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Salinity stress is a major threat to cotton growth and productivity worldwide. This study evaluated a diverse collection of fifty cotton genotypes at critical seedling stage using analysis of variance and principal component analysis. The seedlings were subjected to 10dSm-1 and 17dSm-1 salt stress levels starting from the 10th day after sowing until the 42nd days. Data was collected on morphological (root length, shoot length, fresh and dry weights of root and shoot, fresh and dry weight of whole plant) and biochemical (K+, Na+, K+/Na+) parameters. Significant variations were observed among the cotton genotypes for the evaluated traits under control and salt stress conditions. The results revealed that salinity stress had detrimental effects on various growth parameters, including root length, shoot length, fresh root weight, fresh shoot weight, dry shoot weight, dry root weight, and whole plant dry weight. Additionally, sodium levels exhibited a substantial increase under NaCl-induced stress, whereas potassium levels experienced reductions in the leaves. Based on multivariate analysis, the genotypes NIAB - 545, FH- Kehkshan, FH-490, and GH-Mubarak displayed notable salt tolerance likely due to mechanisms such as ion exclusion, osmotic adjustment and tissue tolerance at both 10 dSm-1 and 17 dSm-1 levels. Conversely, the genotypes FH-303, FH-532, FH-542, and SB-149 were deemed salt-sensitive. These findings underscore the challenges associated with selection for salt tolerance in cotton due to the potential masking effects of environmental factors on genetic expression. This study discovers potential salt-tolerant cotton genotypes for use in breeding programs to increase yields under saline stress. However, all genotype-environment interactions must be explored. Overall, these findings provide useful information about salt stress responses in cotton seedlings. [ABSTRACT FROM AUTHOR]

High temperature stress at reproductive stages of cotton crop severely affects the yield and quality of cotton crop under changing climatic conditions. To alleviate the adverse effects of high temperature stress on cotton crop, the regulatory effects of potassium (K), zinc (Zn), and boron (B) were assessed by applying different temperature regimes at three reproductive stages of cotton crop under field and glass house conditions. Cotton plants were subjected to low (32/20 °C ± 2), medium (38/24 °C ± 2), and high (45/30 °C ± 2) temperatures under glasshouse, but sown at specific dates in field to provide different temperatures at three reproductive stages. High-temperature stress at squaring, flowering and boll formation stages in both field studies increased relative cell injury (RCI), total soluble proteins (TSP), reactive oxygen species and reduced fiber yield attributes i.e. total number of bolls per plant (TNBPP), number of sympodial branches per plant (NSBPP) and quality traits. For example, RCI, TNBPP and fiber fineness were reduced by 73%, 42% and 29%, respectively under supra thermal regime (SupTR) of glass house study over the optimal thermal regime (OpTR). Foliar application of K and Zn followed by B increased TSP, RWC, TNBPP, NSBPP, fiber fineness, fiber length and fiber strength. Further, foliar spray of K and Zn followed by B also reduced H2 O2 under SupTR and SubTR over the OpTR. The findings of the present study clearly demonstrate that foliar spray of Zn, K and B alleviated adverse effects of high temperature stress at squaring, flowering and boll formation stages and increased seed cotton yield and quality of cotton crop. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) is one of the most important cash crops primarily grown for fiber. It is a perennial crop with indeterminate growth pattern. Nitrogen (N) is extremely important for vegetative growth as balanced N-nutrition improves photosynthesis, resulting in better vegetative growth. Excessive N-supply results in more vegetative growth, which increases the incidence of insect pest and diseases' infestation, pollute surface and ground water, delays maturity and produces low crop yield with poor quality. The use of plant growth regulators (PGRs) is an emerging option to control excessive vegetative growth. The PGRs help in improving plant architecture, boll retention, boll opening, yield and quality by altering growth and physiological processes such as photosynthesis, assimilate partitioning and nutrients dynamic inside the plant body. Mepiquat chloride (1,1-dimethylpiperidinum chloride) is globally used PGR for canopy development and control of excessive vegetative growth in cotton. This study investigated the effect of mepiquat chloride (MC) and N application on yield and yield components of transgenic cotton variety 'BT-FSH-326'. Two N rates (0, 198 kg ha-1) and five MC rates (0, 30,60, 90 and 120 g ha-1) were included in the study. Results revealed that MC and N application improved boll weight, number of bolls per plant, and seed cotton and lint yields. The highest seed cotton and lint yields (3595 kg ha-1 and 1701 kg ha-1, respectively) were observed under foliar application of 198 kg ha-1 N and 120 g ha-1 MC. Fiber length, fiber strength, micronaire and uniformity were significantly improved with foliar application of MC and N. In conclusion, foliar application of MC and N could be helpful in improving yield and fiber quality of cotton. [ABSTRACT FROM AUTHOR]

Coincidence of heat stress with reproductive stages of cotton accelerates phenology and deteriorates the quality of cotton fiber. A field study was conducted for 2 years to investigate the beneficial role of foliar selenium (Se) application in alleviating the adverse effects of heat stress on cotton growth, development and yield. The experiment was laid out in a randomized complete block design with split arrangement and replicated thrice. Three levels of heat treatment were assigned in the main plots, that is, H0 = No heat stress; H1 = Heat stress imposed at squaring and H2 = Heat stress imposed at flowering. Four levels of foliar spray of Se at 0, 50, 100 and 150 mg/L were applied in each subplot. A remarkable decrease in phenology, quality attributes and seed cotton yield was observed under 'H1' and 'H2', compared to 'H0'. Similar improvements in phenology were recorded with all three doses of Se application, whereas only the highest Se dose 150 mg/L significantly improved seed cotton yield and fiber quality. Conclusively, heat stress was more detrimental at flowering than at the squaring stage for cotton crop in terms of the examined attributes. Application of Se at 150 mg/L is, therefore, recommended to alleviate heat stress, due to its proven beneficial effect on fiber quality and seed yield. [ABSTRACT FROM AUTHOR]

Cotton is severely affected by heat stress in most parts of Pakistan which results in poor quality and low cotton yield. Sixty cotton strains were screened against heat stress on the basis of cellular membrane thermostability, chlorophyll contents, canopy temperature, node number of first fruiting branch, boll weight and seed cotton yield to explore the genetics of variation among genotypes for heat tolerance. Five tolerant and five sensitive parents were sorted out and crossed in Line × Tester mating design during 2018.The F1 crosses along with parents were grown in field under normal and heat stress conditions by using two sowing dates to create heat stress in the field. Sowing during 1st week of April was considered as heat stressed because its peak flowering period was supposed to be coincided with the maximum temperature of May-June; while, sowing during 1st week of June was taken as normal because its peak flowering period coincided with normal temperature of August. Data regarding cell membrane themostability (CMT%), chlorophyll contents, canopy temperature, node number to first fruiting branch, bolls/plant, boll weight, ginning out turn and seed cotton yield under normal as well as heat stressed conditions were collected which showed significant differences among genotypes for all the traits under investigation. Most of the traits showed greater mean square for female × male interaction than female and male individual mean squares and higher dominance variance than additive variance. Broad sense heritability for investigated traits was observed in the order of boll weight (94.56), seed cotton yield (94.51), CMT% (91.88), canopy temperature (90.48), node number to first fruiting branch (75.68) and chlorophyll contents (51.93). FH-458 and PB-76 indicated high general combining ability for most of the traits whereas the cross combination FH-458× FH-326 was described as the best cross showing 56.85% better parent heterosis for seed cotton yield under heat stress conditions. The present study was planned to investigate the genetics of some important physiological and agronomic traits of cotton which is a pre-requisite for the development of high yielding cotton varieties under high temperature stress. [ABSTRACT FROM AUTHOR]

Cotton (Gossypium hirsutum L.) is of prime importance because of its quality fiber and edible oil production. Boron (B) is among essential micronutrients for plant growth; it aids in the transfer of sugars and nutrients from leaves to fruit that are involved directly or indirectly in many plant functions. Cotton growth, yield and quality are strongly affected with boron application. A two-year study was conducted to evaluate the impact of foliar applied B (0, 2, 4, 6, 8 and 10 g of B L−1 of water) on the performance of cotton cultivars (FH-113, MNH-786 and CIM-496). The results indicated that growth, yield and quality traits of cotton were significantly influenced by different levels of foliar applied boron as well as cultivars of cotton. Among cotton cultivars, the yield and quality parameters were superior in cultivar "FH-113." Foliar application of boron at 6 g L−1 of water improved leaf area index and leaf area duration and eventually improved the number of bolls per plant, boll retention percentage, average boll weight, lint yield, ginning out turn, fiber length and uniformity ratio of cotton. Foliar application of B at 6 g per liter of water, showed promising results by improving growth and quality parameters and is recommend to enhance the economical yield production of cotton cultivar "FH-113" with improved quality. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the general combining ability effects of parents and specific combining ability effects of crosses under normal and water deficit condition for various traits related to fibre quality. For this purpose, 50 F1 crosses and their 15 parents was field planted under two different moisture regimes i.e. normal and water deficit condition in the experimental area of Department of Plant Breeding and Genetics, UAF. Analysis of variance under normal and drought condition revealed that genotypes showed highly significant differences for all the traits under both conditions. For most of fibre quality traits, under normal condition, among the lines, the good general combiners were IUB-212 and FH-113 and poor general combiners were VH-295 and NS-121. Among the testers, the good general combiners were IR-3, CIM-443 and S-12 and poor general combiners were MNH-147 and FH-1000. Under the drought condition, among the lines, the good general combiner was IUB-212 and poor general combiners were VH-295 and FH-142. Among the testers, the good general combiner was S-12 and poor general combiners were MNH-147 and IR-3. For most of fibre quality traits the best specific combiner were VH-144 × CIM-443 and AA-802 × S-12 under normal condition while under drought condition the best specific combiner were VH-144 × CIM-443, VH-295 × IR-3, VH-144 × FH-1000 and VH-295 × CIM-443. The variance due to specific combining ability was greater as compared to the general combining ability variance for all the traits indicating the dominant role of non-additive genes under normal and drought condition. The crosses VH-144 × CIM-443 and VH-295 × IR-3 can be used in variety development program for drought prone areas of Pakistan with high specific combining ability for fibre quality traits under drought condition. All fibre quality traits having non-additive gene action suggested usage of this material in the hybrid development programme in cotton. [ABSTRACT FROM AUTHOR]

Heat stress at reproductive stages of cotton is a leading encumbrance to accomplish yield potential. An experiment was conducted to alleviate adversities of terminal heat stress on cotton. Experiment was conducted at University of Agriculture Faisalabad, Pakistan during 2013 and repeated in 2014 using Randomized Complete Block Design (RCBD) with split arrangement. Treatments were comprised of heat stress in main plots, viz., H0 = no heat imposition, H1 = heat imposition at squaring, and H2 = heat imposition at flowering. Selenium was foliar applied in split plot, viz., Se0 = 0, Se50 = 50, Se100 = 100, and Se150 = 150 mg L−1. Cell membrane thermostability, soluble proteins, and total phenolics were reduced significantly under heat stress leading to reduced cotton yield and related components. Maximum membrane thermostability, total phenolics, soluble proteins, opened bolls, boll weight, sympodial branches, and seed cotton yield were recorded with the application 150 mg Se L−1. [ABSTRACT FROM AUTHOR]

Commercial cultivation of Bt cotton produced higher boll load which led to stiff inter-original competition for photosynthates, resulting in early cessation of growth (premature senescence) due to more availability of sink and less sources. To overcome this problem, field experiment was conducted during 2011 and 2012 using five treatments of plant growth manipulation viz. no fruiting branch removal (F1), removal of first fruiting branch (F2), removal of first and second fruiting branch (F3), removal of all squares from first fruiting branch (F4), removal of all squares from first and second fruiting branches (F5), and three potassium (K) application rates viz. 50 kg ha−1(K1), 100 kg ha−1(K2), and 150 kg ha−1(K3). More nodes above white flower were recorded in F5, followed by F3, while minimum were recorded in F1. Among potassium levels, maximum nodes above white flower were recorded in K3followed by K2and K1during both years of study. Plant height recorded at physiological cutout stage or at maturity stage showed that plants gained more height with removal of all squares from first tosecond fruiting branches with higher potassium dose. Leaf K increased with increasing applied potassium and also with square/branch removal. So early removal of squares/fruiting branches along with higher potassium dose helped in delaying canopy senescence in Bt cotton. [ABSTRACT FROM PUBLISHER]

Effect of foliar applied benzoic acid on growth, earliness and nutrients' uptake in heat stressed cotton (Gossypium hirsutum L.) was studied at Department of Agronomy, University of Agriculture, Faisalabad, Pakistan during Kharif 2014. Experiment was laid out in RCBD with split plot arrangement in three replications with net plot size of 3 m × 4.5 m. Treatments included: (a) two levels of heat stress; plots without polythene sheet (control) and plots covered with polythene sheet at square initiation for one week; (b) six benzoic acid levels; viz. control (no spray), control (water spray), benzoic acid spray at 0.25, 0.50, 0.75 and 1.00 mM. The crop was sown on 75 cm apart ridges and plant to plant distance was maintained at 30 cm. All other agronomic practices were kept normal and uniform. The standard procedures were adopted for recording the data on various cotton parameters. The results showed that imposition of heat stress affected cotton phenology and caused all earliness related parameters to occur earlier than control. Heat stress also reduced cotton plants' ability to uptake nutrients (N,P,K Zn and B). However, when crop was applied with benzoic acid, it ameliorated the negative impact of heat stress. Increase in benzoic acid spray concentration increased all above mentioned parameters but upto some extent and then started to decrease. It was concluded that application of 0.75 mM benzoic acid spray improved cotton performance (growth and nutrients' uptake) under both, natural and heat induced environments. Economic analysis also showed that application of 0.75 mM benzoic acid on cotton crop gave maximum net income and benefit cost ratio. [ABSTRACT FROM AUTHOR]

• Heat stress effects on plant water relation and gas exchange components. • High temperature increased the contents of TSP, GR and DPPH. • H 2 O 2 outclassed all others signaling molecules followed by ASA and MLE. • H 2 O 2 enhanced GS, seed index and ginning out turn. • H 2 O 2 improved fiber quality under temperature regimes. The climate change and global warming driven rise in temperature and unpredictable occurrence of heat waves impede cotton plants growth and development. Therefore, environmental friendly thermotolerance strategies are required to sustain optimum crop yield under stressful conditions. Reports on heat stress impacts on plant water relations, gas exchange attributes and physiological parameters, at different reproductive stages of cotton, under controlled and natural conditions are lacking. To investigate the impact of temperature and exogenous application of elicitors, a medium heat tolerant cotton genotype was exposed to control/optimal (30/20 °C), medium (38/24 °C) and high (45/30 °C) temperature stress at squaring, flowering and boll formation stages. Plants were staggered to April (early), May (normal) and June (late) sowing dates under field conditions. Growth regulators, salicylic acid (SA-50 ppm), bio-stimulant moringa leaf extract (MLE-30 times diluted) and signaling molecules, i.e. hydrogen peroxide (H 2 O 2 -30 ppm) and ascorbic acid (ASA-70 ppm), were applied foliarly one day prior to temperature stress treatments. Several physio-biochemical parameters, such as leaf non-enzymatic antioxidant, gas exchange attributes and water relations were measured seven-days after exposure to medium and high temperature regimes. Elevated temperature (45/30 °C) increased the content of total soluble proteins (TSP), activity of glutathione reductase (GR), radical scavenging capacity (DPPH%) and H 2 O 2 generation by 64 %, 26 %, 39 % and 57 %, respectively, compared with optimal temperature plants (control). Similarly, the stomatal conductance (GS), seed index and ginning out turn (GOT%) were reduced by 49 %, 47 % and 44 %, respectively under the high temperature regime compared with control temperature regime. Gas exchange components, water relations, seed index and GOT were also reduced under medium and high temperature regimes. Among the exogenous applications, H 2 O 2 showed profound alleviation of temperature stress, followed by ASA and MLE. Foliar application of H 2 O 2 increased TSP, GR and DPPH% by 1.16 folds, 70 % and 82 % (averaged across during three reproductive stages); while, GS, seed index and GOT were increased by 45 %, 20 %, 22 % under high temperature stress over the control plants of the same thermal regime. In conclusion, oxidative burst and antioxidant activities were increased, whereas stomatal conductance, seed index and GOT were reduced with increasing temperature from 30/20 °C to 38/24 °C and from 38/24 °C to 45/30 °C. On the other hand, H 2 O 2 improved thermotolerance of cotton plants via maintaining cellular redox balance, gas exchange attributes, and further enhanced seed weight and ginning out turn under medium and high temperature regimes. [ABSTRACT FROM AUTHOR]