–15 cm). Thirty day old seedlings of both the varieties were transplanted at 20 × 15 cm row to row and plant to plant spacing. After three years of study, soil samples were collected and analyzed to monitor the improvement in soil properties. All the observation related to crop growth, yield attributing characters and yields were recorded and analyzed statistically using the statistical package MSTAT-C.

2.2. Development of High Yielding Salt Tolerant Variety through Farmer’s Participatory Varietal Selection Approach

A set of 126 geographically and genetically diverse rice genotypes includes local genotypes and advanced salt tolerant genotypes were screened through researchers’ managed on-station and on-farm trials. Based on sodicity tolerance and high yield potential, 18 genotypes were selected for FPVS. After 3 years of FPVS studies, conducted at 17 sodic environments, 6 genotypes were selected and further evaluated, taking into account traits desired by men and women farmers. Preference scores for each genotype were calculated. The genotype ‘CSR89IR-8’ consistently ranked first based on both farmers’ preference ranking and grain yield and later released as variety ‘CSR 43’ (

Table 1. Combined effect of gypsum levels and varieties on grain yield (t/ha⁻¹) of rice.

Gypsum Levels (% G.R.)	1st Year		2nd Year		3rd Year
	CSR 13	Pant 4	CSR 13	Pant 4	CSR 13	Pant 4
0	0.32	0.07	0.55	0.36	0.63	0.42
15	2.73	1.57	3.01	2.77	3.28	2.81
25	4.09	3.48	4.38	3.76	4.52	4.11
50	4.36	4.05	4.79	4.36	4.96	4.75
Sem (±)	0.09		0.03		0.08
CD (p = 0.05)	0.27		0.12		0.28

).

2.3. Development of Management Practices

2.3.1. Optimizing Number of Seedling/Hill⁻¹ and Spacing

Field experiments with three replications consisted of two rates of seedlings/hill⁻¹, T1 (2 seedlings) and T2 (4 seedlings), and three spacing S1: 15 × 15 cm, S2: 15 × 20 cm, S3: 20 × 20 cm was conducted at the experimental farm of ICAR-CSSRI, Regional Research Station, Lucknow, Uttar Pradesh, India, on a sodic soil (pH 9.2, EC 0.61 dSm⁻¹). Thirty-day-old seedlings were transplanted with recommended doses of fertilizer.

2.3.2. Optimizing Nitrogen Requirement

A field experiment with three replicates and six N treatments ((N kgha⁻¹) N1: 0, N2: 100, N3: 125, N4: 150, N5: 175 and N6: 200) was conducted at ICAR-CSSRI, Research farm, Shivri, Lucknow. Thirty-day-old seedlings were transplanted with 4 seedlings/hill⁻¹ spaced at 15 × 20 cm. Full P₂O₅, K₂O and ZnSO₄ (60–40–25 kg N–P₂O₅–K₂O–ZnSO₄·7H₂O ha⁻¹) and half of N were applied as basal, and the remaining N was applied in equal splits at 30 and 60 days after transplanting. All the relevant data were collected and analyzed (ANOVA) using WINDOSTAT.

3. Results and Discussion

3.1. Cost Effective Reclamation Technology

Salt tolerant variety ‘CSR 13’ significantly excelled ‘Pant 4′ in grain yield at gypsum levels from 15 to 50% G.R. However, the magnitude of the combined effect of the reduced dose of gypsum and salt tolerant variety of rice was reflected as 17% increase in grain yield over the tradition variety. It indicated that the gypsum, at 25% G.R. with the sodicity-tolerant variety, could save about 43% of the total initial expenditure for the reclamation of sodic soils over the recommended dose of gypsum (50% G.R.) with non-sodicity tolerant traditional high yielding varieties. These observations indicate the saving of gypsum to the tune of 25% by using salt tolerant variety in sodic soils (Table 1). The application of a reduced dose of gypsum and cultivating salt-tolerant varieties saved 50% of gypsum without any significant yield loss [5].

3.2. Development of Salt Tolerant Variety through FPVS

After intensive evaluation and selection within the 126 genotypes, only 6 genotypes were selected (

Table 2. FPVS process for developing salt tolerant variety. The arrow sign is indicating that out of three outstanding performing genotypes only one is selected to develop as a variety.

Year	Process	Number of Genotypes Planted in Sodic Soil	Number of Genotypes Selected	Number of Trials Sites in Sodic Soil
1st	Screening of Genotypes	126	18	2
2nd	To conduct PVS	18	12	5
3rd	To conduct PVS	12	9	6
4th	To conduct PVS	9	6	6
5th	Final selection	6	2	6
6th	Up-scaling	2 + 1 (farmer variety)	1 selected and released as variety “CSR43”	32

). Farmers ranked CSR-89IR-8, CSR36 and NDR359 as their first, second and third preferred genotypes, respectively, with positive correlations between preference scores of male and female farmers (r = 0.91**) and between farmers and researchers (r = 0.74*). Genotype ‘CSR-89IR-8′ ranked first in all desired traits. Farmers selected CSR-89IR-8 as their preferred genotype because of several traits, including its good taste, aroma, color, non-cohesiveness when cooked and higher grain yield. The FPVS program conducted in sodic soils [6] has confirmed the relevance and utility of participatory approaches in these less favorable environments. The screening of a large number of genotypes helped to narrow the number of genotypes suitable for sodic soils. Farmers’ preferences revealed that they generally preferred high yielding, salt tolerant, short duration and lodging-resistant varieties of rice. Based on farmers’ rankings, genotype ‘CSR-89IR-8′ fulfils all the preferred traits. These attributes together culminated in the release of this genotype as CSR 43 [6].

3.3. Improved Management Practices

3.3.1. Optimizing Number of Seedlings/Hill⁻¹ and Spacing

Productive tillers/hill⁻¹, grain and straw yields with four seedlings/hill⁻¹ were, respectively, 15.9%, 22.7% and 30.3% higher than those with two seedlings/hill⁻¹. Spacing had a significant (p < 0.05) effect on floret fertility and grain yield. Using 15 × 20 cm spacing resulted in about 4–7% more spikeletspanicle⁻¹ over both 15 × 15 and 20 × 20 cm spacing though these differences were not significant. Using 15 × 20 cm spacing resulted in 11% higher grain yield and 16% higher straw yield over the values obtained with 20 × 20 cm spacing. Grain yield was significantly enhanced by the transplanting of four seedlings/hill⁻¹ at a 15 × 20 cm spacing. Higher number of seedlings/hill⁻¹ resulted in significantly higher dry matter production and more productive tillers/hill⁻¹, whereas medium spacing enhanced floret fertility resulting in higher grain yield over other treatments [7].

3.3.2. Optimizing Nitrogen Requirement for Salt Tolerant Variety

The application of 200 kg Nha⁻¹ produced 70%, 53.8%, 21.5%, 9.7% and 3.5% more productive tillers/hill⁻¹ than the application of 0, 100, 125, 150 and 175 kg Nha⁻¹, respectively. Number of spikeletspanicle⁻¹ and 1000 grain weight increased significantly by increasing N to 200 and 175 kgha⁻¹. Applying 100 kg Nha⁻¹ resulted in 125% increase in grain yield over control. Grain yield was statistically similar when 175, 200 and 150 kg Nha⁻¹ were used but these yields were significantly higher than when 0, 100 and 125 kg of N were applied. A similar pattern was also observed for straw yield. Nitrogen application is necessary to maintain plant growth and enhance grain yield. Similar beneficial effects of N application in similar environments were reported by Singh et al. [7]. The grain yield of STV responded positively to N application up to 169 kgha⁻¹; however, gross margin and BCR were highest with 150 kg Nha⁻¹. This N rate can, therefore, be recommended for STV in sodic soils.

4. Conclusions

The sodic soils treatment with a reduced dose of gypsum (25% G.R.) and growing a salt-tolerant variety of rice can save 25% of gypsum and proved to be highly economical and sustainable technology for increasing rice productivity. The salt-tolerant variety produced about 0.5 tha⁻¹ additional grain yields over farmers’ current varieties across locations. Suggested recommendations include the transplanting of four seedlings/hill⁻¹ at a spacing of 15 × 20 cm and the use of 150–60–40–25 kg N–P₂O₅–K₂O–ZnSO₄·7H₂O ha⁻¹ in the field.