Path analysis based on genetic association of yield components and insects pest in upland cotton varieties

Gossypium hirsutum L. is also called upland cotton or Mexican cotton. It is the most widely cultivated species of cotton in the whole world. Globally, about 90% of all cotton production comes from the cultivars derived from this species. Some genetic parameters like monopodial branches per plant, sympodial branches per plant, sympodial branch length, bolls per plant, boll weight, sympo-boll distance, Ginning Out Turn%, staple length (rg = 0.9199**), and fiber strength along with seed cotton yield were evaluated for their potential utilization via selection in seed cotton yield improvement. Significant positive genetic correlations were estimated for monopodial branches per plant (rg = 0.9722**), sympodial branches per plant (rg = 0.7098**), sympodial branch length (rg = 0.617**), bolls per plant (rg = 0.8271**), boll weight (rg = 0.8065**), sympo-boll distance (rg = 0.6507**), Ginning Out Turn (GOT)% (rg = 0.7541**), staple length (rg = 0.9199**), and fiber strength (rg = 0.7534**) with seed cotton yield. A path analysis of all the yield traits under study revealed strong positive direct effects of monopodial branch length (1.1556), sympo-boll distance (0.8173) and staple length (0.7633), while plant height exerted a highly strong direct negative effect (-1.2096) on yield. It is concluded that a direct selection based on monopodial branch length and sympo-boll distance, and staple length is effective, whereas, monopodial branch length, and sympodial branch length are good selection indicators via bolls per plant for yield improvement in cotton.

Causation studies for Kapas yield, yield components and lint quality traits in Mexican cotton (Gossypium hirsutum L.)

Cotton is a very important crop that consists of traits with different associationship due to genetic and environmental factors. In order to determine the degree of association between seed cotton yield and important traits, a study was done using an RBD experiment with 30 hybrids. Seed cotton yield, plant height, GOT, number of sympodial braches, boll weight, bolls per plant, span length, fineness and strength data were collected and analysed. The experiment was done with 30 F1 hybrids have delivered through Line x Tester mating configuration utilizing six lines and five testers were planted in a Randomized Block Design (RBD) with two replications at the Department of Cotton, TNAU, Coimbatore. Seed cotton yield per plant was found to have significant positive genotypic connection with boll weight (0.5810), number of bolls per plant (0.3867), plant height (0.422) and ginning percent (0.2182) however altogether and contrarily related with consistency proportion at genotypic level. The phenotypic relationship esteems likewise uncovered that seed cotton yield per plant had highly huge and positive phenotypic connection with number of bolls per plant (0.3470) and boll weight (0.4763). Path coefficients were processed to assess the commitment of individual characters to yield in cotton. The way investigation demonstrated high certain immediate impact of number of bolls per plant (0.4743) and fiber strength (0.6880) on seed cotton yield. Micronaire value displayed high sure circuitous impact on seed cotton yield through range length (0.3393), the outcome showed that number of bolls per plant had a high sure relationship with seed cotton yield and sympodial per plant recorded low certain connection with seed cotton yield. It was therefore concluded that selection of high yielding cotton hybrids could emphasize more on lint yield, boll weights, plant height and bolls per plant for better-performing lines. Gin outturn and fibre strength could be used indirectly to improve seed cotton yield through other traits.

Effect of Zero and Minimum Tillage on Cotton Productivity and Soil Characteristics under Different Nitrogen Application Rates

Long-term conservation tillage and straw incorporation are reported to improve the soil health, growth, and yield traits of crops; however, little is known regarding the optimal nitrogen (N) supply under conservation tillage with straw incorporation. The present study evaluated the effects of conservation tillage practices (ZTsas: zero tillage plus wheat straw on the soil surface as such, and MTsi: minimum tillage plus wheat straw incorporated) and different N application rates (50, 100, 150, and 200 kg ha−1) on the yield and quality traits of cotton and soil characteristics in a five-year field experiment. The results showed that ZTsas produced a higher number of bolls per plant, boll weight, seed cotton yield, 100-seed weight, ginning out-turn (GOT), fiber length, and strength than MTsi. Among different N application rates, the maximum number of bolls per plant, boll weight, seed cotton yield, GOT, 100-seed weight, fiber length, strength, and micronaire were recorded at 150 kg N ha−1. Averaged over the years, tillage × N revealed that ZTsas had a higher boll number plant−1, boll weight, 100-seed weight, GOT, fiber length, and strength with N application at 150 kg ha−1, as compared to other tillage systems. Based on the statistical results, there is no significant difference in total soil N and soil organic matter among different N rates. Further, compared to MTsi, ZTsas recorded higher soil organic matter (SOM, 8%), total soil N (TSN, 29%), water-stable aggregates (WSA, 8%), and mean weight diameter (MWD, 28.5%), particularly when the N application of 150 kg ha−1. The fiber fineness showed that ZTsas had no adverse impact on fiber fineness compared with MTsi. These results indicate that ZTsas with 150 kg N ha−1 may be the optimum and most sustainable approach to improve cotton yield and soil quality in the wheat–cotton system.

Intra-Plant Variability for Heat Tolerance Related Attributes in Upland Cotton

Abiotic stress, particularly heat stress, affects various parts of the cotton plant and ultimately impacts the seed cotton yield. Different portions of a single cotton plant of a cultivar exhibit variable responses to stress during reproductive and vegetative phases. To test this hypothesis, physiological and morphological traits related to heat stress were observed for two flowering positions in 13 genotypes of upland cotton. These genotypes were sown in field conditions in triplicate following a randomized complete block design. Data were collected for pollen germination, pollen viability, cell membrane thermostability, chlorophyll content, boll weight, and boll retention for both the top and bottom branches of each genotype. The collected data were analyzed for the identification of variability within and between genotypes for these two flowering positions. Tukey’s test was applied to estimate the significance of differences between genotypes and positions within each genotype. Results showed that the two positions within the same plant statistically varied from each other. The bottom branches of the genotypes performed significantly better for all traits measured except boll weight. The genotype AA-933 performed best for pollen germination and boll retention, while CYTO-608 exhibited maximum pollen viability in both the bottom and top flower positions compared with other genotypes. Overall, MNH-1016 and CIM-602 showed better cell membrane thermostability and chlorophyll content, respectively. This intra-plant variability can be further exploited in breeding programs to enhance the stress tolerance capabilities of the resulting varieties.

Stability analysis of the new cotton lines

The genotype × environment interaction and the stability of eight cotton lines and the standard variety were studied during 2014-2017. The years of the study appeared to be as different ecological environments. The stability variances (2i and S2i) of Shukla (1972) and YSi index of Kang (1993) were calculated. It was found that the cotton genotypes tested interacted significantly with the environmental (year) conditions in terms of seed cotton yields, boll weigt, fiber length and lint persentage. For an effective selection of these traits, the genotypes had to be tested in different years at diverse environmental conditions and a calculation of the phenotypic stability parameters was necessary for a more precise selection. Based on Sukla’s variance stability parameters the breeding usefull stability was observed for all studed traits. Some lines were stable for more than one traits. Line 553 was found to be stable for the seed cotton yield, boll weight and lint percentage, lines 489 and 457 – for the boll weight and fiber length. These lines appeared to be very suitable for inclusion in crosses. According to Kang’s YSi index the complex breeding value (the average level of trait and stability) was found in: line 553 for the seed coton yield, boll weight, fiber length and lint percentage; line 489 for the boll weight, fiber length and lint percentage; line 535 for the seed coton yield and boll weight; line 449 for the boll weight and fiber length; line 457 for the fiber length. These lines are very suitable for the cotton breeding programs to create genotypes with a high expression and high stability of the traits.

Study on Heterosis for Yield and Yield Contributing Traits in Desi Cotton (Gossypium arboreum L.)

The present investigation entitled “Studies on Heterosis for Yield and Yield Contributing Traits in Desi Cotton (Gossypium arboreum L.) was undertaken with the objective to study the scale of heterosis over mid parent (Average heterosis), better parent (Heterobeltiosis) and standard check (Standard heterosis). The line x tester method of analysis was followed involving four females viz., PA 811, PA 839, PA 808 and PAIG 380 and six males viz. AKA 8, JLA 505, PA 812, AKA 7, PA 08 and Phule Dhanwantry for study of heterosis for various yield and yield contributing characters. The F1’s and theis parents were evaluated in Randomized Block Design with two replications. Observations were recorded on Days to 50 % flowering, Plant height (cm), Number of sympodia, Number of bolls/plant, Boll weight (g), Seed index, Seed cotton yield/plant (g) and Lint index. The magnitude of heterosis was highest for seed cotton yield per plant, which was recorded to the extent of 115.28 % over standard check PKV Suvarna in the cross PAIG 380 x AKA 8 followed by 109.68 % over standard check PKVDH 1.

Combining Ability Analysis for Seed Cotton Yield and Yield Contributing Traits in Desi Cotton (Gossypium arboreum L.) over the Environments

Cotton is one of the most important fiber and cash crop of India and plays a dominant role in the industrial and agricultural economy of the country. Fifty six crosses with fifteen parents and four checks viz., PKVDH 1, PKVSuvarna, NACH 12 and PA 255 were grown in Randomized Block Design with two replications. Pooled over the environments, the highest GCA effect for seed cotton yield plant was showed by line PAIG 346and also exhibited high GCA (in desirable direction) for the traits, sympodia per plant, number of bolls per plant, seed index, lint index and harvest index. Among the testers, highest GCA for seed cotton yield per plant (9.72) was reported in CNA 449.This tester showed significantly desirable GCA for the characters viz. plant height, number of sympodia per plant, number of bolls per plant, boll weight, seed index and harvest index. Pooled over the environments, among the crosses highest SCA for seed cotton yield per plant was reported in PA 740 x Digvijay. It has also exhibited significant SCA in desirable direction for days to 50 % boll bursting, number of sympodia per plant, number of bolls per plant, boll weight, seed index and harvest index. Another cross which ranked second for with high per se and high SCA for seed cotton yield per plant was PAIG 346 x DWDa 1402.It showed significantly desirable SCA for days to 50 % flowering, number of sympodia per plant, number of bolls per plant, seed index, lint index and harvest index.

Enhancement of yield by application of salicylic acid in two cotton varieties grown in semi-arid tropics of Nizamabad

The research experiments conducted on the role of salicylic acid (SA) sprayed in three concentrations viz., 0.5 mM, 1.0 mM and 3.0 mM on the yield in terms of buds/plant, flowers/plant, number of bolls/plant, boll weight, fibre length, number of seeds/plant, 100 seed weight and cotton seed oil contents of two varieties of cotton (Gossypium herbaceum L.) viz., Bt- cotton and non-Bt plants grown in the semi-arid tropics of Nizamabad was studied. Nizamabad district soil is known for its salinity and the black soil which is largely responsible for the drought and saline stresses which hampers plant growth and metabolism. Application of three concentrations of SA stimulated the yield of both Bt-cotton and non-Bt cotton varieties. The Bt-cotton variety showed better performance over non-Bt varieties. SA at 3.0 mM conc. was found most effective in increasing the yield of both cotton varieties of over 1.0mM SA, 0.5mM SA applications as well as untreated controls. The enhancement of yield in terms of buds/plant, flowers/plant, number of bolls/plant, boll weight, fibre length, number of seeds/plant, 100 seed weight and cotton seed oil contents in both cotton varieties is an indicator that SA mitigated the negative effect of the semi-arid conditions of the soils in Nizamabad district.

Genetic Variability, Coefficient of Variance, Heritability and Genetic Advance in American Cotton (Gossypium hirsutum L.)

The present Investigation was carried out to study the genetic variability, coefficient of variance, heritability and genetic advance in American cotton. The material was evaluated in a Randomized Block Design (RBD) with three replications during kharif 2019. In this experiment analysis of variance indicated that significant variation present among the accessions of the upland cotton for all the traits under study. The highest genotypic (GCV) and phenotypic coefficient of variation (PCV) were exhibited by the number of monopodia per plant, number of bolls per plant and boll weight. High heritability with high genetic advance was observed in the boll weight, number of monopodia per plant, number of bolls per plant, seed cotton yield per plant, number of sympodia per plant and lint index. The combination of the high heritability and high genetic advance provide the clear image of the trait in the selection process.