Cotton Genotypes Research Articles

Genotypic variability in cotton's transpiration response under progressive soil drying

IntroductionCrop yields in food and fibre production systems throughout the world are significantly limited by soil water deficits. Identifying water conservation mechanisms within existing genotypes is pivotal in developing varieties with improved performance in water-limited conditions. The objective of this study was to screen Australian germplasm for variability in the transpiration response to progressive soil drying using a glasshouse dry-down experiment. It tests the hypothesis that water conservation traits may provide tolerance to water stress, particularly when combined with other drought stress traits. MethodsThree glasshouse experiments were conducted to identify whether there are differences in the fraction of transpirable soil water (FTSW) threshold values for transpiration decline among six cotton genotypes. We also assessed whether genotype dependent responses to progressive soil drying are evident from leaf-level physiology, by measurement of gas exchange parameters. ResultsSignificant variation in the FTSW threshold for transpiration decline between six genotypes was found, ranging from 0.13 to 0.29. Genotypic variation in the response to soil drying was also observed from leaf level physiology, with reductions in stomatal conductance and photosynthetic rate coinciding with when the FTSW threshold was reached. DiscussionGenotypes that limit transpiration at high FTSW can conserve water earlier in the season to maintain productivity during extended dry periods. Therefore, these genotypes may provide physiological traits that improve productivity in water-limited environments. This research is important as rainfall and water resources for irrigated agriculture are predicted to decline. The development of drought tolerant germplasm for the Australian cotton industry will be beneficial in the projected increasingly frequent limited water environments resulting from a changing climate.

Exploitation of novel drought responsive EST-SSR markers in tetraploid cotton (Gossypium hirsutum L.)

Drought is a major environmental challenge that affects the quality and yield of cotton fibres. The aim of the present study was to develop drought-responsive EST-SSRs from cotton transcriptome data. A total of 1946 functionally annotated EST-SSR markers were developed, with tri-nucleotide SSR repeats being the most abundant (40.7 %), followed by di-nucleotides (18.1 %). Gene Ontology (GO) associated with EST-SSR showed the presence of genes related to drought stress, such as PIP, CDK, LEA, etc. A set of 46 EST-SSRs was validated under In-vitro conditions on fourteen cotton genotypes, and 15 EST-SSRs were found to be polymorphic. The polymorphic EST-SSRs markers amplified a total of 44 loci with 32.6 % polymorphism. Genetic analysis revealed that the markers NAU-G-16, NAU-G-39, NAU-G-117 and NAU-G-142 amplified four unique alleles at 121, 163, 224 and 238 bp, respectively, only in drought-tolerant cotton genotypes. The effectiveness of the markers was demonstrated by their high polymorphism information content (PIC), which ranged from 0.35 to 0.89. The large number of markers, 60 %, had a PIC value of >0.6 and were classified as highly informative. The genetic similarity coefficients between cotton genotypes ranged from 0.409 to 0.89, indicating moderate genetic diversity. The Shannon index ranged from 0.21 to 0.65, while the Nei coefficient ranged from 0.12 to 0.46. Clustering and PCo analysis showed the distribution of genotypes into four main clusters, with drought-tolerant genotypes grouped into a single cluster. These drought-responsive markers are promising for the further development of marker-assisted breeding with the aim of increasing the productivity of cotton under drought-prone conditions.

IMPACT OF DIFFERENT SOWING DATE ON ADVANCED COTTON (Gossypium hirsutum L.) VARIETIES

The purpose of this study was to find out the effect of different sowing dates on advanced cotton (Gossypium hirsutum L.) genotypes. Three different cotton varieties (Sind-1, Th-120, and Star-2) and three sowing dates (May 9, May 16, and May 23) constituted the treatment groups. Current study indicators include plant height (cm), number of branches per plant, number of bolls per plant, ginning percentage, and seed cotton yield kg/ha. The following is a summary of the parameter-wise results. The current study found that the variety Star-2 recorded a maximum plant height of 130.56 cm, while the variety Th-120 recorded a plant height of 122.67 cm. On May 23rd, we recorded a maximum plant height of 136.78 cm, while on May 16th, we recorded a plant height of 132.22 cm. The findings revealed that plant 1 recorded the highest number of sympodial branches at 25.33, with a peak of 29.22 branches per plant on the 23Th-120, while May recorded 25.33 at 23.78, starting from a minimum of Star-2, followed by variety Th-120 at 23.78, and a minimum of 20.00 sympodial branches in variety Sindh-1. However, the 23rd of May recorded a maximum of 29.22 branches per plant. The results revealed that variety Star-2 recorded the maximum (45.11) number of opened bolls per plant, followed by variety Th-120 (41.83). However, the 23rd May sowing date recorded the maximum (45.89) number of bolls per plant, while the 16th May sowing date recorded the lowest (42.22). The 9th May sowing date recorded the minimum of 37.44 bolls per plant. Variety Star-2 recorded the maximum at 38.00, followed by variety Th-2120 at 33.56. However, the crop yielded a maximum of 37.78 GOT% when planted under the 23rd May sowing date. However, the highest seed cotton production was 3429.6 kg ha-1 from variety Star-2, followed by 3066.7 kg ha-1 from variety Th-120. Variety Sindh-1 produced the lowest seed cotton yield: 2577.8 kg ha1. However, variety Sindh-1 produced the highest seed cotton yield (3511.1) on May 23rd and the lowest yield (3133.3 kg ha-1) on May 16th. The 9th of May sowing date yielded the lowest seed cotton yield of 2429.6 kg ha-1. According to the experiment's findings, the yield of seed cotton varied among types, with variety Star-2 and 23rd May planting dates yielding higher yields than other varieties under other sowing dates.

Improvement in photosynthesis under different light intensities is highly linked to domestication stages in cotton.

Domestication has dramatically increased crop size and biomass, reflecting the enhanced accumulation of photosynthates. However, we still lack solid empirical data on the impacts of domestication on photosynthetic rates at different light intensities and on leaf anatomy, and of the relationships of photosynthesis with aboveground biomass. In this study, we measured the photosynthetic rate at three photosynthetic photon flux densities of 2000 (high), 1000 (moderate) and 400 μmol m-2 sec-1 (low light intensity), dark respiration, relative chlorophyll content (SPAD), leaf morphology, and aboveground biomass in 40 wild, 91 semiwild, and 42 domesticated cotton genotypes. The study was replicated for two years (growing years 2018 and 2019). During the first domestication stage (transition from wild to semiwild genotypes), domestication led to higher photosynthetic rates measured under high light intensity, higher SPAD, larger leaf area (LA), and lower leaf mass per unit area (LMA), contributing to greater aboveground biomass accumulation in both study years. During the second domestication stage (transition from semiwild to domesticated genotypes), domestication significantly enhanced photosynthesis under low light intensity and reduced LMA, which were associated with increased aboveground biomass in both study years. In conclusion, photosynthesis improvement at different light intensities has been a gradual domestication phase specific process with the rate of photosynthesis enhanced under high light during the first domestication stage, and under low light during the second domestication stage. We argue that these differences reflect a higher proportion of LA photosynthesizing under low light due to enhanced canopy expansion at the second domestication stage.

Biochemical and morpho-physiological insights revealed low moisture stress adaptation mechanisms in cotton (Gossypium hirsutum L.)

Cotton (Gossypium hirsutum L.) is a multipurpose crop. Abiotic stresses, especially extreme heat and drought, limit crop growth and thus reduce cotton yield by about 50%. In this study, 30 cotton genotypes were tested against low moisture stress in a pot experiment in triplicates along with control under wire house conditions. At the 3–4 leaf stage, different morpho-physiological and biochemical parameters were measured in order to select the low moisture stress-tolerant genotypes. For the selection of the best performing genotypes, Multi-Trait Genotype-Ideotype Distance Index (MGIDI) was used for the ranking of genotypes on the basis of multiple indices. For biochemical traits, 09 (TPC, TF, TSP, MDA, SOD, POD, CAT, APX, and Proline) out of 24 showed significant genotypic effects and were used for MGIDI. Eight genotypes (N-812 N-1296 N-696 N-377 N-121–896 N-T86, and N-3496) were observed to be best performing than others at 25% selection pressure (SI = 25%). For morpho-physiological traits, 14 out of 15 showed significant genotypic effects and used for MGIDI. Ten genotypes (N-1237 N-812 N-1296 N-696 N-9078 N-377 N-512 N-121 N-375, and N-896) were observed to be best performing at 35% selection pressure (SI = 35%). Six genotypes, i.e. N-812–1296 N-696 N-377 N-121, and N-896 were found common in both MGIDI analysis. In conclusion, three genotypes, i.e. N-696, N-896, and N-T86 proved to be most resilient to low moisture stress. Develop protocols, identified genotypes and markers that can be used for development of climate-smart cotton genotypes.

Genetic Dissection of Flowering and Plant Architectural Traits to Develop Early Maturing Compact Upland Cotton Genotypes for High-Density Planting

Genetic Dissection of Flowering and Plant Architectural Traits to Develop Early Maturing Compact Upland Cotton Genotypes for High-Density Planting

INTERRELATION OF YIELD AND ITS COMPONENTS IN COTTON (Gossypium hirsutum L.) GENOTYPES

Cotton is regarded as a profitable crop that gives people fiber and shelter. Research focuses on how yield, its components, and related attributes work together to enhance cotton. During the Kharif season of 2022, the present study was completed, implementing a randomized complete block design with ten genotypes and three replications. The study took place at the Nuclear Institute of Agriculture (NIA), located in Tandojam. This work aimed to examine the correlation and regression between upland cotton genotypes and heritability estimates for traits associated with yield. The outcomes showed that all of the parameters in the mean square of the ANOVA were significant. In contrast to the remaining genotypes, genotype FH-142 displayed the most favorable performance; it had the tallest plants, more sympodial branches, more bolls per plant, an improved seed index, and the longest staple length. The genotype CRIS-342 came in second, exhibiting good plant height, sympodial branches, a good number of bolls per plant, a ginning outturn, and the highest boll weight among the other genotypes. The findings of the correlation and regression indicated that the number of bolls per plant-1 had a highly significant and positive relationship with monopodial branches plant-1 (r = 0.73*) and (b = 2.45) and that the number of bolls per plant had a strong relationship with seed cotton yield plant-1 (r = 0.83**) and (b = 3.29). Staple length and seed cotton yield plant-1 had a negative correlation (-0.77*) with regression (b = -4.58). The highest heritability estimates in the broad sense are for monopodial branch plants (84.61), ginning outturn% (97.03), bolls plant-1 (93.96), plant height (90.70), staple length (79.31), and seed index (71.42). However, the boll's weight showed a low heritability (23.71). Further breeding programs can utilize genotype FH-142 to increase the number of sympodial branches, increase the number of boll plants, and improve the staple length. Genotype CRIS-342 can be utilized for medium-stature plant height, boll weight, and better ginning outturn. However, genotype NIA-BT-40 can be utilized for short-strategy plants with the highest ginning output.

Resistance and genetic divergence of wild cotton genotypes under attack by sucking pests

Resistance and genetic divergence of wild cotton genotypes under attack by sucking pests

Transcriptome Analysis and Identification of Genes Associated with Cotton Seed Size.

Cotton seeds, as the main by-product of cotton, are not only an important raw material for edible oil and feed but also a source of biofuel. The quality of cotton seeds directly affects cotton planting and is closely related to the yield and fiber quality. However, the molecular mechanism governing cotton seed size remains largely unexplored. This study investigates the regulatory mechanisms of cotton seed size by focusing on two cotton genotypes, N10 and N12, which exhibit notable phenotypic variations across multiple environments. Developing seeds were sampled at various stages (5, 20, 30, and 35 DPA) and subjected to RNA-seq. Temporal pattern clustering and WGCNA on differentially expressed genes identified 413 candidate genes, including these related to sugar metabolism that were significantly enriched in transcriptional regulation. A genetic transformation experiment indicated that the overexpression of the GhUXS5 gene encoding UDP-glucuronate decarboxylase 5 significantly increased seed size, suggesting an important role of GhUXS5 in regulating cotton seed size. This discovery provides crucial insights into the molecular mechanisms controlling cotton seed size, helping to unravel the complex regulatory network and offering new strategies and targets for cotton breeding to enhance the economic value of cotton seeds and overall cotton yield.

MORPHOLOGICAL AND PHYSIOLOGICAL RESPONSES OF DIFFERENT COTTON GENOTYPES UNDER NORMAL AND SALT STRESS CONDITIONS

Salinity is a major abiotic stress that badly affects the growth and production of cotton worldwide. This scenario is not different in the case of Pakistan. This research was conducted to examine the effects of different salinity levels on the morpho-physiological characters of six cotton genotypes i.e. shoot and root length, fresh shoot and root weight, photosynthesis rate, and transpiration rate. A pot experiment was arranged with three salinity treatments of NaCl i.e. control (0 dS/m), T1 (4.5 dS/m), and T2 (8.5 dS/m) with three replications of each treatment. Highly significant decreases in shoot length, fresh shoot weight, fresh root weight, photosynthesis rate, and transpiration rate were observed with increasing salinity levels across all genotypes. The genotype MNH-786 showed the highest reduction in all morpho-physiological characters, indicating it was highly sensitive to salinity stress. On the other hand, FH-87 and FH-142 maintained relative performance for all discussed morpho-physiological traits under both moderate and high salinity, demonstrating that these are relatively more tolerant. These findings provided valuable insights into the salinity tolerance of cotton genotypes and highlighted the potential of FH-87 and FH-142 for cultivation in saline-prone areas and for use in breeding programs to improve salinity tolerance in cotton.

Integrative analyses of long and short-read RNA sequencing reveal the spliced isoform regulatory network of seedling growth dynamics in upland cotton.

The polyploid genome of cotton has significantly increased the transcript complexity. Recent advances in full-length transcript sequencing are now widely used to characterize the complete landscape of transcriptional events. Such studies in cotton can help us to explore the genetic mechanisms of the cotton seedling growth. Through long-read single-molecule RNA sequencing, this study compared the transcriptomes of three yield contrasting genotypes of upland cotton. Our analysis identified different numbers of spliced isoforms from 31,166, 28,716, and 28,713 genes in SJ48, Z98, and DT8 cotton genotypes, respectively, most of which were novel compared to previous cotton reference transcriptomes, and showed significant differences in the number of exon structures and coding sequence length due to intron retention. Quantification of isoform expression revealed significant differences in expression in the root and leaf of each genotype. An array of key isoform target genes showed protein kinase or phosphorylation functions, and their protein interaction network contained most of the circadian oscillator proteins. Spliced isoforms from the GIGANTEA (GI) protien were differentially regulated in each genotype and might be expected to regulate translational activities, including the sequence and function of target proteins. In addition, these spliced isoforms generate diurnal expression profiles in cotton leaves, which may alter the transcriptional regulatory network of seedling growth. Silencing of the novel spliced GI isoform Gh_A02G0645_N17 significantly affected biomass traits, contributed to variable growth, and increased transcription of the early flowering pathway gene ELF in cotton. Our high-throughput hybrid sequencing results will be useful to dissect functional differences among spliced isoforms in the polyploid cotton genome.

GhJUB1_3-At positively regulate drought and salt stress tolerance under control of GhHB7, GhRAP2-3 and GhRAV1 in Cotton.

Climate change severely affects crop production. Cotton is one of the primary fiber crops in the world and its production is susceptible to various environmental stresses, especially drought and salinity. Development of stress tolerant genotypes is the only way to escape from these environmental constraints. We identified sixteen homologs of the Arabidopsis JUB1 gene in cotton. Expression of GhJUB1_3-At was significantly induced in the temporal expression analysis of GhJUB1 genes in the roots of drought tolerant (H177) and susceptible (S9612) cotton genotypes under drought. The silencing of the GhJUB1_3-At gene alone and together with its paralogue GhJUB1_3-Dt reduced the drought tolerance in cotton plants. The transgenic lines exhibited tolerance to the drought and salt stress as compared to the wildtype (WT). The chlorophyll and relative water contents of wildtype decreased under drought as compared to the transgenic lines. The transgenic lines showed decreased H2O2 and increased proline levels under drought and salt stress, as compared to the WT, indicating that the transgenic lines have drought and salt stress tolerance. The expression analysis of the transgenic lines and WT revealed that GAI was upregulated in the transgenic lines in normal conditions as compared to the WT. Under drought and salt treatment, RAB18 and RD29A were strongly upregulated in the transgenic lines as compared to the WT. Conclusively, GhJUB1_3-At is not an auto activator and it is regulated by the crosstalk of GhHB7, GhRAP2-3 and GhRAV1. GhRAV1, a negative regulator of abiotic stress tolerance and positive regulator of leaf senescence, suppresses the expression of GhJUB1_3-At under severe circumstances leading to plant death.

INFESTATION OF DIFFERENT INSECT PESTS ON NOVEL COTTON CULTIVARS AND THEIR IMPACTS ON COTTON FIBER QUALITY PARAMETERS

Pakistan is the 5th largest producer of cotton in the world. Exports of cotton and textile products have a share of around 60 percent in overall exports of the country. A field experiment was conducted to evaluate the different fiber quality parameters in relation to different insect pest populations. The introduction of this new types of cultivars may satisfy the needs of farmers for better quality and quantity, laborers who harvest crops, and other investors, including those in the cotton sector. A field research was carried out at the Cotton Research Station, Faisalabad, Pakistan, during the year 2023 cotton cultivars (VH-447, FH-1133, BH-228, SLH-94, MNH-S GOLD, BH-227, FH-1214, MNH-1095, VH-442, MNH-1090, RH-BAGHO BAHAR, MNH-1050, and MNH-TP) were evaluated for resistance to sucking pests such as whitefly (Bemisia tabaci); jassid (Amrasca biguttula biguttula); and thrips (Thrips tabaci) as well as bollworms such as pink bollworm (Pectinophora gossypiella); spotted bollworm (Earias insulana; E. vitelli); and American bollworm (Helicoverpa armigera). There were notable variations across the genotypes in terms of the population of sucking and bollworm insect pest infestation, which lowers cotton production and negatively affects fiber quality. FH-1133 showed the lowest average populations of thrips (1.00/leaf), jassid (0.27/leaf), and whiteflies (2.00/leaf), indicating the highest resistance. The average population (9.84%) of pink bollworm larvae in residual boll. The virus percentage on different cotton genotypes recorded after 30, 60, 90, and 120 days was 0.00, 9.00, 14.00, and 19.00%, respectively. The cultivar FH-1133 was observed to be good for all other genotypes of cotton due to its yield (2372.50 kg/acre), and it had the following lint quality attributes: GOT (46.50%), staple length (28.50 mm), fiber fineness (4.70 µg/inch), and fiber strength (33.20 g/tex).

TRACING THE DIVERSITY OF CULTIVATED TRANSGENIC COTTON IN PAKISTAN BY SSR BASED DNA FINGERPRINTING

The introduction of transgenic Bacillus thuringiensis (Bt) cotton is one of the success stories of applying biotechnology in agriculture. It also decreased the use of insecticides and the production cost as an environmental and economic benefit, respectively. The use of selective genotypes as a parental material for Bt cotton breeding has resulted in the multiplication of limited germplasm. The main objective of the study was to find out the genetic diversity of cultivated Bt cotton genotypes by fingerprinting. Twenty-two SSR markers were used to analyze the genetic differences in Bt cotton genotypes, collected from two different sources i.e., research institutes and open market. Results showed that the Polymorphism information content (PIC) value ranged from zero to 0.673. A UPGMA based dendrogram divided all the genotypes into four main clusters. Eighty-six percent similarity was observed between VH-282 and AS-01 while the lowest similarity of 45% was found between IUB-222 and FH-167.This diversity of newly introduced transgenic genotypes will help to detect the diverse lines to be used in future for broadening the genetic base of Bt cotton in Pakistan. Another observation was that a genotype, FH-114 oBtained from two sources was clustered in two different clades. This showed the presence of name variants for a particular genotype depicting adulteration of seed available in seed market which need to be addressed. Though the adoption of Bt cotton was rapid, but the economic impact of this adoption was not significant in Pakistan as compared to other developing countries. The identified problem might be one of the reasons, limiting the benefits of this technology to be harvested out of it.

Integrating genetic assortment and molecular insights for climate-resilient breeding to unravel drought tolerance in cotton

This study addresses the challenges posed by rainfall variability, leading to water deficits during critical stages of crop growth, resulting in a drastic reduction of cotton yield. In a comprehensive evaluation, thirty cotton genotypes, including five Gossypium arboreum (wild) and twenty-five Gossypium hirsutum (cultivated), were grown under rainfed and irrigated conditions. Drought tolerance indices (DTI) were evaluated, categorizing genotypes based on their resilience. Further, in-vitro screening at the seedling stage (20 days) under PEG-induced drought identified tolerant genotypes exhibiting elevated levels of free proline (19.07±5.31 mg.g−100fr.wt.), amino acids (34.59±6.51 mg.g−100fr.wt.), soluble proteins (13.73±2.65 mg.g−1fr.wt.), and glycine betaine (10.95±3.62 mg.g−100fr.wt.), in their leaves, positively correlating (p<0.001) with relative water content (87.70±3.45 %). Molecular analysis using drought-specific simple sequence repeats (SSR) markers revealed significant genetic variability in a cotton genotypes, with lower observed and higher expected heterozygosity. F statistics exposed a higher level of gene flow corresponding to low differentiation among populations. Among the genotypes group, wild GAM-67 and cultivated Deviraj emerged as the most potent, exhibiting the higher DTI and diverse gene pools. Study exhibited higher total gene diversity in drought-tolerant wild GAM-67 (0.8501) and greater expected heterozygosity (0.626) and gene flow (0.6731) in cultivated Deviraj, underlining their robust genetic adaptability to drought conditions. The integrated approach of field evaluations, in-vitro screening, and molecular analyses explained substantial genetic diversity, with the identification of promising genotypes displaying higher drought tolerance indices, elevated levels of stress-related biochemical osmolytes, and pronounced genetic adaptability, thereby contributing to the advancement of breeding initiatives for enhanced drought resilience in cotton.

Impact of elevated temperatures on the genetic and morpho-physiological traits of cotton genotypes cultivation

Impact of elevated temperatures on the genetic and morpho-physiological traits of cotton genotypes cultivation

Selection of productive early maturing cotton genotypes with improved fibre quality parameters

The purpose of this article was to study productivity and fibre quality of different cotton genotypes under conditions of Turkestan region of Kazakhstan to determine the most promising genotypes for commercial cultivation. Four genotypes were selected: Tashkent-6, Maktaral-5027, Namangan-1 and Bukhara-8. The study included analysis of such parameters as germination and sprouting time, plant height, flowering and maturity time, yield, number of bolls and fibre quality characteristics. The results showed that Tashkent-6 and Maktaral-5027 had the best parameters: yield 3.8 t/ha and 3.5 t/ha, flowering time 55 days and maturity 120 days, plant height 120 cm and 115 cm, number of bolls 45 and 42. The fibre quality of these genotypes was also high: length 32 mm and 31 mm, tensile strength 30 g/tex and 29 g/tex, fineness 2.5 dtex and 2.6 dtex. Namangan-1 and Bukhara-8 genotypes showed moderate results: yield 3.2 t/ha and 3.0 t/ha, flowering time 60 days and ripening time 130 days, plant height 110 cm and 105 cm, number of bolls 40 and 38, fibre length 30 mm and 29 mm, tensile strength 28 g/tex and 27 g/tex, fineness 2.8 dtex and 2.9 dtex. Statistical analysis confirmed the significance of differences between genotypes. The results of the study confirmed high productivity and fibre quality of genotypes Tashkent-6 and Maktaral-5027, which makes them promising for commercial cultivation in Kazakhstan, while genotypes Namangan-1 and Bukhara-8 also have potential for certain agronomic conditions

SALINITY, VERTICILLIUM WILT TOLERANCE AND GENETIC DIVERSITY ANALYSIS OF UPLAND COTTON GENOTYPES

Cotton is one of the most economically important crops. Screening and selection salt-tolerant cotton genotypes using DNA molecular markers not only introduces tolerant cultivars valuable for hybridization and breeding programs, but also identifies DNA regions implicated in the salinity tolerance mechanism. Screening and selection of cotton genotypes resistant to salinity stress and Verticillium wilt disease using DNA molecular markers not only introduces tolerant cultivars valuable for hybridization and breeding programs, but also identifies DNA regions implicated in the tolerance mechanism. The lowest Disease Severity Index was recorded in AP-317 (0.37) and Tashkent-2 (0.32) varieties. A total of 63 bands were generated based on 12 ISSR primers, 50 of which were polymorphic. The highest PIC value was recorded for UBC841 (0.466). AP-317 of Azerbaijan origin and Kirqizistan-174 of Kyrgyzstan origin were the most distant (0.358) genotypes and at the same time showed high resistance to Verticillium wilt. The obtained results showed that ISSR markers were an effective tool for determining genetic variation and identification of cotton cultivars.

Effects of Phosphorus-Mediated Alleviation of Salt Stress on Cotton Genotypes: Biochemical Responses and Growth Adaptations

Salinity stress can significantly impact productivity in agricultural area with limited water re-sources. Our study focused on how plants under salt stress respond to phosphorus availability in terms of growth and biochemical reactions in cotton genotypes. Two cotton genotypes with different P efficiencies (SK39 and JM21) were used in a hydroponic experiment with 300 mM NaCl and three P treatments (10, 20, and 30 mM). Salinity stress decreases root growth, shoot growth, biomass production, and chlorophyll content, according to the experimental findings. In treated plants, it also increased the levels of oxidative stress. However, this effect was alleviated by phosphorus therapy, which controlled the production of proline, total soluble sugars, and hydrogen peroxide (H2O2). Interestingly, salt-sensitive JM21 responded to phosphorus supplementation more favorably than salt-tolerant SK39. Our research emphasizes the critical role that phosphorus especially P20 plays increasing the salinity stress sensitivity of cotton plants and offers insightful in-formation on the mechanisms underlying the role of phosphorus in reducing salinity stress effects. This study also revealed interspecific variability in cotton genotypes and characteristics, primarily represented by attributes related to cotton growth and morphological indicators such as dry matter biomass.

Impact of Different Plant Densities and Fertilizer Levels on Yield Attributes, Yield and Fibre Quality Characters of Bt Cotton in HDPS

Adopting a high-density planting system in cotton cultivation has resulted in increased yields compared to traditional methods. Despite the clear benefits, farmers face various challenges throughout the cultivation process, from sowing to harvesting. However, selecting appropriate plant spacings, fertilizer levels and implementing tailored cultivation techniques can significantly enhance productivity. A field experiment was conducted at Siddapur research farm, Regional Agricultural Research Station, Warangal, Telangana, India during kharif 2023 to investigate the “Impact of different plant densities and fertilizer levels on yield attributes, yield and fibre quality characters of cotton in high density planting system (HDPS)”. The experiment was laid out in randomized block design (factorial) and replicated thrice, consisting of 12 treatment combinations comprising of three plant spacings S1: 80 x 20 cm (62,500 plants ha-1), S2: 90 x 15 cm (74,074 plants ha-1), S3: 90 x 60 cm in factor I and four fertilizer levels (F1: 100%RDF, F2: 125%RDF, F3: 100%RDF + Microbial consortia, F4: Control) in factor II. Both the factors significantly influenced the number of bolls per plant, number of bolls m-2 and seed cotton yield per hectare. The results revealed that higher no. of bolls plant-1 were recorded in 90 x 60 cm (18,518 plants ha-1) however, higher no. of bolls m-2, seed cotton yield (2233 kgha-1) obtained from higher plant density (74,074 plants ha-1) with the spacing 90 x 15 cm. Boll weight was not significantly influenced by varied plant spacings and fertilizer levels. Among the different levels of fertilizer, 125%RDF recorded highest no. of bolls per plant, no. of bolls m-2 and seed cotton yield (2362 kgha-1). Fibre quality characters viz., Upper half mean length(mm), micronaire(µginch-1), tenacity(gtex-1) and uniformity index (%) were not significantly influenced by both plant spacings and fertilizer levels as they are primarily governed by genetic makeup of cotton genotypes. For optimum seed cotton yield, cotton should be sown at closer spacing 90 x 15 cm and the application of 125%RDF was economically feasible in high density planting system.