Background: Cotton production is adversely effected by drought stress. It is exposed to drought stress at various critical growth stages grown under a water scarcity environment. Roots are the sensors of plants; they detect osmotic stress under drought stress and play an important role in plant drought tolerance mechanisms. The seedling stage is very sensitive to drought stress, and it needed to explore the methods and plant characteristics that contribute to drought tolerance in cotton. Results: Initially, seedlings of 18 genotypes from three Gossypium species: G. hirsutum, G. barbadense, and G. arboreum, were evaluated for various seedling traits under control (NS) and drought stress (DS). Afterward, six genotypes, including two of each species, one tolerant and one susceptible, were identified based on the cumulative drought sensitivity response index (CDSRI). Finally, growth rates (GR) were examined for shoot and root growth parameters under control and DS in experimental hydroponic conditions. A significant variation of drought stress responses was observed across tested genotypes and species. CDSRI allowed here to identify the drought-sensitive and drought-resistant cultivar of each investigated species. Association among root and shoots growth traits disclosed influential effects of enduring the growth under DS. The traits including root length, volume, and root number were the best indicators with significantly higher differential responses in the tolerant genotypes. These root growth traits, coupled with the accumulation of photosynthates and proline, were also the key indicators of the resistance to drought stress. Conclusion: Tolerant genotypes have advanced growth rates and the capacity to cop with drought stress by encouraging characteristics, including root differential growth traits coupled with physiological traits such as chlorophyll and proline contents. Tolerant and elite genotypes of G. hirsutum were more tolerant of drought stress than obsolete genotypes of G. barbadense and G. arboreum. Identified genotypes have a strong genetic basis of drought tolerance, which can be used in cotton breeding programs.

Identifying the ideal plant nature and canopy structure is of great importance for improving photosynthetic production and the potential action of plants. To address this challenge, an investigation was accomplished in 2018 and 2019 at the Institute of Cotton Research (ICR) of the Chinese Academy of Agricultural Science (CAAS), Henan Province, China. Six cotton varieties with diverse maturities and plant canopy structures were used to evaluate the light interception (LI) in cotton, the leaf area index (LAI), the biomass, and the yield throughout the two years of study. The light spatial distribution in the plant canopy was evaluated using a geographic statistical method, following the increasing quantity of radiation intercepted, which was determined using the rules of Simpson. Compared to the cotton plants with a compact structure, varieties with both a loose and tower design captured a comparatively higher amount of light (average 31.3%) and achieved a higher LAI (average 32.4%), eventually achieving a high yield (average 10.1%). Furthermore, the polynomial correlation revealed a positive relationship between the biomass accumulation in the reproductive parts and canopy-accrued light interception (LI), signifying that light interception is critical for the yield development of cotton. Furthermore, when the leaf area index (LAI) was peaked, radiation interception and biomass reached the highest during the boll-forming stage. These findings will provide guidance on the light distribution in cotton cultivars with an ideal plant structure for light capture development, providing an important foundation for researchers to better manage light and canopies.

Leaves are important organs for crop photosynthesis and transpiration, and their morphological characteristics can directly reflect the growth state of plants. Accurate measurement of leaf traits and mining molecular markers are of great significance to the study of cotton growth. Here, we performed a Genome-wide association study on 7 leaf traits in 213 Asian cotton accessions. 32 significant SNPs and 44 genes were identified. A field experiment showed significant difference in leaf hair and leaf area between DPL971 and its natural mutant DPL972. We also compared the leaf transcriptome difference between DPL971 and DPL972, and found a batch of differentially expressed genes and non-coding RNAs (including lncRNAs, microRNAs, and circRNAs). After integrating the GWAS and transcriptome results, we finally selected two coding genes (Ga03G2383 and Ga05G3412) and two microRNAs (hbr-miR156, unconservative_Chr03_contig343_2364) as the candidate for leaf traits. Those findings will provide important genomic resources for cotton leaf improvement breeding.

Combining abilities of cotton varieties were evaluated using a line x tester mating design, twelve hybridswhich developed from 3 testers (male) and 4 lines (females). The experiment was conducted on Randomized Complete Block Design (RCBD) with three replications during 2014. The data were recorded for plant height, sympodial plant-1, bollsplant-1, boll weight and seed cotton yieldplant-1. Chandi-95, NIA-Ufaq and Sadori displayed the highest mean performance and GCA for more or less all the traits, indicating their superiority for inclusion in future breeding programme. The crosses Chandi-95 x BT 802, Sadori x BT A-1, Sohni x BT A-1 and NIA-Ufaq x BT-802 manifested meaning full SCA effects for economic traits, which could be used either for hybrid seed programme or developing superior varieties by applying selection in late segregating generations.

The most crucial factors that reduce developments of plants are the Abiotic stresses. Among abiotic stresses, high temperature is the imperative factor that causes a reduction in crop growth and effect yield. Nowadays, the temperature of Pakistan has raised with approximately 500C, affecting the wheat crop from anthesis stage till maturity and hence, limiting the productivity of wheat. This study focuses on examining the effects of high temperature on wheat genotypes when planted with different sowing date viz. 10th November and 20th December of the year 2017-18, using Randomize Complete Bloch Design (RCBD). Product yield from both sowing dates (early and late) were observed with significant difference in all types of genotypes; for days 75% maturity, 1000-grains yield, grain yield (kg/ha-1), biological yield (kg/ha-1) and in some physiological characters such as area (cm2) of flag leaf, relative percent of water content ( %) and chlorophyll content % at the probability level P≤0.01 and probability level P≤0.05. The early and late planting revealed significant different recorded in RWC (%) and Leaf Area. The late sowing date, the trait RWC (%) shown non-significant result. The maximum reduction recorded in HYT 10 advance line for grain yield kg/ha-1, leaf area and RWC and in HYT 09 more reduction of chlorophyll content was observed. Hence, it was due to delayed planting effect and heat stress.