本研究于2019-2020年开展了田间试验，研究DPC化控封顶时期和剂量对喷施脱叶催熟剂（50%噻苯•乙烯利悬浮剂，简称TE，2250 g hm^-2）前吐絮率（9月中下旬，药前吐絮率）及TE施用后14天脱叶性状和吐絮率的影响。结果表明，2019年（棉株长势相对正常）晚封顶（T3期，接近生理终止，白花以上节位约为5.0，较当地人工打顶晚7天）与早封顶（T1期，盛花期，较当地人工打顶早7天）和中期封顶（盛花期后7天，与当地人工打顶时间相同）相比，药前吐絮率显著降低5.9%-11.2%；高剂量DPC（270 g hm^-2）封顶与低（90 g hm^-2）、中（180 g hm^-2）剂量DPC封顶相比，药前吐絮率显著降低22.0%。2020年（棉株后期长势偏旺）T3期封顶的药前叶片数虽然少于T1期和T2期，但药后14天的残留叶片数较多，脱叶率较T1和T2期封顶降低23.2%-27.2%；高剂量DPC封顶的药前叶片数与中、低剂量DPC封顶相似，但药后14天的残留叶片数最多，脱叶率较低、中剂量DPC封顶降低15.0%-21.7%。此外，2020年晚封顶主要影响果枝叶片（包括主茎叶）的脱落，而高剂量DPC封顶对果枝叶（包括主茎叶）和营养枝叶片的脱落均有影响。综上，花铃期应用DPC进行化控封顶对棉花熟性和脱叶催熟效果有一定影响，且具体结果与植株生长状态有关。为避免延迟成熟和降低叶片对脱叶催熟剂的敏感性，DPC化控封顶时间不宜过晚，也不宜采用高剂量DPC进行封顶。在黄河流域棉区，建议于盛花期~盛花期后7天左右（当地常年人工打顶时间）应用90-180 g hm^-2 DPC进行化控封顶。

Plant growth regulators (PGRs) are artificially synthesized compounds that have become an important technical guarantee for agricultural production. EDAH (containing 27% ethephon and 3% DA-6) has been proven to inhibit stalk elongation, promote stalk bold and increase mechanical strength and number of vascular bundles. DA-6 could enhance plant photosynthetic capacity and promote cell division and growth. In our study, experiments were performed at summer maize growing season during 2018–2019. The result showed that plant height, ear height and center of gravity height of maize with EDAH+DA-6 treatment were decreased by 10.18, 16.77 and 13.21%, respectively; leaf area and leaf area index also significantly (P<0.001) decreased by 24.11 and 60.15%, respectively; the value of mean tilt angle significantly (P<0.001) increased by 16.72% compared with the control plants, which meant that EDAH+DA-6 could shape more compact plant type. Therefore, lodging rate of maize with EDAH+DA-6 treatment decreased by 6.95% compared with control plants, and the grain yield was increased by 15.51%. In addition, EDAH+DA-6 treatment significantly improved the quality of maize base stalks, such as improving mechanical properties, which increased maize base stalk crushing strength by 22.23%; increased the hemicellulose, cellulose and lignin contents by 6.93, 3.87 and 30.21%, respectively. In conclusion, EDAH+DA-6 treatment could improve summer maize yield by shaping plant morphological characteristics and group photosynthesis.

棉花的脱叶催熟技术在机械收获中必不可少，尤其是在华北平原，由于热量资源不足，导致收获时残留绿叶和未开裂棉铃的比例较大，棉花机械收获受到限制。确定棉花脱叶催熟剂最佳用量，同时最大程度地减少产量和品质的损失至关重要。本文主要研究一种新型脱叶催熟剂-欣噻利（XSL，10%噻苯隆和40%乙烯利的复配剂）对棉花叶片和棉铃的空间分布，以及产量和品质的影响。本试验共设置了四个处理：不同的XSL剂量（1800和2700 mL ha^-1），应用两次（分为两次应用，每次1350 mL ha^-1）和无XSL（清水）对照。该大田试验于2016-2017年在中国河北进行。结果表明：与清水对照相比，所有脱叶催熟处理均未显著影响棉花的产量和纤维品质。两年数据显示，2700 mL ha^-1 XSL一次性喷施的棉花吐絮率比清水对照高13.5％，而其他两个处理均未达到显著水平。三个XSL处理的脱叶率之间没有显著差异，但平均比清水对照高42.2％。年份对XSL应用效果较为显著，表明气候因素会影响XSL的应用。我们得出的结论是，在黄河流域棉区使用XSL的最佳剂量为2700 mL ha^-1，而且无需分成两次应用。我们的结果将促进棉花机械化收获并降低棉花生产的人工成本。

The plant mitochondrial genome displays complex features, particularly in terms of cytoplasmic male sterility (CMS). Therefore, research on the cotton mitochondrial genome may provide important information for analyzing genome evolution and exploring the molecular mechanism of CMS. In this paper, we present a preliminary study on the mitochondrial genome of sea island cotton (Gossypium barbadense) based on positive clones from the bacterial artificial chromosome (BAC) library. Thirty-five primers designed with the conserved sequences of functional genes and exons of mitochondria were used to screen positive clones in the genome library of the sea island cotton variety called Pima 90-53. Ten BAC clones were obtained and verified for further study. A contig was obtained based on six overlapping clones and subsequently laid out primarily on the mitochondrial genome. One BAC clone, clone 6 harbored with the inserter of approximate 115 kb mtDNA sequence, in which more than 10 primers fragments could be amplified, was sequenced and assembled using the Solexa strategy. Fifteen mitochondrial functional genes were revealed in clone 6 by gene annotation. The characteristics of the syntenic gene/exon of the sequences and RNA editing were preliminarily predicted.

Bacillus thuringiensis (Bt) cotton is grown worldwide, including in saline soils, but the effect of salinity on ion fluxes of Bt cotton remains unknown. Responses of two transgenic Bt cotton genotypes (SGK321 and 29317) and their corresponding receptors, Shiyuan 321 (SY321) and Jihe 321 (J321), to 150 mmol L-1 NaCl stress were studied in a growth chamber. The root dry weight of SGK321 and 29317 under NaCl treatment was decreased by 30 and 31%, respectively. However, their corresponding receptor cultivars SY321 and J321 were less affected (19 and 24%, respectively). The root length and surface area of the Bt cultivars were significantly decreased relative to their receptors under salt stress. NaCl treatment significantly increased Cry1Ac mRNA transcript levels in SGK321 and 29317 but did not affect Bt protein content in leaves or roots of either cultivar at 1 and 7 d after NaCl treatment. Fluxes of Na+, K+, and H+ in roots were investigated using the scanning ion-selective electrode technique. Both mean K+ efflux rate and transient K+ efflux of the Bt cultivars increased four-fold compared to their corresponding receptors when exposed to salinity stress. There were no significant differences in Na+ efflux between Bt and non-Bt cottons. Furthermore, the Na+ contents in roots and leaves of all genotypes dramatically increased under salt stress, whereas K+ contents decreased. Our results suggested that Bt cotton cultivars are more sensitive to salt stress than their receptor genotypes.

Timing of harvest is critical for mechanical picking in cotton production, especially in those regions with double cropping system. Appropriate and safe harvest aids will improve timing and facilitate harvest of cotton in the double cropping system. Three defoliants (dimethipin, thidiazuron, and thidiazuron-diuron) and one boll opener (ethephon) were included in this research. They were evaluated for their effects on defoliation, boll opening, seedcotton yield, seed quality, and fiber quality of field grown cotton when used alone or as a mixture in 2009 and 2010. Defoliation and/or boll opening were increased by all three defoliants and ethephon, especially by mixtures of a defoliant and ethephon. First harvest of seedcotton was significantly increased with defoliant-ethephon mixtures. No significant adverse effects were observed on boll weight, lint percentage, seed quality, and fiber properties. It was estimated that tank mixes of ethephon and one of the three defoliants can improve the adjusted gross revenue. Boll opening can be used as an alternative indicator for the adjusted gross revenue, because, it was linearly and positively correlated with the relative adjusted gross revenue and convenient in measurements. Wheat seedling growth was not affected by thidiazuron, whereas its seedling emergence, root dry weight, relative water content, and electrolyte leakage were adversely affected by dimethipin and thidiazurondiuron when concentration was above 340 and 100 g (a.i.) ha-1, respectively. 90% defoliation and 80% boll opening were observed with the high rate of thidiazuron-ethephon mixture, but no adverse effects on winter wheat. The results suggested that tank mixes of ethephon with thidiazuron can be used effectively and safely in the cotton-winter wheat double cropping system to improve yield without adverse effects on seed quality and fiber quality.