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20 pages, 2421 KiB  
Article
Mitigation of Water-Deficit Stress in Soybean by Seaweed Extract: The Integrated Approaches of UAV-Based Remote Sensing and a Field Trial
by Md. Raihanul Islam, Hasan Muhammad Abdullah, Md Farhadur Rahman, Mahfuzul Islam, Abdul Kaium Tuhin, Md Ashiquzzaman, Kh Shakibul Islam and Daniel Geisseler
Drones 2025, 9(7), 487; https://doi.org/10.3390/drones9070487 - 10 Jul 2025
Viewed by 374
Abstract
In recent years, global agriculture has encountered several challenges exacerbated by the effects of changes in climate, such as extreme water shortages for irrigation and heat waves. Water-deficit stress adversely affects the morpho-physiology of numerous crops, including soybean (Glycine max L.), which [...] Read more.
In recent years, global agriculture has encountered several challenges exacerbated by the effects of changes in climate, such as extreme water shortages for irrigation and heat waves. Water-deficit stress adversely affects the morpho-physiology of numerous crops, including soybean (Glycine max L.), which is considered as promising crop in Bangladesh. Seaweed extract (SWE) has the potential to improve crop yield and alleviate the adverse effects of water-deficit stress. Remote and proximal sensing are also extensively utilized in estimating morpho-physiological traits owing to their cost-efficiency and non-destructive characteristics. The study was carried out to evaluate soybean morpho-physiological traits under the application of water extracts of Gracilaria tenuistipitata var. liui (red seaweed) with two varying irrigation water conditions (100% of total crop water requirement (TCWR) and 70% of TCWR). Principal component analysis (PCA) revealed that among the four treatments, the 70% irrigation + 5% (v/v) SWE and the 100% irrigation treatments overlapped, indicating that the application of SWE effectively mitigated water-deficit stress in soybeans. This result demonstrates that the foliar application of 5% SWE enabled soybeans to achieve morpho-physiological performance comparable to that of fully irrigated plants while reducing irrigation water use by 30%. Based on Pearson’s correlation matrix, a simple linear regression model was used to ascertain the relationship between unmanned aerial vehicle (UAV)-derived vegetation indices and the field-measured physiological characteristics of soybean. The Normalized Difference Red Edge (NDRE) strongly correlated with stomatal conductance (R2 = 0.76), photosystem II efficiency (R2 = 0.78), maximum fluorescence (R2 = 0.64), and apparent transpiration rate (R2 = 0.69). The Soil Adjusted Vegetation Index (SAVI) had the highest correlation with leaf relative water content (R2 = 0.87), the Blue Normalized Difference Vegetation Index (bNDVI) with steady-state fluorescence (R2 = 0.56) and vapor pressure deficit (R2 = 0.74), and the Green Normalized Difference Vegetation Index (gNDVI) with chlorophyll content (R2 = 0.73). Our results demonstrate how UAV and physiological data can be integrated to improve precision soybean farming and support sustainable soybean production under water-deficit stress. Full article
(This article belongs to the Special Issue Recent Advances in Crop Protection Using UAV and UGV)
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15 pages, 1019 KiB  
Article
Genotypic Variability in Growth and Leaf-Level Physiological Performance of Highly Improved Genotypes of Pinus radiata D. Don Across Different Sites in Central Chile
by Sergio Espinoza, Marco Yáñez, Carlos Magni, Eduardo Martínez-Herrera, Karen Peña-Rojas, Sergio Donoso, Marcos Carrasco-Benavides and Samuel Ortega-Farias
Forests 2025, 16(7), 1108; https://doi.org/10.3390/f16071108 - 4 Jul 2025
Viewed by 217
Abstract
Pinus radiata D. Don is planted in South Central Chile on a wide range of sites using genetically improved genotypes for timber production. As drought events are expected to increase with ongoing climatic change, the variability in gas exchange, which could impact growth [...] Read more.
Pinus radiata D. Don is planted in South Central Chile on a wide range of sites using genetically improved genotypes for timber production. As drought events are expected to increase with ongoing climatic change, the variability in gas exchange, which could impact growth and water use, needs to be evaluated. In this study, we assessed the genotypic variability of leaf-level light-saturated photosynthesis (Asat), stomatal conductance (gs), transpiration (E), intrinsic water use efficiency (iWUE), and Chlorophyll a fluorescence (OJIP-test parameters) among 30 P. radiata genotypes (i.e., full-sib families) from third-cycle parents at age 6 years on three sites in Central Chile. We also evaluated tree height (HT), diameter at breast height (DBH), and stem index volume (VOL). Families were ranked for HT as top-15 and bottom-15. In the OJIP-test parameters we observed differences at the family level for the maximum quantum yield of primary PSII photochemistry (Fv/Fm), the probability that a photon trapped by the PSII reaction center enters the electron transport chain (ψEo), and the potential for energy conservation from photons captured by PSII to the reduction in intersystem electron acceptors (PIABS). Fv/Fm, PIABS, and ψEo ranged from 0.82 to 0.87, 45 to 95, and 0.57 to 0.64, respectively. Differences among families for growth and not for leaf-level physiology were detected. DBT, H, and VOL were higher in the top-15 families (12.6 cm, 8.4 m, and 0.10 m3, respectively) whereas Asat, gs, E, and iWUE were similar in both the top-15 and bottom-15 families (4.0 μmol m−2 s−1, 0.023 mol m−2 s−1, 0.36 mmol m−2 s−1, and 185 μmol mol m−2 s−1, respectively). However, no family by site interaction was detected for growth and leaf-level physiology. The results of this study suggest that highly improved genotypes of P. radiata have uniformity in leaf-level physiological rates, which could imply uniform water use at the stand-level. The family variation found in PIABS suggests that this parameter could be incorporated to select genotypes tolerant to environmentally stressful conditions. Full article
(This article belongs to the Special Issue Water Use Efficiency of Forest Trees)
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16 pages, 3716 KiB  
Article
Water Demand and Photosynthetic Performance of Tomatoes Grown Hydroponically Under Increasing Nitrogen Concentrations
by Pablo Rugero Magalhães Dourado, Martha Katharinne Silva Souza Paulino, Lucas Yago de Carvalho Leal, Cicero Aparecido Ferreira Araújo, José Alfredo Nunes, Emidio Cantídio de Oliveira, José Amilton Santos Júnior, Aline de Camargo Santos, Diego Arruda Huggins de Sá Leitão, Márcio Renato Nunes, Bruce Schaffer and Edivan Rodrigues de Souza
Water 2025, 17(13), 1951; https://doi.org/10.3390/w17131951 - 29 Jun 2025
Viewed by 413
Abstract
Water and nitrogen (N) availability are among the primary limiting factors for the productivity of tomato (Solanum licopersicum L.). This study evaluated the interaction between these factors by assessing the effects of different N concentrations (85.5, 128.3, 171.0, 213.8, and 256.1 ppm [...] Read more.
Water and nitrogen (N) availability are among the primary limiting factors for the productivity of tomato (Solanum licopersicum L.). This study evaluated the interaction between these factors by assessing the effects of different N concentrations (85.5, 128.3, 171.0, 213.8, and 256.1 ppm N) on the water consumption, growth, and photosynthetic efficiency of hydroponically-grown tomato plants. The variables that were analyzed included the leaf N content, leaf chlorophyll index (LCI), maximum quantum efficiency of photosystem II (the ratio of variable to maximum chlorophyll fluorescence; Fv/Fm), non-photochemical quenching (NPQ), fresh mass (FM), dry mass (DM), cumulative water consumption, and water use efficiency (WUE). Increasing N concentrations led to higher water consumption and FM accumulation. Dry biomass was quadratically related to the N concentration, which peaked between doses of 213.8 and 256.1 ppm N. The LCI and Fv/Fm increased with the N supply, reaching a peak at N concentrations above 171 ppm, and then remained relatively constant. Conversely, the NPQ was reduced at the highest N level (256.1 ppm), which indicated diminished excess energy dissipation capacity. The highest WUE was observed at 213.8 ppm N, which was associated with greater DM and reduced water consumption compared to the highest N treatment. These findings suggest that the N concentration significantly affects the biomass production and water use in hydroponically-grown tomato plants, with 213.8 ppm N being the most efficient for vegetative growth under the studied conditions. Full article
(This article belongs to the Special Issue Soil Water Use and Irrigation Management)
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23 pages, 2768 KiB  
Article
Evolution of Non-Destructive and Destructive Peach ‘Redhaven’ Quality Traits During Maturation
by Marko Vuković, Dejan Ljubobratović, Maja Matetić, Marija Brkić Bakarić, Slaven Jurić and Tomislav Jemrić
Agronomy 2025, 15(6), 1476; https://doi.org/10.3390/agronomy15061476 - 17 Jun 2025
Viewed by 611
Abstract
The main goal of this study was to investigate and better understand the evolution of the main non-destructive and destructive quality parameters of peach ‘Redhaven’ during ripening process. This study was conducted from 8 to 21 July 2023, during which peaches ‘Redhaven’ were [...] Read more.
The main goal of this study was to investigate and better understand the evolution of the main non-destructive and destructive quality parameters of peach ‘Redhaven’ during ripening process. This study was conducted from 8 to 21 July 2023, during which peaches ‘Redhaven’ were harvested each second day from a commercial orchard located in Novaki Bistranjski. Maturity categories were defined according to different firmness thresholds: maturity for long-distance chain stores (H1), maturity for medium-distance chain stores (H2), maturity below the defined maximum firmness in order to preserve optimal quality traits (H3), ready to buy (H4), ready to eat (H5), and overripe (H6). The chlorophyll absorbance index was the non-destructive parameter that was mostly distinguished between maturity categories (r = 0.78 with firmness), followed by a* and h° ground colour parameters. During the first three maturity categories (H1–H3), firmness had a notably smaller correlation with titratable acidity and the ratio of total soluble solids and titratable acidity, which is not the case for a* and h° ground colour parameters, chlorophyll absorbance index, and the share of additional colour. During the last three maturity categories (H4–H6), non-destructive parameters are not reliable for maturity prediction. When ground colour parameters are measured near petiole insertion, mostly smaller segregation between maturity categories is obtained compared to when measured at the rest of the fruit. Total polyphenol and flavonoid content in peach juice notably corelated only in the last two maturity categories with L* ground colour parameter. Full article
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32 pages, 13709 KiB  
Article
An Innovative Inversion Method of Potato Canopy Chlorophyll Content Based on the AFFS Algorithm and the CDE-EHO-GBM Model
by Xiaofei Yang, Qiao Li, Honghui Li, Hao Zhou, Jinyan Zhang and Xueliang Fu
Agriculture 2025, 15(11), 1181; https://doi.org/10.3390/agriculture15111181 - 29 May 2025
Viewed by 522
Abstract
Chlorophyll content is an important indicator for estimating potato growth. However, there are still some research gaps in the inversion of canopy chlorophyll content using unmanned aerial vehicle (UAV) remote sensing. For example, it faces limitations of the growth cycle, low parameter accuracy, [...] Read more.
Chlorophyll content is an important indicator for estimating potato growth. However, there are still some research gaps in the inversion of canopy chlorophyll content using unmanned aerial vehicle (UAV) remote sensing. For example, it faces limitations of the growth cycle, low parameter accuracy, and single feature selection, and there is a lack of efficient and precise systematic research methods. In this study, an improved Adaptive-Forward Feature Selection (AFFS) algorithm was developed by combining remote sensing data and measured data to optimize the input Vegetation Index (VI) variables. Gradient Boosting Machine (GBM) model parameters were optimized using a hybrid strategy improved Elephant Herd Optimization (EHO) algorithm (CDE-EHO) that combines Differential Evolution (DE) and Cauchy Mutation (CM). The CDE-EHO method optimizes the GBM model, achieving maximum accuracy, according to the testing results. The optimal coefficients of determination (R2) values of the prediction set are 0.663, 0.683, and 0.906, respectively, the Root Mean Squared Error (RMSE) values are 2.673, 3.218, and 2.480, respectively, and the Mean Absolute Error (MAE) values are 2.052, 2.732, and 1.928, respectively, during the seedling stage, tuber expansion stage and cross-growth stage. This approach has significantly enhanced the inversion model’s prediction performance as compared to earlier research. The chlorophyll content in the potato canopy has been accurately extracted in this work, offering fresh perspectives and sources for further research in this area. Full article
(This article belongs to the Section Artificial Intelligence and Digital Agriculture)
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17 pages, 3139 KiB  
Article
Effects of Ammonium on Assimilate Translocation and Storage Root Growth in Sushu16 in Root-Swelling Stage
by Wenjing Yao, Rui Zhou, Qin Tan, Chun Zhuang, Wenqi Shao, Chuan Chen and Chuanzhe Li
Agronomy 2025, 15(6), 1272; https://doi.org/10.3390/agronomy15061272 - 22 May 2025
Viewed by 350
Abstract
Ammonium greatly influences nutrient partitioning and root architecture, particularly in the tuberous crops where assimilate translocation is critical for yield formation. However, relatively few studies have systematically delved into the physiological and molecular mechanisms of ammonium on assimilate translocation and root growth in [...] Read more.
Ammonium greatly influences nutrient partitioning and root architecture, particularly in the tuberous crops where assimilate translocation is critical for yield formation. However, relatively few studies have systematically delved into the physiological and molecular mechanisms of ammonium on assimilate translocation and root growth in sweetpotato (Ipomoea batatas Lam.). In this study, we investigated the morphological, physiological, and molecular effects of different concentrations of ammonium (0, 0.5, 1.0, 3.0, 5.0 mM) on the growth of the Sushu16 variety in the root-swelling stage. The plant weight and leaf area index of Sushu16 seedlings exhibited a progressive increase with elevated ammonium levels. However, the weight, volume, and number of storage roots (SRs) displayed a trend of a rapid rise and substantial decline, peaking at 1 mM ammonium. Similarly, the chlorophyll content, photosynthetic rate, and stomatal conductance were significantly increased with 1 mM ammonium treatment. Further, the contents of CK, ABA, and IAA increased first and then decreased, reaching a maximum at 1 mM ammonium. Notably, the “down then up” trend of sucrose content in leaves and stems contrasted with the fall–rise pattern of starch content in SRs at 1 mM ammonium. Furthermore, we screened 34 significant DEGs involved in photosynthesis, starch biosynthetic processes, and hormone signal pathway in SRs by RNA-Seq. All the results indicated that 1 mM ammonium had a promotive effect on source–sink conversion and SR production in Sushu16, which highlights potential targets for breeding or agronomic strategies to optimize yield formation in sweetpotato. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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13 pages, 1714 KiB  
Article
Screening Genipa americana Progenies for Their Ability to Maintain Leaf Vitality Under Severe Dehydration Using Chlorophyll Fluorescence
by Catriane Sousa-Santos, Junior Pastor Pérez-Molina, Amanda Freitas Cerqueira, Ândrea Carla Dalmolin, Álvaro Alves de Almeida, Martielly Santana dos Santos and Marcelo Schramm Mielke
Forests 2025, 16(5), 770; https://doi.org/10.3390/f16050770 - 30 Apr 2025
Viewed by 362
Abstract
Damage to the photosynthetic apparatus during leaf dehydration is an indicator of the maintenance of leaf vitality and the resilience of tree seedlings to severe drought. Genipa americana is a tree widely distributed in the neotropical region but with great ecological and sociocultural [...] Read more.
Damage to the photosynthetic apparatus during leaf dehydration is an indicator of the maintenance of leaf vitality and the resilience of tree seedlings to severe drought. Genipa americana is a tree widely distributed in the neotropical region but with great ecological and sociocultural importance in the south of the state of Bahia, Brazil, where its fruits are harvested from subspontaneous trees. This study aimed to compare the feasibility of the maximum quantum efficiency of photosystem II (Fv/Fm) and performance indexes derived from the JIP test, i.e., performance index on absorption basis (PIabs) and total performance index (PItotal), for screening G. americana seedlings from different mother plants for leaf damage caused by dehydration. From leaf dehydration curves, we calculated the values of relative water content (RWC) in which Fv/Fm, PIabs, and PItotal reach a loss of 10% and 50% in relation to the values of fully hydrated leaves. PItotal was the only parameter that revealed consistent significant differences between progenies for RWC at 50% of percentage loss. Significant differences were observed among progenies for leaf traits; however, no correlation was detected between these traits and chlorophyll fluorescence parameters. Monitoring the PItotal values during leaf dehydration is a useful tool for screening G. americana progenies in relation to their capacity to maintain leaf vitality under occasional severe droughts. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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25 pages, 1518 KiB  
Article
Inorganic and Organic Fertilization Effects on the Growth, Nutrient Uptake, Chlorophyll Fluorescence and Fruit Quality in Solanum melongena L. Plants
by Theocharis Chatzistathis, Virginia Sarropoulou, Evgenia Papaioannou and Anastasia Giannakoula
Agronomy 2025, 15(4), 872; https://doi.org/10.3390/agronomy15040872 - 30 Mar 2025
Viewed by 1200
Abstract
Plant growth, nutrient uptake and fruit quality may be influenced by fertilization practices. A 64-day greenhouse pot experiment, with a 6X1 factorial, i.e., Solanum melongena L. (cv. ‘Lagkadas’) plants, grown on soil substrate and submitted to six fertilization treatments (Patent Kali, Ammonium Nitrate [...] Read more.
Plant growth, nutrient uptake and fruit quality may be influenced by fertilization practices. A 64-day greenhouse pot experiment, with a 6X1 factorial, i.e., Solanum melongena L. (cv. ‘Lagkadas’) plants, grown on soil substrate and submitted to six fertilization treatments (Patent Kali, Ammonium Nitrate + Patent Kali, Tree Branch Chips, Poultry Manure, Tree Branch Chips + Poultry Manure, and non-fertilization—CONTROL) was conducted. The objectives were to investigate the impact of fertilization on: (i) plant growth, (ii) nutrition, (iii) photosystem II activity and (iv) fruit quality. The main results were the following: a) the highest total plant and fruit biomass values were recorded in poultry manure, followed by those in the ammonium nitrate + patent kali treatment; (b) in most cases, total plant macronutrient content was significantly higher in the poultry manure-treated plants; (c) the optimum and most balanced plant nutrition, fruit total phenolic and flavonoid contents and antioxidant activity levels were achieved in the poultry manure, tree branch chips + poultry manure and ammonium nitrate + patent kali treatments; (d) significant decline in the values of the maximum quantum yield of photosystem II, performance index and fruit quality was found in the tree branch chips and CONTROL plants. It was concluded that the kind of fertilization significantly influenced biomass, nutrient uptake, chlorophyll content and fluorescence, as well as fruit quality of Solanum melongena L. plants. Thus, it should be thoroughly investigated, towards substituting high fertilization rates by manure applications and improving fruit quality, with human health benefits. Full article
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8 pages, 475 KiB  
Proceeding Paper
Yield, Morphological Traits, and Physiological Parameters of Organic and Pelleted Avena sativa L. Plants Under Different Fertilization Practices
by Aleksandra Stanojković-Sebić, Dobrivoj Poštić, Marina Jovković and Radmila Pivić
Biol. Life Sci. Forum 2025, 41(1), 4; https://doi.org/10.3390/blsf2025041004 - 27 Mar 2025
Viewed by 325
Abstract
Oat (Avena sativa L.) is one of the most important self-fertilizing field plants belonging to the Poaceae family. It has no significant requirements regarding growing conditions but has a very good reaction to fertilization. The current research evaluated the significance of the [...] Read more.
Oat (Avena sativa L.) is one of the most important self-fertilizing field plants belonging to the Poaceae family. It has no significant requirements regarding growing conditions but has a very good reaction to fertilization. The current research evaluated the significance of the effects of individual applications of mineral (NPK) and organo-mineral (OMF) fertilizers, as well as their individual combination with slaked lime (calcium hydroxide, Ca(OH)2), on the yield, morphological traits [mean number of leaves per plant—MNLP, minimum leaf length (cm) per plant—MinLL, maximum leaf length (cm) per plant—MaxLL, number of ears per plant—NEP], and physiological parameters (nitrogen balance index—NBI, content of chlorophyll—Chl, flavonoids—Flv, anthocyanins—Ant) of organic and pelleted (graded) oat plants, comparing the treatments and in relation to the control. The experiment was performed in semi-controlled glasshouse conditions, in pots, from the fourth week of March to the fourth week of June 2024, using Vertisol soil. This soil is characterized as light clay with an acid reaction. Physiological parameters were measured using a Dualex leaf clip sensor. The results obtained showed that physiological parameters in both oat types significantly differed (p < 0.05) between the treatments applied and in relation to the control, whereas the morphological traits did not significantly differ (p > 0.05) between the treatments. Statistically significant differences (p < 0.05) in the yield of both oat types were most pronounced in the OMF + Slaked Lime treatment (organic: 4.49 g pot−1; pelleted: 4.61 g pot−1) in relation to the control (organic: 2.48 g pot−1; pelleted: 2.63 g pot−1). The pelleted oats showed slightly better results for the effects of different treatments across all tested parameters compared to organic oats. In conclusion, the best results were obtained with the use of OMF + Slaked Lime, which could be proposed as the optimal fertilization treatment for pelleted and organic oat cultivation based on this research. Full article
(This article belongs to the Proceedings of The 4th International Electronic Conference on Agronomy)
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25 pages, 1944 KiB  
Article
Physiological Effects of Mercury on Handroanthus impetiginosus (Ipê Roxo) Plants
by Evandro Alves de Oliveira, Daniela Roberta Borella, Vinícius José Santos Lopes, Leandro Dênis Battirola, Ricardo Lopes Tortorela de Andrade and Andréa Carvalho da Silva
Agronomy 2025, 15(3), 736; https://doi.org/10.3390/agronomy15030736 - 19 Mar 2025
Viewed by 668
Abstract
Mercury (Hg) poses significant risks to human health, the environment, and plant physiology, with its effects influenced by chemical form, concentration, exposure route, and organism vulnerability. This study evaluates the physiological impacts of Hg on Handroanthus impetiginosus (Ipê Roxo) seedlings through SPAD index [...] Read more.
Mercury (Hg) poses significant risks to human health, the environment, and plant physiology, with its effects influenced by chemical form, concentration, exposure route, and organism vulnerability. This study evaluates the physiological impacts of Hg on Handroanthus impetiginosus (Ipê Roxo) seedlings through SPAD index measurements, chlorophyll fluorescence analysis, and Hg quantification in plant tissues. Four-month-old seedlings were exposed for eight days to distilled water containing Hg at 0, 1, 3, 5, and 7 mg L−1. The SPAD index decreased by 28.17% at 3, 5, and 7 mg L−1, indicating reduced photosynthetic capacity. Chlorophyll a fluorescence analysis revealed a 50.58% decline in maximum efficiency (Fv/Fm) and a 58.33% reduction in quantum yield (ΦPSII) at 7 mg L−1, along with an 83.04% increase in non-photochemical quenching (qn), suggesting oxidative stress and PSII damage. Transpiration decreased by 26.7% at 1 mg L−1 and by 55% at 3, 5, and 7 mg L−1, correlating with Hg levels and leaf senescence. Absorption, translocation, bioconcentration, and bioaccumulation factors varied among treatments. Hg accumulated mainly in stems (40.23 μg g−1), followed by roots (0.77 μg g−1) and leaves (2.69 μg g−1), with limited translocation to leaves. These findings highlight Hg’s harmful effects on H. impetiginosus, an ecologically and commercially valuable species, addressing a gap in research on its Hg tolerance and phytoremediation potential. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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19 pages, 2091 KiB  
Article
Effects of Different Irrigation Regimes on Root Growth and Physiological Characteristics of Mulch-Free Cotton in Southern Xinjiang
by Feiyan Su, Ziyang Guo, Bingrong Wu, Jichuan Wang and Shuangrong Chen
Life 2025, 15(3), 435; https://doi.org/10.3390/life15030435 - 10 Mar 2025
Viewed by 647
Abstract
In order to explore the effects of different irrigation methods on the physiological characteristics of mulch-free cotton in southern Xinjiang, the following experiments were carried out: (1) Different irrigation amount test: 300, 375, 450, 525, and 600 mm (represented by W1, W2, W3, [...] Read more.
In order to explore the effects of different irrigation methods on the physiological characteristics of mulch-free cotton in southern Xinjiang, the following experiments were carried out: (1) Different irrigation amount test: 300, 375, 450, 525, and 600 mm (represented by W1, W2, W3, W4, and W5) and a control (450 mm for film-covered cotton, represented by WCK) were set. (2) Drip irrigation frequency test: drip irrigation 12, 10, 8, and 6 times during the growth period (expressed by P12, P10, P8, and P6). Soil water dynamics, root distribution dynamics, chlorophyll fluorescence, leaf area index (LAI), SPAD (chlorophyll density), stress enzyme activities, and MDA (malondialdehyde) content were observed. The results showed that the average maximum change range of soil water content in the cotton field without film mulching was ±17.7%, which was 1.35 times higher than that in the cotton field with film mulching. Compared with cotton with film mulching, the root distribution characteristics of mulch-free cotton in the surface soil (0–20 cm) and the periphery (30 cm from the main root) decreased by 33.55–74.48% and 14.07–102.18%, respectively, while the root distribution characteristics in the deep layer (40–60 cm) increased by 49.62–242.67%, its average leaf green fluorescence parameters decreased by 9.03–50.44%, the activities of protective enzymes (SOD: superoxide dismutase, POD: peroxidase) decreased by 3.36–3.58%, the SPAD value decreased by 5.55%, and the MDA content increased by 3.17%, indicating that mulch-free cotton reduced the physiological function of cotton leaves, and the yield decreased by 42.07%. In the mulch-free treatments, the average root growth indexes were W2 > W3 > W4 > W5 > W1 and P12 > P10 > P8 > P6, and there was little difference between W2 and W3 and P12 and P10. With the increase in irrigation water and irrigation frequency, the initial fluorescence (F0) of leaves in each period of mulch-free cotton showed a downward trend, and the maximum fluorescence (Fm), variable fluorescence (FV), maximum photochemical efficiency (FV/Fm), potential photochemical activity of PS II (FV/F0), electron transfer of PS II (Fm/F0), and photosynthetic performance index (PIABS) showed an upward trend. In all water treatments, W3 and P12 had the highest SPAD value, protective enzyme activity, and the lowest MDA content, which was significantly different from other treatments except W4 and P10. The yield order of different treatments was W3 > W4 > W5 > W2 > W1, and the difference between W3 and W4 was not significant, but significant with W2 and W1. The irrigation frequency test was P12 > P10 > P8 > P6, and there was no significant difference between P12 and P10. We find that in the mulch-free treatment, all indicators of W3, W2, P12, and P10 were relatively high. It can be concluded that no mulching has a certain impact on cotton root distribution and leaf physiological function. When the irrigation amount is 450–525 mm and irrigation times is 10–12, it is beneficial for promoting root growth and plays a role in leaf physiological function, and the water use efficiency (WUE) is high, which can provide reference for the scientific water management of mulch-free cotton in production practice. Full article
(This article belongs to the Special Issue Plant Biotic and Abiotic Stresses 2024)
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23 pages, 5175 KiB  
Article
Prediction of Vegetation Indices Series Based on SWAT-ML: A Case Study in the Jinsha River Basin
by Chong Li, Qianzuo Zhao, Junyuan Fei, Lei Cui, Xiu Zhang and Guodong Yin
Remote Sens. 2025, 17(6), 958; https://doi.org/10.3390/rs17060958 - 8 Mar 2025
Cited by 1 | Viewed by 1152
Abstract
Vegetation dynamics significantly influence watershed ecohydrological processes. Physically based hydrological models often have general plant development descriptions but lack vegetation dynamics data for ecohydrological simulations. Solar-induced chlorophyll fluorescence (SIF) and the Normalized Difference Vegetation Index (NDVI) are widely used in monitoring vegetation dynamics [...] Read more.
Vegetation dynamics significantly influence watershed ecohydrological processes. Physically based hydrological models often have general plant development descriptions but lack vegetation dynamics data for ecohydrological simulations. Solar-induced chlorophyll fluorescence (SIF) and the Normalized Difference Vegetation Index (NDVI) are widely used in monitoring vegetation dynamics and ecohydrological research. Accurately predicting long-term SIF and NDVI dynamics can support the monitoring of vegetation anomalies and trends. This study proposed a SWAT-ML framework, combining the Soil and Water Assessment Tool (SWAT) and machine learning (ML), in the Jinsha River Basin (JRB). The lag effects that vegetation responds to using hydrometeorological elements were considered while using SWAT-ML. Based on SWAT-ML, SIF and NDVI series from 1982 to 2014 were reconstructed. Finally, the spatial and temporal characteristics of vegetation dynamics in the JRB were analyzed. The results showed the following: (1) the SWAT-ML framework can simulate ecohydrological processes in the JRB with satisfactory results (NS > 0.68, R2 > 0.79 for the SWAT; NS > 0.77, MSE < 0.004 for the ML); (2) the vegetation index’s mean value increases (the Z value, the significance indicator in the Mann–Kendall method, is 1.29 for the SIF and 0.11 for the NDVI), whereas the maximum value decreases (Z value = −0.20 for SIF and −0.42 for the NDVI); and (3) the greenness of the vegetation decreases (Z value = −2.93 for the maximum value and −0.97 for the mean value) in the middle reaches. However, the intensity of the vegetation’s physiological activity increases (Z value= 3.24 for the maximum value and 2.68 for the mean value). Moreover, the greenness and physiological activity of the vegetation increase in the lower reaches (Z value = 3.24, 2.68, 2.68, and 1.84 for SIFmax, SIFave, NDVImax, and NDVIave, respectively). In the middle and lower reaches, the connection between the SIF and hydrometeorological factors is stronger than that of the NDVI. This research developed a new framework and can provide a reference for complex ecohydrological simulation. Full article
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22 pages, 2687 KiB  
Article
Industrial Hemp Finola Variety Photosynthetic, Morphometric, Biomechanical, and Yield Responses to K Fertilization Across Different Growth Stages
by Ivana Varga, Antonela Markulj Kulundžić, Paulina Krolo, Dario Iljkić, Marina Tišma and Ivan Kraus
Agronomy 2025, 15(2), 496; https://doi.org/10.3390/agronomy15020496 - 19 Feb 2025
Viewed by 1181
Abstract
The growing interest in Cannabis sativa as a highly used crop is present worldwide. There are limited data about the effect of potassium (K) fertilizer on industrial hemp yield for dual purposes (seed and stem production). The current study aimed to investigate the influence [...] Read more.
The growing interest in Cannabis sativa as a highly used crop is present worldwide. There are limited data about the effect of potassium (K) fertilizer on industrial hemp yield for dual purposes (seed and stem production). The current study aimed to investigate the influence of adding two different K fertilizers, KCl and K2SO4, at two growth stages (flowering and ripening) on the productivity and chlorophyll a fluorescence (ChlF) of Cannabis sativa, variety Finola. Before sowing, different K treatments were applied: K1—100 kg ha−1 KCl (60% K) and K2—100 kg ha−1 K2SO4 (52% K, S 17%). The OJIP (O stands for “origin” (minimal fluorescence), P for “peak” (maximum fluorescence), and J and I for inflection points between the O and P levels) data were recorded and used for ChlF transients and individual ChlF parameters during vegetation. At harvest, the stem morphology parameters and yield (plant height, stem weight and diameter, and stem and seed yield), tensile strength, and the modulus of elasticity were determined. The results show the sensitivity of minimal (F0) and maximal fluorescence (Fm), electron transport from QA to intersystem electron acceptors (ET0/(TR0 − ET0)), and electron transport flux until PSI acceptors (RE0/RC) to K fertilization. The parameters that described electron transport (ET0/RC, ψE0, and φE0), performance index on absorption basis (PIABS, TR0/DI0, and φP0), dissipation (DI0/RC), and electron transport to photosystem I (φR0 and δR0/(1 − δR0)) had a reaction only at the growth stage, indicating a change in their activity during the aging of the Cannabis sativa plants. The average stem height was 67.5 cm, and the stem diameter was 0.41 cm. The different K sources did not significantly influence the stem height and diameter, nor the dry stem (on average 12.2 t ha−1) and seed yield (on average 1.85 t ha−1). The tensile strength of individual hemp stems was the highest with K2SO4 (53.32 MPa) and the lowest with KCl (49.25 MPa). The stem stiffness by modulus of elasticity was about 5 GPa on average for all the treatments. In general, the photosynthetic parameters in this study varied more between the growth stages than between the different K fertilizer formulations. Moreover, based on the results of this study, it can be recommended to use both fertilizers, KCl and K2SO4, in dual-purpose industrial hemp production since no significant effect was found for the stem morphometric and biomechanical parameters as well as for the agronomic parameters. Full article
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15 pages, 3841 KiB  
Article
In-Field Phenotyping Using the Low-Cost and Open Access Fluorescence PhotosynQ Multispeq Sensor Together with NDVI: A Case Study with Durum Wheat
by Adrian Gracia-Romero, Joel Segarra, Fatima Zahra Rezzouk, Nieves Aparicio, Shawn C. Kefauver and José Luis Araus
Agriculture 2025, 15(4), 385; https://doi.org/10.3390/agriculture15040385 - 12 Feb 2025
Cited by 2 | Viewed by 1344
Abstract
Durum wheat production is concentrated in Mediterranean climate regions, making it essential to develop cultivars that adapt to its changing conditions, including water and heat stress. In this regard, photosynthetic capacity estimates may help improve the selection of the most adapted cultivars. However, [...] Read more.
Durum wheat production is concentrated in Mediterranean climate regions, making it essential to develop cultivars that adapt to its changing conditions, including water and heat stress. In this regard, photosynthetic capacity estimates may help improve the selection of the most adapted cultivars. However, the cost and inherent low throughput of the usual methodological approaches makes, in many cases, phenotyping unfeasible, particularly under field conditions. This study uses leaf photosynthetic measurements taken with a low-cost handheld chlorophyll sensor (MultispeQ Photosynq) and a biomass sensitive sensor (GreenSeeker) measuring the normalized difference vegetation index (NDVI) to assess the performance of six modern durum wheat cultivars. The sensors were employed at anthesis and grain filling under two different types of management (rainfed and support irrigation) for two growing seasons. Compared to irrigated plants, rainfed trials had significantly lower photosynthetic performance during the two phenological stages evaluated. Significant genotype differences in steady-state fluorescence yield (Fs) and maximum fluorescence yield (Fm′) across treatments and crop seasons were found. This study shows that leaf chlorophyll fluorescence parameters can be used to select modern wheat cultivars with an open-source, low-cost, handheld sensor (Photosynq). Full article
(This article belongs to the Special Issue Smart Agriculture Sensors and Monitoring Systems for Field Detection)
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24 pages, 4987 KiB  
Article
Synergistic Effects of Biochar and Irrigation on Sugar Beet Growth, Yield, Quality, and Economic Benefit in Arid Regions
by Fuchang Jiang, Yi Li, Liwei Li, Xiangwen Xie, Wanli Xu, Yang Gao and Asim Biswas
Plants 2025, 14(3), 368; https://doi.org/10.3390/plants14030368 - 25 Jan 2025
Viewed by 1072
Abstract
Water scarcity hinders sustainable agriculture in arid and semi-arid regions. This study investigated the combined effects of trickle irrigation and biochar application on sugar beet cultivation in northwest China’s arid and semi-arid regions, addressing challenges of water scarcity. Three-year field experiments were conducted [...] Read more.
Water scarcity hinders sustainable agriculture in arid and semi-arid regions. This study investigated the combined effects of trickle irrigation and biochar application on sugar beet cultivation in northwest China’s arid and semi-arid regions, addressing challenges of water scarcity. Three-year field experiments were conducted using plastic film mulch, four irrigation levels based on crop evapotranspiration (0.6–1.2 ETc), and four biochar application rates (0–30 t ha−1). Results showed that biochar application increased sugar beet germination rates by 7.2–24.5% and enhanced relative chlorophyll content by 3.1–22.1%. Optimal combinations of irrigation and biochar significantly improved growth indices and yield, with maximum values observed under the highest irrigation (1.2 ETc) and 10 t ha−1 biochar treatment. However, the 1.0 ETc irrigation treatment with 10 t ha−1 biochar demonstrated superior water use efficiency (14.8% higher), sustainable yield index (1.1% higher), and economic benefits (1.4% higher) compared to the highest irrigation treatment. Considering growth, yield, quality, water use efficiency, sustainability, and economic factors, an irrigation level of 1.0 ETc combined with a biochar application rate of 10 t ha−1 is recommended for sugar beet cultivation in Xinjiang. This study provides valuable insights and practical strategies for water conservation, high yield, and quality improvement in sugar beet cultivation under arid and semi-arid conditions, contributing to sustainable agricultural practices in water-scarce regions. Full article
(This article belongs to the Special Issue Strategies to Improve Water-Use Efficiency in Plant Production)
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