与其他器官相比，Bt转基因棉棉铃中杀虫蛋白含量最低。该文研究了盛花期喷施氨基酸对棉铃Bt蛋白浓度和产量形成的影响、相关的蛋白质合成和碳水化合物转化机制。2017-2018年棉花生长季节，以2个陆地棉品种（杂交种泗抗3号和常规种泗抗1号）为试验材料，设置三个处理（即CK，对照；LA1，组成Bt蛋白的5种主要氨基酸；LA2，21种氨基酸）于盛花期喷施棉铃。结果表明，棉铃Bt蛋白浓度提高5.2%-16.4%，籽棉产量提高5.5%-11.3%，2个氨基酸处理间没有差异。此外，由于氨基酸的应用，棉铃游离氨基酸和可溶性蛋白含量、谷氨酸丙酮酸转氨酶（GPT）和谷氨酸草酰乙酸转氨酶（GOT）活性、葡萄糖和果糖含量、可溶性酸性转化酶（SAI）活性均有所增加。同时发现，棉铃Bt蛋白含量、铃数增长量和铃重与碳氮代谢密切相关，Bt蛋白含量与游离氨基酸含量、可溶性蛋白含量呈显著以上水平线性正相关。花后15-25天，铃数增长量与GPT活性、GOT活性呈显著以上水平线性正相关。花后55-65日铃重与SAI活性呈显著以上水平线性正相关。这些结果表明，氨基酸的应用促进了棉铃蛋白质合成和碳水化合物转化，从而提高了棉铃Bt蛋白浓度和皮棉产量。

2013-2016年于扬州大学试验田，本试验对短季棉品种中棉所50（CRRI50）进行了密度（12.0、13.5和15.0株﹒m^-2）和缩节胺剂量（180、270和360 g ha^-1）的组合处理。结果表明，在13.5株﹒m^-2和270g﹒ha^-1 缩节胺处理下，单位面积铃数最多，棉铃日增量最高，90%以上的棉铃均出现在离地面高45-80cm范围内。综上所述，麦后直播棉种植模式下，适宜的缩节胺剂量配合高种植密度可促进集中成铃，使中、上冠层棉铃分布较多，并且不减产，从而克服目前移栽棉种植模式下用工多的问题。

在棉花生产中，种植密度是用来控制棉铃分布、成铃情况和产量的常用栽培方法。2015年和2016年在大田条件下，研究了5种种植密度（PD1-PD5:15000；30000；45000；60000和75000株·ha^-1）对两个Bt棉品种泗抗1号（常规品种）和泗抗3号（杂交品种）Bt杀虫蛋白含量的影响。单株铃数、铃重、棉铃体积均随密度的增加而减少。当种植密度从15000株/hm2增加到75000株/hm2时，棉子中Bt杀虫蛋白含量增加，2015年花后40天SK-1和SK-3中Bt杀虫蛋白含量分别增加了66.5%和53.4%，2016年SK-1和SK-3分别提高了36.8%和38.6%。氮代谢结果分析表明，随着密度的增加，可溶性蛋白含量、谷氨酸丙酮酸转氨酶（GPT）和谷氨酸草酰乙酸转氨酶（GOT）活性增加，游离氨基酸含量、蛋白酶和肽酶活性降低。花后20天数据分析表明，棉子Bt杀虫蛋白含量与可溶性蛋白水平呈显著正相关，2015年在SK-1和SK-3中的相关系数分别为0.825**和0.926**，2016年在SK-1和SK-3中的相关系数分别为0.955**和0.965**。相比之下，棉子Bt杀虫蛋白水平与游离氨基酸含量呈显著负相关，2015年在SK-1和SK-3中的相关系数分别为-0.983**和-0.974**，2016年在SK-1和SK-3中的相关系数分别为-0.996**和-0.986**。为进一步证实Bt杀虫蛋白含量与氮代谢的关系，分析发现Bt杀虫蛋白含量与GPT和GOT活性呈正相关，与蛋白酶和肽酶活性呈负相关。综上所述，高种植密度增加了棉子Bt杀虫蛋白含量，该增加与单株铃数、铃重和铃体积的减少密切相关。此外，在高种植密度下，氮代谢的变化也有助于Bt杀虫蛋白含量的增加。

在转Bt基因抗虫棉（Bt棉）所有器官中，棉铃中杀虫蛋白含量最低。这也影响了Bt棉高产的获得。本文主要探讨了喷施不同浓度氮素（尿素）对Bt棉棉子中杀虫蛋白含量和籽棉产量的影响及其相关的生理机制。2017-2018年以泗抗3号（杂交种）和泗抗1号（常规种）为材料，在棉铃形成期，喷施不同浓度尿素。2017年设置0%、2%、4%、6%、8%、10% 等6个浓度；2018年设置0%、1%、3%、5%、7%、9%等6个浓度。尿素浓度对Bt棉棉子中杀虫蛋白含量和最终籽棉产量均有明显影响，其中喷施5%-6%尿素处理可显著提高供试品种棉子中杀虫蛋白含量且籽棉产量最高。进一步分析表明，喷施5%-6%尿素处理下，泗抗3号和泗抗1号棉铃中游离氨基酸和可溶性蛋白含量、谷氨酸丙酮酸转氨酶(GPT)和谷氨酸草酰乙酸转氨酶(GOT)活性均较高，但肽酶和蛋白酶活性却显著降低。相关性分析表明，游离氨基酸含量、GPT活性与棉子中杀虫蛋白含量呈显著线性正相关关系。此外，喷施5%-6%尿素后，供试品种田间棉铃虫数量及蛀铃率均显著降低，这也为最终高产的获得奠定了基础。喷施外源氮素可显著影响Bt棉棉子中杀虫蛋白含量，进而提高其对棉铃虫的抗性。其中喷施5%-6%尿素效果最为明显。

为了阐明减氮施肥对抗虫棉棉蕾中Bt杀虫蛋白含量的影响，在2015-2016棉花生长季，以常规种泗抗1号（SK-1）和杂交种泗抗3号（SK-3）为试验材料，分别进行了0、75、150、225、300 kg/公顷的施氮量处理。在不同施氮量处理下，随着施氮量从常规施氮量（300kg/公顷）降低到0 kg/公顷，单株蕾数、棉蕾体积和棉蕾干重均呈下降趋势，同时棉蕾Bt杀虫蛋白含量也相应下降。氮代谢分析结果表明，减氮条件下可溶性蛋白含量、GPT和GOT活性降低，游离氨基酸含量、肽酶和蛋白酶活性升高。相关性分析结果表明，缺氮条件下Bt蛋白含量的降低与氮代谢生理变化相关。综上所述，减氮条件下，棉蕾生长和棉蕾中Bt杀虫蛋白含量均呈下降趋势，因此在蕾期适当的施氮量在促进棉蕾生长的同时也可提高棉花抗虫性。在人间游历 爱是最壮观的迁徙。

The cotton direct seeding after wheat (rape) harvested is under trial and would be the future direction at the Yangtze River Valley region of China.  The objective of this study was to quantify the effects of branch and stem architecture on cotton yield and identify the optimal cotton architecture to compensate the yield loss due to the reduction of individual production capacity under high planting density in the direst seeding after wheat harvested cropping system.  The characteristics of the stem and branch architecture and the relationships between architecture of the stem and branch with yield formation were studied on eight short season cotton cultivars during 2015 and 2016 cotton growth seasons.  Based on the two years results, three cultivars with different architectures of stem and branch were selected to investigate the effect of mepiquat chloride (MC) application on the architecture of the stem and branch, boll retention, and the yield in 2017.  Significant differences were observed on plant height, all fruiting nodes to branches ratio (NBR) in the cotton plant, and the curvature of the fruiting branch (CFB) among the studied cultivars.  There were three types of stem and fruiting branch structures: Zhong425 with stable and suitable plant height and NBR (about 90 cm and 2.5, respectively), high CFB (more than 10.0), and high boll retention speed and seed cotton yield; Siyang 822 with excessive plant height and NBR, low CFB, and low boll retention speed and seed cotton yield; and other studied cultivars with unstable structure of stem and branch, boll retention speed, and seed cotton yield across years.  And MC application could promote the appropriate plant height and NBR and high CFB and thus resulted in high boll retention speed and the yield.  The results suggested that the suitable plant height and NBR (about 90 cm and 2.5 respectively), and high CFB (more than 10.0), which was related to both genotype and cultural practice, could promote the higher boll retention speed and seed cotton yield.

This study was conducted to investigate the effects of alternating high temperature on Cry1Ac protein content on Bt cotton cultivars Sikang 1 (SK-1, a conventional cultivar) and Sikang 3 (SK-3, a hybrid cultivar). In 2011 and 2012, cotton plants were subjected to high temperature treatments ranging from 32 to 40°C in climate chambers to investigate the effects of high temperature on boll shell insecticidal protein expression. The experiments showed that significant decline of the boll shell insecticidal protein was detected at temperatures higher than 38°C after 24 h. Based on the results, the cotton plants were treated with the threshold temperature of 38°C from 6:00 a.m. to 6:00 p.m. followed by a normal temperature of 27°C during the remaining night hours (DH/NN) in 2012 and 2013. These treatments were conducted at peak boll growth stage for both cultivars in study periods of 0, 4, 7, and 10 d. Temperature treatment of 32°C from 6:00 a.m. to 6:00 p.m. and 27°C in the remaining hours was set as control. The results showed that, compared with the control, after the DH/NN stress treatment applied for 7 d, the boll shell Cry1Ac protein content level was significantly decreased by 19.1 and 17.5% for SK-1 and by 15.3 and 13.7% for SK-3 in 2012 and 2013, respectively. Further analysis of nitrogen metabolic physiology under DH/NN showed that the soluble protein content and the glutamic pyruvic transaminase (GPT) activities decreased slightly after 4 d, and then decreased sharply after 7 d. The free amino acid content and the protease content increased sharply after 7 d. The changes in SK-1 were greater than those in SK-3. These results suggest that under DH/NN stress, boll shell Cry1Ac protein content decline was delayed. Reduced protein synthesis and increased protein degradation in the boll shell decreased protein content, including Bt protein, which may reduce resistance to the cotton bollworm.

Cotton cultivars with brown (Xiangcaimian 2), green (Wanmian 39) and white (Sumian 9) fiber were investigated to study fiber developmental characteristics of natural-colored cotton and the effect of hormones on fiber quality at different stages after anthesis. Fiber lengths of both natural-colored cottons were lower than the white-fibered control, with brown-fibered cotton longer than green. Fiber strength, micronaire and maturation of natural-colored cotton were also lower than the control. The shorter fiber of the green cultivar was due to slower growth during 10 to 30 days post-anthesis (DPA). Likewise, the lower fiber strength, micronaire and maturation of natured-colored cotton were also due to slower growth during this pivotal stage. Indole-3-acetic acid (IAA) content at 10 DPA, and abscisic acid (ABA) content at 30 to 40 DPA were lower in the fibers of the natural-colored than that of the white-fibered cotton. After applying 20 mg L^–1 gibberellic acid (GA3), the IAA content at 20 DPA in the brown and green-fibered cottons increased by 51.07 and 64.33%, fiber ABA content increased by 38.96 and 24.40%, and fiber length increased by 8.13 and 13.96%, respectively. Fiber strength, micronaire and maturation were also enhanced at boll opening stage. Those results suggest that the level of endogenous hormones affect fiber quality. Application of external hormones can increase hormone content in natural-colored cotton fiber, improving its quality.

Cotton (Gossypium hirsutum L.) plants produce more ethylene when subjected to abiotic stresses, such as high temperatures and drought, which result in premature leaf senescence, reduced photosynthetic efficiency, and thus decreased yield. This study was conducted to test the hypothesis that the ethylene-inhibiting compound 1-methylcyclopropene (1-MCP) treatment of cotton plants can delay leaf senescence under high temperature, drought, and the aging process in controlled environmental conditions. Potted cotton plants were exposed to 1-MCP treatment at the early square stage of development. The protective effect of 1-MCP against membrane damage was found on older compared to younger leaves, indicating 1-MCP could lower the stress level caused by aging. Application of 1-MCP resulted in reduction of lipid peroxidation, membrane leakage, soluble sugar content, and increased chlorophyll content, in contrast to the untreated plants under heat stress, suggesting that 1-MCP treatment of cotton plants may also have the potential to reduce the effect of heat stress in terms of delayed senescence. Application of 1-MCP caused reductions of lipid peroxidation, membrane leakage, and soluble sugar content, together with increases in water use efficiency (WUE), water potential, chlorophyll content, and fluorescence quantum efficiency, compared to the untreated plants under drought, suggesting that 1-MCP treatment of cotton plants may also have the ability to reduce the level of stress under drought conditions. In conclusion, 1-MCP treatment of cotton should have the potential to delay senescence under heat and drought stress, and the aging process. Additionally, 1-MCP is more effective under stress than under non-stress conditions.

Higher boll worm survival rates were detected after high temperature presented during square period in Bt cotton. The objective of this study was to investigate the effects of high temperature level on the Bt efficacy of two different types of Bt cotton cultivars at squaring stage. During the 2011 to 2013 cotton growth seasons, high temperature treatments ranged from 34 to 44°C in climate chambers, and field experiments under high temperature weather with various temperature levels were conducted to investigate the effects of the high temperature level on square Bt protein concentration and nitrogen metabolism. The climate chamber experiments showed that the square insecticidal protein contents reduced after 24 h elevated temperature treatments for both cultivars, whereas significant declines of the square insecticidal protein contents were detected at temperature >38°C, and only slightly numerical reductions were observed when temperature below 38°C. Similar high temperature responses were also observed at the two field experimental sites in 2013. Correspondingly, high temperature below 38°C seems have little effect on the square amino acid concentrations, soluble protein contents, glutamic- pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) activities as well as protease and peptidase activities; however, when the temperature was above 38°C, reduced soluble protein contents, enhanced amino acid concentrations, decreased GPT and GOT activities, bolstered protease and peptidase activities in square were detected. In general, the higher the temperature is (>38°C), the larger the changes for the above compound contents and key enzymes activities of the square protein cycle. The findings indicated that the unstable insect resistance of the square was related to high temperature level during square stage.

Expression of insecticidal protein for transgenic Bacillus thuringiensis (Bt) cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbon nitrogen ratio (C/N) and insecticidal efficacy of two Bt cotton cultivars. C/N ratio and Bt protein content were both measured at peak square period and peak boll period respectively under 5-7 d high temperature and different nitrogen fertilizer rates on the Yangzhou University Farm and the Ludong Cotton Farm, China. All plants were grown in field. The results showed that the C/N ratio enhanced slightly and the Bt protein content remained stable at peak square period, but significant increases for the C/N ratio and decreases markedly for the leaf Bt protein concentration were detected at the peak boll period. The similar patterns at the two growth periods were found for the leaf C/N ratio and Bt protein content by different N fertilizer treatments. When nitrogen rate was from 0 to 600 kg ha-1, the C/N ratio was reduced by 0.017 and 0.006 for Sikang 1 and Sikang 3 at peak square period, compared to the 1.350 to 1.143 reduction for Sikang 1 and Sikang 3 at peak boll period, respectively. Correspondingly, the leaf Bt protein contents were bolstered by 2.6-11.8 and 26.9-36.9% at the two different growth periods, respectively. The results suggested that enhanced C/N ratio by high temperature and nitrogen application may result in the reduction of insectiocidal efficacy in Bt cotton, especially in peak boll period.