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Improving cropping systems together with suitable agronomic management practices can maintain dry farming productivity and reduce water competition with low N inputs. The objective of the study was to determine the photosynthetic and yield responses of maize and peanut under six treatments: sole maize, sole peanut, maize–peanut intercropping, maize–peanut rotation–intercropping, 20% and 40% N reductions for maize in the maize–peanut rotation–intercropping. Maize–peanut intercropping had no land-use advantage. Intercropped peanut is limited in carboxylation rates and electron transport rate (ETR), leading to a decrease in hundred-grain weight (HGW) and an increase in blighted pods number per plant (NBP). Intercropped peanut adapts to light stress by decreasing light saturation point (Isat) and light compensation point (Icomp) and increasing the electron transport efficiency. Intercropped maize showed an increase in maximum photosynthetic rate (Pnmax) and Icomp due to a combination of improved intercellular CO2 concentration, carboxylation rates, PSII photochemical quantum efficiency, and ETR. Compare to maize–peanut intercropping, maize–peanut rotation–intercropping alleviated the continuous crop barriers of intercropped border row peanut by improving carboxylation rates, electron transport efficiency and decreasing Isat, thereby increasing its HGW and NBP. More importantly, the land equivalent ratio of maize–peanut rotation–intercropping in the second and third planting years were 1.05 and 1.07, respectively, showing obvious land use advantages. A 20% N reduction for maize in maize–peanut rotation–intercropping does not affect photosynthetic character and yield for intercropped crops. However, a 40% N reduction decreased significantly the carboxylation rates, ETR, Icomp and Pnmax of intercropped maize, thereby reducing in a 14.83% HGW and 5.75% lower grain number per spike, and making land-use efficiency negative.

Rising atmospheric CO2 concentrations are known to influence the response of many plants under drought. This paper aimed to measure the leaf gas exchange, water use efficiency, carboxylation efficiency, and photosystem II (PS II) activity of Datura stramonium under progressive drought conditions, along with ambient conditions of 400 ppm (aCO2) and elevated conditions of 700 ppm (eCO2). Plants of D. stramonium were grown at 400 ppm and 700 ppm under 100 and 60% field capacity in a laboratory growth chamber. For 10 days at two-day intervals, photosynthesis rate, stomatal conductance, transpiration rate, intercellular CO2 concentration, water use efficiency, intrinsic water use efficiency, instantaneous carboxylation efficiency, PSII activity, electron transport rate, and photochemical quenching were measured. While drought stress had generally negative effects on the aforementioned physiological traits of D. stramonium, it was found that eCO2 concentration mitigated the adverse effects of drought and most of the physiological parameters were sustained with increasing drought duration when compared to that with aCO2. D. stramonium, which was grown under drought conditions, was re-watered on day 8 and indicated a partial recovery in all the parameters except maximum fluorescence, with this recovery being higher with eCO2 compared to aCO2. These results suggest that elevated CO2 mitigates the adverse growth effects of drought, thereby enhancing the adaptive mechanism of this weed by improving its water use efficiency. It is concluded that this weed has the potential to take advantage of climate change by increasing its competitiveness with other plants in drought-prone areas, suggesting that it could expand into new localities.

In recent years, heavy metals-induced soil pollution has increased due to the widespread usage of chromium (Cr) in chemical industries. The release of Cr into the environment has reached its peak causing hazardous environmental pollution. Heavy metal-induced soil pollution is one of the most important abiotic stress affecting the dynamic stages of plant growth and development. In severe cases, it can kill the plants and their derivatives and thereby pose a potential threat to human food safety. The chromium ion effect on plants varies and depends upon its severity range. It mainly impacts the numerous regular activities of the plant's life cycle, by hindering the germination of plant seeds, inhibiting the growth of hypocotyl and epicotyl parts of the plants, as well as damaging the chloroplast cell structures. In this review article, we tried to summarize the possible effects of chromium-induced stress on plant growth, developmental physiology, biochemistry, and molecular regulation and provided the important theoretical basis for selecting remedial plants in chromium-induced contaminated soils, breeding of low toxicity tolerant varieties, and analyzing the mechanism of plant resistance mechanisms in response to heavy metal stress.

Cotton is a major fiber crop grown worldwide. Nitrogen (N) is an essential nutrient for cotton production and supports efficient crop production. It is a crucial nutrient that is required more than any other. Nitrogen management is a daunting task for plants; thus, various strategies, individually and collectively, have been adopted to improve its efficacy. The negative environmental impacts of excessive N application on cotton production have become harmful to consumers and growers. The 4R’s of nutrient stewardship (right product, right rate, right time, and right place) is a newly developed agronomic practice that provides a solid foundation for achieving nitrogen use efficiency (NUE) in cotton production. Cropping systems are equally crucial for increasing production, profitability, environmental growth protection, and sustainability. This concept incorporates the right fertilizer source at the right rate, time, and place. In addition to agronomic practices, molecular approaches are equally important for improving cotton NUE. This could be achieved by increasing the efficacy of metabolic pathways at the cellular, organ, and structural levels and NUE-regulating enzymes and genes. This is a potential method to improve the role of N transporters in plants, resulting in better utilization and remobilization of N in cotton plants. Therefore, we suggest effective methods for accelerating NUE in cotton. This review aims to provide a detailed overview of agronomic and molecular approaches for improving NUE in cotton production, which benefits both the environment and growers.

Nitrogen is a vital nutrient for agricultural, and a defieciency of it causes stagnate cotton growth and yield penalty. Farmers rely heavily on N over-application to boost cotton output, which can result in decreased lint yield, quality, and N use efficiency (NUE). Therefore, improving NUE in cotton is most crucial for reducing environmental nitrate pollution and increasing farm profitability. Well-defined management practices, such as the type of sources, N-rate, application time, application method, crop growth stages, and genotypes, have a notable impact on NUE. Different N formulations, such as slow and controlled released fertilizers, have been shown to improve N uptake and, NUE. Increasing N rates are said to boost cotton yield, although high rates may potentially impair the yield depending on the soil and environmental conditions. This study comprehensively reviews various factors including agronomic and environmental constraints that influence N uptake, transport, accumulation, and ultimately NUE in cotton. Furthermore, we explore several agronomic and molecular approaches to enhance efficiency for better N uptake and utilization in cotton. Finally, this objective of this review to highlight a comprehensive view on enhancement of NUE in cotton and could be useful for understanding the physiological, biochemical and molecular mechanism of N in cotton.

Predicting the germination behavior of parthenium weed against different conditions of temperature and osmotic stress is helpful for studying the growth and development history of parthenium in different ecological contexts. Sustainable weed control strategies based on population-based threshold (PBT) models are profitable tools for crop planting date, herbicide application, and tillage operation time. To predict the emergence of parthenium by using thermal time (TT), hydrotime (HT), and hydrothermal time (HTT) analyses, seeds were exposed to varying constant temperatures (5, 10, 15, 20, 25, 30, 35, and 40°C) and water potentials (− 0.25, − 0.5, − 0.75, and − 1.0 MPa) under a controlled environment. Parthenium seeds showed better responses in terms of higher germination percentage and lower germination time at 20 and 25°C. The use of the germination modeling approach proposed the base temperature (7.2°C), optimum temperature (20°C), and ceiling temperature (42.8°C) for this weed. Moreover, germination behavior was also studied at different water potentials under different temperature regimes (10, 20, and 30°C). The HTT model predicted higher germination percentages (82.8 and 54.8%) of parthenium seeds at water potentials from 0 to −0.25 MPa, respectively, under a temperature of 20°C, and also identified a base water potential (Ψb(50) of − 0.54 MPa for germination. In conclusion, the use of the HTT modeling approach is helpful for predicting the emergence response of parthenium in a changing climate and ultimately supportive in time scheduling of parthenium weed management in cropping systems.

This study explains the scarce information on the role of harzianopyridone (HZRP) in the alleviation of chromium (Cr) stress alleviation in Vigna radiata (L.). To this end, V. radiata seedlings primed with HZRP at 1 and 2 ppm were exposed to 50 mg kg–1 Cr for 30 days. Cr stress reduced growth, chlorophyll (Chl) content, net photosynthetic rate, gas-exchange attributes along with enhanced oxidative damages, i.e., electrolyte leakage (EL), hydrogen peroxide (H2O2), and malondialdehyde (MDA). Application of HZRP enhanced intercellular carbon dioxide (CO2) concentration, stomatal conductance, and net photosynthetic rate with decreased activity of the chlorophyllase (Chlase) enzyme in V. radiata seedlings exposed to Cr stressed conditions. To maintain Cr-induced oxidative damages, HZRP treatment increased the levels of antioxidant metabolites (phenolic and flavonoids) and the activity of antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)] in V. radiata seedlings grown in normal and Cr-polluted potted soil. In addition to this, glycine betaine content was also increased in plants grown in Cr-contaminated soil. It is proposed the potential role of supplementation of HZRP in mitigating Cr stress. Further research should be conducted to evaluate the potential of HZRP in the mitigation of abiotic stresses in plants.

Due to limited conventional energy sources, there is a need to find substitute non-conventional sources of energy to meet the societal demands on a sustainable basis. Crude oil and edible oil remain major import items in Pakistan, the deficit of which can be compensated by using biomass, preferably inedible oilseeds. Therefore, the current study evaluated the role of sulfur (S) fertilization for improving yield (seed and oil) and biodiesel value of castor bean, a potential inedible crop with minimum input requirements. For this purpose, a combined approach of field experimentation and laboratory analysis was conducted to explore the potential of two castor bean cultivars (DS-30 and NIAB Gold) against four S supply rates, namely, 0, 20, 40, and 60 kg S ha–1, in terms of growth, phenology, and yield parameters. Subsequently, the obtained seed samples were analyzed for biodiesel-related parameters in the Bio-analytical Chemistry lab, Punjab Bio-energy Institute, Faisalabad. The incremental S rates increased the seed yield for both cultivars, and the highest yield was recorded at 60 kg S ha–1 for NIAB Gold. For NIAB Gold, the oil content increased by 7% with S fertilization at 60 kg ha–1, and for DS-30, the oil content increased by 6% at 60 kg ha–1. As with incremental S fertilization, the oil yield increased on a hectare basis, and the quantity of biodiesel produced also increased. Importantly, the tested quality parameters of biodiesel, except biodiesel viscosity, were in the ASTM standard range. Overall, it has been concluded that castor bean is a promising and sustainable option for producing biodiesel as it is non-competitive to food crops and requires little input.

Globally, climate change could hinder future food security that concurrently implies the importance of investigating drought stress and genotype screening under stressed environments. Hence, the current study was performed to screen 45 diverse maize inbred lines for 18 studied traits comprising phenological, physiological, morphological, and yield characters under optimum and water stress conditions for two successive growing seasons (2018 and 2019). The results showed that growing seasons and water regimes significantly influenced (p < 0.01) most of the studied traits, while inbred lines had a significant effect (p < 0.01) on all of the studied traits. The findings also showed a significant increase in all studied characters under normal conditions compared to drought conditions, except chlorophyll content, transpiration rate, and proline content which exhibited higher levels under water stress conditions. Furthermore, the results of the principal component analysis indicated a notable distinction between the performance of the 45 maize inbred lines under normal and drought conditions. In terms of grain yield, the drought tolerance index (DTI) showed that Nub60 (1.56), followed by Nub32 (1.46), Nub66 (1.45), and GZ603 (1.44) were the highest drought-tolerant inbred lines, whereas Nub46 (0.38) was the lowest drought-tolerant inbred line. These drought-tolerant inbred lines were able to maintain a relatively high grain yield under normal and stress conditions, whereas those drought-sensitive inbred lines showed a decline in grain yield when exposed to drought conditions. The hierarchical clustering analysis based on DTI classified the forty-five maize inbred lines and eighteen measured traits into three column- and row-clusters, as inbred lines in cluster-3 followed by those in cluster-2 exhibited greater drought tolerance in most of the studied traits. Utilizing the multi-trait stability index (MTSI) criterion in this study identified nine inbred lines, including GZ603, as stable genotypes in terms of the eighteen studied traits across four environments. The findings of the current investigation motivate plant breeders to explore the genetic potential of the current maize germplasm, especially in water-stressed environments.

WRKY transcription factors (TFs) are essential players in different signaling cascades and regulatory networks involved in defense responses to various stressors. This study systematically analyzed and characterized WRKY family genes in the Saccharum spp. hybrid R570 and their expression in two sugarcane cultivars LCP85-384 (resistant to leaf scald) and ROC20 (susceptible to leaf scald) in response to bacterial pathogen infection and nitrogen implantation dosage. A total of 53 ShWRKY genes with 66 alleles were systematically identified in R570 based on the query sequence SsWRKY in S. spontaneum AP85-441. All ShRWKY alleles were further classified into four groups with 11 (16.7%) genes in group I, 36 (54.5%) genes in group II, 18 (27.3%) genes in group III, and 1 (1.5%) gene in group IV. Among them, 4 and 11 ShWRKY gene pairs displayed tandem and segmental duplication events, respectively. The ShWRKY genes exhibited conserved DNA-binding domains, which were accompanied by variations in introns, exons, and motifs. RT-qPCR analysis of two sugarcane cultivars triggered by Xanthomonas albilineans (Xa) revealed that four genes, ShWRKY13-2/39-1/49-3/125-3, exhibited significant upregulation in leaf scald-resistant LCP85-384. These WRKY genes were downregulated or unchanged in ROC20 at 24–72 h post-inoculation, suggesting that they play an important role in defense responses to Xa infection. Most of the 12 tested ShWRKYs, ShWRKY22-1/49-3/52-1 in particular, functioned as negative regulators in the two cultivars in response to a range of nitrogen (N) implantation doses. A total of 11 ShWRKY proteins were predicted to interact with each other. ShWRKY43 and ShWRKY49-3 are predicted to play core roles in the interaction network, as indicated by their interaction with six other ShWRKY proteins. Our results provide important candidate gene resources for the genetic improvement of sugarcane and lay the foundation for further functional characterization of ShWRKY genes in response to coupling effects of Xa infection and different N levels.

The intensive use of chemical fertilizers in arable farming dramatically increased environmental pollution through anthropogenic ammonia (NH3) and greenhouse gaseous emissions. Therefore, there is a need to develop improved fertilizer management practices that can reduce these losses. An experiment was conducted to assess the mitigating effects of sole or combined application of zeolite with biochar on gaseous emissions from arable land. For this purpose, zeolite (clinoptilolite) was mixed with different doses of biochar (produced from Dalbergia Sissoo wood chips) and applied along with the recommended dose of chemical fertilizer (NPK @ 150, 100, and 60 kg ha–1, respectively) on arable land in years 2013–14 and 2014–15. Immediately after application, these were incorporated into the top 10 cm of the soil layer and wheat was sown. Treatments were as follows: C = control, Z = zeolite @ 5 t ha–1, B1Z = biochar @ 3 t ha–1 + zeolite @ 5 t ha–1, B2Z = biochar @ 6 t ha–1 + zeolite @ 5 t ha–1, and B3Z = biochar @ 9 t ha–1 + zeolite @ 5 t ha–1. The experiment was laid out in a randomized complete block design (RCBD) with three replicates. The experimental plot size was 6 m × 4 m. Randomly, ten soil samples from each plot were taken at a depth of 0–15 cm and mixed to get a composite sample. All the samples were immediately stored in a freezer at −18°C until gaseous analysis in order to prevent N transformations. Each soil sample was analyzed for emission of NH3, CO2, and CH4 by using a selected-ion flow-tube mass spectrometer (SIFT-MS). Co-application of zeolite and biochar reduced NH3 and CH4 emissions by an average of 87 and 58% compared to the control, respectively. However, CO2 emission was increased by 104% relative to the control. The NH3 emission was decreased by an average of 61, 78, 90, and 92% by Z, B1Z, B2Z, and B3Z treatments compared to the control. Similarly, the decrement in CH4 emission was 47, 54, 55, and 65%. In contrast, the increment in CO2 emission was 42, 110, and 160% for B1Z, B2Z, and B3Z, respectively, while interestingly, a reduction of 12% was observed in Z treatment. Besides, co-application of zeolite and biochar at the highest dose (B3Z) improved soil chemical properties such as soil EC, OM, total N, as well as available P and K relative to zeolite alone. It is concluded that the combined application of zeolite and biochar can mitigate NH3 and greenhouse emissions and improve soil chemical characteristics, thus enhancing the environmental worth of arable farming.

Nitrogen (N) fertilization plays a pivotal role in physiomorphological attributes and yield formation of field-grown cotton (Gossypium hirsutum L.), but little is known of its interaction with irrigation levels. Therefore, this study was conducted with an objective of evaluating the impact of irrigation and nitrogen levels on growth attributes and nitrogen use efficiency of Bt cotton (Gossypium spp.) in the hot arid region. The experiment consisted of a factorial arrangement of three irrigation levels (200, 400, and 600 mm) and four nitrogen rates (0, 75, 150, and 225 kg ha–1) in a split-plot design with three replications. Nitrogen fertilization and irrigation levels influenced cotton growth attributes and yield. The highest leaf area index, dry matter accumulation, crop growth rate, and relative growth rate were achieved at 225 kg N ha–1 and irrigation level 600 mm as compared to other experimental treatments. Similarly, nitrogen uptake and content by seed, lint, and stalk and total nitrogen uptake recorded maximum at 225 kg N ha–1 and irrigation level 600 mm. Interestingly, the treatment of 600 mm of irrigation and 150 kg N ha–1 displayed significant increase in nitrogen use efficiency indices such as agronomic efficiency of nitrogen (AEN) and recovery efficiency of nitrogen (REN), while partial factor productivity of nitrogen (PFPN) and internal nitrogen use efficiency (iNUE) were significantly higher with application of 600 mm of irrigation and nitrogen application rate of 75 kg ha–1. Application of 600 mm of irrigation along with 225 kg N ha–1 resulted in significant increase in gross return, net return, and B:C ratio than any other treatment combinations. So, application of 600 mm of irrigation along with 225 kg N ha–1 could be recommended for achieving higher growth and yield, as well as profitability of Bt cotton under hot arid region and similar agroecologies.

The efficiency with which plants use nutrients to create biomass and/or grain is determined by the interaction of environmental and plant intrinsic factors. The major macronutrients, especially nitrogen (N), limit plant growth and development (1.5–2% of dry biomass) and have a direct impact on global food supply, fertilizer demand, and concern with environmental health. In the present time, the global consumption of N fertilizer is nearly 120 MT (million tons), and the N efficiency ranges from 25 to 50% of applied N. The dynamic range of ideal internal N concentrations is extremely large, necessitating stringent management to ensure that its requirements are met across various categories of developmental and environmental situations. Furthermore, approximately 60 percent of arable land is mineral deficient and/or mineral toxic around the world. The use of chemical fertilizers adds to the cost of production for the farmers and also increases environmental pollution. Therefore, the present study focused on the advancement in fertilizer approaches, comprising the use of biochar, zeolite, and customized nano and bio-fertilizers which had shown to be effective in improving nitrogen use efficiency (NUE) with lower soil degradation. Consequently, adopting precision farming, crop modeling, and the use of remote sensing technologies such as chlorophyll meters, leaf color charts, etc. assist in reducing the application of N fertilizer. This study also discussed the role of crucial plant attributes such as root structure architecture in improving the uptake and transport of N efficiency. The crosstalk of N with other soil nutrients plays a crucial role in nutrient homeostasis, which is also discussed thoroughly in this analysis. At the end, this review highlights the more efficient and accurate molecular strategies and techniques such as N transporters, transgenes, and omics, which are opening up intriguing possibilities for the detailed investigation of the molecular components that contribute to nitrogen utilization efficiency, thus expanding our knowledge of plant nutrition for future global food security.

Developing a nitrogen fertilizer (N) reduction method under straw incorporation is essentially important for increasing wheat productivity in terms of improved fertilizer use efficiency and high yield in semiarid areas. A two-year field experiment, with five different nitrogen application rates: control (without N application, N0), low N (75 kg ha–1, N75), medium N (150 kg ha–1, N150), high N (225 kg ha–1, N225) and excessive N (300 kg ha–1, N300), was conducted in 2018 and 2019 to quantify their impacts on the photosynthetic characteristics, nitrogen utilization (in terms of N accumulation, distribution and transportation, and residual soil NO3–-N) and productivity of winter wheat. There was a significant impact of N rates on photosynthetic traits, and N accumulation in different organs. As compared with the N300, N150, and N225 improved the photosynthetic characteristics, increased N accumulation in grains by 5.55 and 10.97%, the N contribution proportion of that accumulated after anthesis by 67.90 and 115.56%, and reduced residual N by 62.50 and 46.48%, respectively, thereby effectively improved N absorption efficiency and N contribution rates. Grain yield remained slightly or unchanged among N treatments. Although N0 and N75 treatments reduced the nitrate-N leaching but caused a significant reduction of 18.13 and 28.37%, respectively, in grain yield. From these results, we conclude that N application at 150 and 225 kg⋅ha–1 under straw incorporation was the most effective fertilization method in achieving the higher photosynthetic characteristics, improving NUE and grain yield. This study provides theoretical and practical guidance for wheat production techniques.

The application of nanoparticles (NPs) has been proved as an efficient and promising technique for mitigating a wide range of stressors in plants. The present study elucidates the synergistic effect of iron oxide nanoparticles (IONPs) and silicon nanoparticles (SiNPs) in the attenuation of Cd toxicity in Phaseolus vulgaris. Seeds of P. vulgaris were treated with IONPs (10 mg/L) and SiNPs (20 mg/L). Seedlings of uniform size were transplanted to pots for 40 days. The results demonstrated that nanoparticles (NPs) enhanced growth, net photosynthetic rate, and gas exchange attributes in P. vulgaris plants grown in Cd-contaminated soil. Synergistic application of IONPs and SiNPs raised not only K+ content, but also biosynthesis of polyamines (PAs), which alleviated Cd stress in P. vulgaris seedlings. Additionally, NPs decreased malondialdehyde (MDA) content and electrolyte leakage (EL) in P. vulgaris plants exposed to Cd stress. These findings suggest that stress alleviation was mainly attributed to the enhanced accumulation of K+ content, improved antioxidant defense system, and higher spermidine (Spd) and putrescine (Put) levels. It is suggested that various forms of NPs can be applied synergistically to minimize heavy metal stress, thus increasing crop production under stressed conditions.

Nitrogen (N) is one of the essential nutrients for plant growth. Appropriate application of N can improve the N use efficiency (NUE) and significantly promote plants’ growth. However, under N toxic conditions, the relationship between the growth and antioxidant system of invasive plants under different N forms and competitive treatments is not fully understood. Therefore, in this study, the performance of invasive species Wedelia trilobata and its native species Wedelia chinensis was evaluated under two sets of N forms and ratios, namely, NH4+-N(AN)/NO3–-N(NN) = 2:1 and NH4+-N(AN)/NO3–-N(NN) = 1:2 along with two intraspecific and interspecific competitions under without N and high N level of 15 g N⋅m–2 year–1, respectively. Data regarding the growth indices, antioxidant enzyme activities, including peroxidase (POD) and catalase (CAT), malondialdehyde (MDA), and proline contents were determined. Results showed that for competitive treatments, growth status was better for interspecific competition than intraspecific competition. The plant biomass of W. trilobata was significantly higher than that of W. chinensis. N significantly promoted the plants’ growth in terms of leaf area and biomass yield, and the antioxidant enzyme activities were significantly increased under a high N treatment than that of the control. Among N forms/ratios, ammonium N (AN)/nitrate N (NN) = 2:1 significantly enhanced the enzyme activity, particularly in W. trilobata. Furthermore, for intraspecific competition, MDA contents of W. trilobata were significantly decreased compared to that of W. chinensis. In conclusion, our results showed that W. trilobata adapted well under competitive conditions through better growth and antioxidant defense system.

Plant growth regulators are naturally biosynthesized chemicals in plants that influence physiological processes. Their synthetic analogous trigger numerous biochemical and physiological processes involved in the growth and development of plants. Nowadays, due to changing climatic scenario, numerous biotic and abiotic stresses hamper seed germination, seedling growth, and plant development leading to a decline in biological and economic yields. However, plant growth regulators (PGRs) can potentially play a fundamental role in regulating plant responses to various abiotic stresses and hence, contribute to plant adaptation under adverse environments. The major effects of abiotic stresses are growth and yield disturbance, and both these effects are directly overseen by the PGRs. Different types of PGRs such as abscisic acid (ABA), salicylic acid (SA), ethylene (ET), and jasmonates (JAs) are connected to boosting the response of plants to multiple stresses. In contrast, PGRs including cytokinins (CKs), gibberellins (GAs), auxin, and relatively novel PGRs such as strigolactones (SLs), and brassinosteroids (BRs) are involved in plant growth and development under normal and stressful environmental conditions. Besides, polyamines and nitric oxide (NO), although not considered as phytohormones, have been included in the current review due to their involvement in the regulation of several plant processes and stress responses. These PGRs are crucial for regulating stress adaptation through the modulates physiological, biochemical, and molecular processes and activation of the defense system, upregulating of transcript levels, transcription factors, metabolism genes, and stress proteins at cellular levels. The current review presents an acumen of the recent progress made on different PGRs to improve plant tolerance to abiotic stress such as heat, drought, salinity, and flood. Moreover, it highlights the research gaps on underlying mechanisms of PGRs biosynthesis under stressed conditions and their potential roles in imparting tolerance against adverse effects of suboptimal growth conditions.

Cotton has prime importance in the global economy and governs socio-economic affairs of the world. Water scarcity and high temperature are major constraints that badly affect cotton production, which shows the need for the development of drought-tolerant varieties. Ten cotton genotypes, including three drought-tolerant and seven susceptible, were identified from a panel of diverse cotton genotypes at the seedling stage under two contrasting water regimes. Three lines were crossed with seven testers under line × tester mating design. The 21 F1 cross combinations along with 10 parents were evaluated under 100% non-stress (NS) and 50% drought stress (DS) filed capacity to assess the effects of drought stress and its inheritance in the next generation. All the genotypes were evaluated till the maturity stage for combining ability, heritability, and other genetic factors to understand the drought tolerance mechanisms. The proportional contribution of lines in the total variance evidenced that lines had a significant higher contribution in total variance for days to boll opening (DBO) of 10% and proline contents (PC) of 13% under DS conditions. It indicates that lines contributed more positive alleles for such traits. Under DS condition, DTV-9 × BT-252 and DTV-9 × DTV-10 had maximum negative specific combining ability (SCA) effects for DBO. Simultaneously, DBO also had higher heritability (h2) which indicates its dominant gene action and meanwhile, the importance of these combinations for the early mature and short duration variety development. The results revealed that most of the studied traits, including days taken to maturity, yield traits, and physiological traits, are under significant genetic control, with a strong genetic basis and have a huge potential for improving drought tolerance in cotton. Drought tolerance was found to have a strong association with early maturity and agro-climatic conditions of the cultivated areas. Identified superior parents in this study are suggested to use in the future breeding program to advance the cotton growth and drought tolerance.

Temperature is a key factor influencing plant growth and productivity, however sudden increases in temperature can cause severe consequences in terms of crop performance. We evaluated the influence of elementary sulfur application on the physiology and growth of two tomato genotypes (“Ahmar” and “Roma”) grown in two growth chambers (at 25 and 45 °C). Plants were sprayed with 2, 4, 6, and 8 ppm sulfur 45 days after sowing (untreated plants were kept as control). Plants of the “Roma” cultivar receiving 6 ppm sulfur exhibited maximal shoot and root biomass values followed by those receiving 4 ppm under both temperature conditions. Maximal CO2 index, photosynthetic rate, transpiration rate, and greenness index values (188.1 µmol mol−1, 36.3 µmol CO2 m−2 s−1, 1.8 µmol H2O m−2 s−1, and 95 SPAD, respectively) were observed in plants of “Roma” cultivar grown at 25 °C, indicating positive influences of sulfur on tomato physiology. Similarly, sulfur maximized proline, nitrogen, phosphorus, and potassium contents in leaves of both genotypes at both temperatures. The differences between control and sulfur-treated plants grown under heat stress indicate a possible role of sulfur in mitigating heat stress. Overall, our results suggest that 6 ppm of sulfur is the best dose to alleviate tomato heat stress and enhance the morphological, physiological, and biochemical attributes of tomato plants.