[Background] Cottonseed oil and protein content as well as germination traits are major indicators of seed quality. However, the responses of these indicators to plant density and mepiquat chloride (MC) are still uncertain. To investigate plant density and MC effects on cottonseed yield and main quality parameters, we conducted a two-year field experiment including four plant densities (1.35, 2.55, 3.75 and 4.95 plants·m− 2) and two doses of MC (0 and 135 g·hm− 2) in Dafeng, Jiangsu Province, in 2013 and 2014.
[Results] The application of MC reduced plant height, fruit branch length and fruiting branch number under different plant densities, resulting in a lower and more compact plant canopy. Cottonseed yield showed a nonlinear increase as plant density increasing and achieved the highest value at 3.75 plants·m− 2, regardless of MC application. No significant interactions were found between plant density and MC for cottonseed yield and quality parameters. The 100-seed weight, cottonseed oil content and vigor index significantly decreased as plant density increased, while these parameters significantly increased with MC applying under different plant densities. Seed vigor index was positively correlated with 100-seed weight and seed oil content across different plant densities and MC treatments.
[Conclusions] Thus, application of MC could realize a win-win situation between cottonseed yield and main quality parameters under various densities; and plant density of 3.75 plants·m− 2combined with 135 g·hm− 2 of MC applying is optimal for high cottonseed yield and quality in this cotton production area.
[Title] Effects of mepiquat chloride on yield and main properties of cottonseed under different plant densities
[Authors] ZHAO Wenqing, YAN Qiang, YANG Hongkun, YANG Xiaoni, WANG Leran, CHEN Binglin, MENG Yali and ZHOU Zhiguo
Journal of Cotton Research. 2019; 2:10
[Background] Low insecticidal protein expression at reproductive organs affect insect resistance in Bt transgenic cotton. In order to enhance flower insecticidal protein expression, the conventional cultivar Sikang1 (S1) and the hybrid cultivar Sikang3 (S3) were used as experimental materials; the applications of selected 5 types of amino acids and 21 types of amino acids were sprayed on the flowers in 2016 and 2017 cotton growing seasons.
[Results] The flower Bt protein contents increased significantly under the two amino acid treatments in both cultivars, the Bt protein concentration increased by 15.2 to 25.8% compared with the control. However, no significant differences were detected between the two treatments of amino acid application. Increased amino acid and soluble protein contents, enhanced GPT, GOT, protease,and peptidase activities were observed under the amino acid application at the flowering stage.
[Conclusions] These results suggest that exterior application of the amino acids treatments could bolster the flower insecticidal protein expression.
[Authors] TAMBEL Leila. I. M., ZHOU Mingyuan, CHEN Yuan, ZHANG Xiang, CHEN Yuan and CHEN Dehua
Journal of Cotton Research. 2019; 2:7
[Background] Cotton fiber maturity is an important property that partially determines the processing and performance of cotton. Due to difficulties of obtaining fiber maturity values accurately from every plant of a genetic population, cotton geneticists often use micronaire (MIC) and/or lint percentage for classifying immature phenotypes from mature fiber phenotypes although they are complex fiber traits. The recent development of an algorithm for determining cotton fiber maturity (MIR) from Fourier transform infrared (FT-IR) spectra explores a novel way to measure fiber maturity efficiently and accurately. However, the algorithm has not been tested with a genetic population consisting of a large number of progeny plants.
[Results] The merits and limits of the MIC- or lint percentage-based phenotyping method were demonstrated by comparing the observed phenotypes with the predicted phenotypes based on their DNA marker genotypes in a genetic population consisting of 708 F2 plants with various fiber maturity. The observed MIC-based fiber phenotypes matched to the predicted phenotypes better than the observed lint percentage-based fiber phenotypes. The lint percentage was obtained from each of F2 plants, whereas the MIC values were unable to be obtained from the entire population since certain F2 plants produced insufficient fiber mass for their measurements. To test the feasibility of cotton fiber infrared maturity (MIR) as a viable phenotyping tool for genetic analyses, we measured FT-IR spectra from the second population composed of 80 F2 plants with various fiber maturities, determined MIR values using the algorithms, and compared them with their genotypes in addition to other fiber phenotypes. The results showed that MIR values were successfully obtained from each of the F2 plants, and the observed MIR-based phenotypes fit well to the predicted phenotypes based on their DNA marker genotypes as well as the observed phenotypes based on a combination of MIC and lint percentage.
[Conclusions] The MIR value obtained from FT-IR spectra of cotton fibers is able to accurately assess fiber maturity of all plants of a population in a quantitative way. The technique provides an option for cotton geneticists to determine fiber maturity rapidly and efficiently.
[Authors] KIM Hee Jin, LIU Yongliang, FANG David D. and DELHOM Christopher D.
Journal of Cotton Research. 2019; 2:8
[Background] Climate change and particularly global warming has emerged as an alarming threat to the crop productivity of field crops and exerted drastic effects on the cropping patterns. Production of cotton has been dropped down to one million bales from 1.4 million bales since 2015 in Pakistan due to the increase in temperature at critical growth stages, i.e., flowering and boll formation. Keeping in view the importance of cotton in the country, this study was conducted to investigate the genetic effects conferring heat tolerance in six populations (P1, P2, F1, F2, BC1 and BC2) developed from cross-1 and cross-2, i.e., VH-282 × FH-142 and DNH-40 × VH-259.
[Results] The results revealed that cross-1 performed better in heat stress as compared with cross-2 for majority of the traits recorded. Boll weight and ginning outturn (GOT) were highly effected under heat stress and had negative correlation with Relative cell injury (RCI). Boll weight, fiber length, fiber strength and fiber fineness were under the control of non-additive gene action, whereas RCI was controlled by additive gene effects. Lower values of genetic advance coupled with higher values of broad sense heritability for these traits except RCI confirmed the role of non-additive genetic effects. Duplicate types of epistasis were recorded for fiber strength in cross-1 in normal condition. However, complementary type of non-allelic interaction was recorded for fiber strength under normal condition, fiber fineness and RCI under heat stressed condition in cross-1. Likewise, boll weight, GOT and fiber length in populations derived from cross-2 in normal condition were also under the influence of complementary type of non-allelic interaction. Significant differences among values of mid parent and better parent heterosis for boll weight in both normal and heat stress condition provided the opportunity to cotton breeders for utilization of this germplasm for improvement of this trait through exploitation of heterosis breeding.
[Conclusion] Cross-1 performed better in heat stress and could be utilized for development of heat tolerant cultivar. RCI was under the influence of additive gene action, so one can rely on this trait for screening of large number of accessions of cotton for heat stress. While other traits were predominantly controlled by non-additive gene action and selection based on these should be delayed in later generations.
[Authors] SALMAN Muhammad, ZIA Zia Ullah, RANA Iqrar Ahmad, MAQSOOD Rana Haroon, AHMAD Saghir, BAKHSH Ali, AZHAR Muhammad Tehseen
Journal of Cotton Research. 2019; 2: 9