Effect of plant growth regulators and deficit irrigation on canopy traits, yield, water productivity and fruit quality of eggplant (Solanum melongena L.) grown in the water scarce environment

Drought Stress Tolerance in Vegetables: The Functional Role of Structural Features, Key Gene Pathways, and Exogenous Hormones

The deleterious effects of drought stress have led to a significant decline in vegetable production, ultimately affecting food security. After sensing drought stress signals, vegetables prompt multifaceted response measures, eventually leading to changes in internal cell structure and external morphology. Among them, it is important to highlight that the changes, including changes in physiological metabolism, signal transduction, key genes, and hormone regulation, significantly influence drought stress tolerance in vegetables. This article elaborates on vegetable stress tolerance, focusing on structural adaptations, key genes, drought stress signaling transduction pathways, osmotic adjustments, and antioxidants. At the same time, the mechanisms of exogenous hormones such as abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and ethylene (ET) toward improving the adaptive drought tolerance of vegetables were also reviewed. These insights can enhance the understanding of vegetable drought tolerance, supporting vegetable tolerance enhancement by cultivation technology improvements under changing climatic conditions, which provides theoretical support and technical reference for innovative vegetable stress tolerance breeding and food security.

Effect of Co-Application of Azospirillum brasilense and Rhizobium pisi on Wheat Performance and Soil Nutrient Status under Deficit and Partial Root Drying Stress

Water management techniques are improving at the farm level, but they are not enough to deal with the limited availability of water and increased crop yields. Soil microbes play a vital role in nitrogen fixation, improving soil fertility and enhancing plant growth hormones under drought conditions. Therefore, this study was conducted to investigate the impact of water management combined with Azospirillum brasilense and Rhizobium pisi on wheat crop productivity and soil properties in dry regions. Three water management techniques were compared, normal irrigation as a control (C), deficit irrigation (DI), and partial root drying irrigation (PRD), together with the interaction of plant-growth-promoting rhizobacteria (PGPR). Experiments were conducted with six treatments in total: T1 = C + No PGPR, T2 = C + PGPR, T3 = DI + No PGPR, T4 = DI + PGPR, T5 = PRD + No PGPR, and T6 = PRD + PGPR. The highest grain yield was achieved in the control irrigation treatment using seeds inoculated with rhizobacteria, followed by control treatment without any inoculation, and the lowest was recorded with deficit irrigation without rhizobacteria inoculated in the seeds. However, PRD irrigation resulted in significantly higher plant growth and grain yield than the DI treatment. PGPR inoculation combined with PRD resulted in a 22% and 20% higher number of grains per spike, a 19% and 21% higher grain yield, and a 25% and 22% higher crop growth rate compared to rhizobacteria inoculation combined with the DI system in 2021-22 and 2022-23, respectively. This increase was due to the higher production of growth hormones and higher leaf area index under water-limited conditions. A greater leaf area index leads to a higher chlorophyll content and higher food production for plant growth.

Prasanna S, Vishwanath YC, G. Reddi S, Halli HM, Boraiah KM, Basavaraj PS, Mahmoud EA, Casini R, Elansary HO. Promising Bioregulators for Higher Water Productivity and Oil Quality of Chia under Deficit Irrigation in Semiarid Regions

Appropriate water management practices are essential for the successful cultivation of chia in water-scarce situations of semiarid regions. This is highly essential when new crops such as chia are introduced for ensuring diversity and water saving. Therefore, field trials (2020-21 and 2021-22) were conducted to understand the impact of deficit irrigation and bioregulators (BRs) on the seed yield, water productivity, and oil quality of chia. The effect of foliar application of BRs such as thiourea (TU; 400 ppm), salicylic acid (SA; 1.0 mM), potassium nitrate (KN; 0.15%), potassium silicate (KS; 100 ppm), kaolin (KO; 5%), and sodium benzoate (SB; 200 ppm) were monitored at different levels of irrigation: 100 (I₁₀₀), 75 (I₇₅), 50 (I₅₀), and 25 (I₂₅) percent of cumulative pan evaporation (CPE). Deficit irrigation at I₂₅, I₅₀, and I₇₅ led to 55.3, 20.1, and 3.3% reductions in seed yield; 42.5, 22.5, and 4.2% in oil yield; and 58.9, 24.5, and 5.7% in omega-3 yield, respectively, relative to I₁₀₀. Bioregulators could reduce the adverse impact of water deficit stress on seed, oil, and omega-3 yield. However, their beneficial effect was more conspicuous under mild water stress (I₇₅), as revealed by higher seed yield (4.3-6.9%), oil yield (4.4-7.1%), and omega-3 yield (4.7-8.5%) over control (I₁₀₀ + no BRs). Further, BRs (KN, TU, and SA) maintained oil quality in terms of linolenic acid and polyunsaturated fatty acid contents, even under mild stress (I₇₅). Foliar application of KN, TU, and SA could save water to an extent of 36-40%. Therefore, the adverse impact of deficit irrigation on seed, oil, and omega-3 yields of chia could be minimized using BRs such as KN, TU, and SA, which can also contribute to improved water productivity.

Effect of different soil water managements on the selectivity of fomesafen in conventional and RR soybean

The study aimed to study the selectivity of the herbicide fomesafen, sprayed at different growth stages of the conventional and RR soybean cultivars, under different soil water managements. Two soybean cultivars were used: MG/BR 46 Conquista (conventional) and BRS Valiosa (RR), submitted to the spraying of fomesafen at two phenological stages (V2-first open trefoil; V4-third open trefoil), under three soil water conditions (-0.03, -0.07, and -0.5 MPa). Under water scarcity conditions, soybean plants have lower visual phytotoxicity when subjected to the spraying of the herbicide fomesafen. There were anatomical differences between the leaf blades of the conventional (MG/BR 46 Conquista) and transgenic (BRS Valiosa - RR) cultivars, and the water scarcity changed the anatomy of the soybean plants. The condition of moderate water shortage (-0.07 MPa) led the conventional cultivar to present a lower development than the transgenic cultivar. The transgenic cultivar had a greater ability to sustain the biological nitrogen fixation under moderate water shortage conditions (-0.07 MPa) than the conventional cultivar.

Differential Transcriptomic Regulation in Sweet Orange Fruit (Citrus sinensis L. Osbeck) Following Dehydration and Rehydration Conditions Leading to Peel Damage

Water stress is the most important environmental agent that contributes to the crop productivity and quality losses globally. In citrus, water stress is the main driver of the fruit peel disorders that impact the quality and market ability. An increasingly present post-harvest peel disorder is non-chilling peel pitting (NCPP). Non-chilling peel pitting is manifested as collapsed areas of flavedo randomly scattered on the fruit and its incidence increases due to abrupt increases in the environmental relative humidity (RH) during post-harvest fruit manipulation. In this study, we have used a custom-made cDNA microarray containing 44k unigenes from Citrus sinensis (L. Osbeck), covering for the first time the whole genome from this species, to study transcriptomic responses of mature citrus fruit to water stress. In the study, the global gene expression profiles of flavedo from Navelate oranges subjected to severe water stress are compared with those fruits subjected to rehydration stress provoked by changes in the RH during post-harvest, which enhances the development of NCPP. The study results show that NCPP is a complex physiological process that shares molecular responses with those from prolonged dehydration in fruit, but the damage associated with NCPP may be explained by unique features of rehydration stress at the molecular level, such as membrane disorganization, cell wall modification, and proteolysis.

Thiourea supplementation mediated reduction of grain arsenic in rice (Oryza sativa L.) cultivars: A two year field study

The present study delineates the interactions of arsenic (As), a carcinogenic metalloid, and thiourea (TU), a non-physiological reactive oxygen species (ROS) scavenger, in rice plants grown in As contaminated fields in West Bengal, India. The study was performed for four consecutive seasons (two boro and two aman) in 2016 and 2017 with two local rice cultivars; Gosai and Satabdi (IET-4786) in a control and two As contaminated experimental fields. Thiourea (0.05% wt/vol) treatment was given in the form of seed priming and foliar spray. Thiourea significantly improved growth and yield of rice plants and reduced As concentration in root, shoot, husk and grains in both cultivars and fields. The reduction in As concentration ranged from 10.3% to 27.5% in four seasons in different fields. The average (four seasons) increase in yield was recorded about ~8.1% and ~11.5% in control, ~20.2% and ~18.6% in experimental field 1, and ~16.2% and ~24.1% in experimental field 2, for gosai and satabdi, respectively. Mean hazard quotient (HQ) and incremental lifetime cancer risk (ILCR) values of As reduced upon TU supplementation for both cultivars as compared to that of non-TU plants. Hence, TU can be effectively used to cultivate rice safely in As contaminated fields.