施氮量与播种期对棉花产量和品质及棉铃对位叶光合产物的影响

【目的】本研究旨在揭示施氮量调控不同播种期棉铃对位叶光合产物形成与运转的生理机制,以期为棉花的合理氮肥运筹提供理论依据。【方法】试验于2005和2007年在中国农业科学院棉花研究所(河南安阳,黄河流域黄淮棉区)进行,以科棉1号和美棉33B品种为材料,设置大田不同播种期(4月25日和5月25日)和不同施氮量[低氮N 0 kg/hm2(N0)、适氮N 240 kg/hm2(N240)、高氮N 480 kg/hm2(N480)]处理,研究施氮量对不同播种期棉花产量和品质及棉铃对位叶光合产物的影响。【结果】1)4月25日播种条件下,随施氮量的增加棉铃对位叶中蔗糖含量先升高后降低,淀粉含量增加;随播种期的推迟,N240、N480处理下的棉铃对位叶蔗糖和淀粉含量差异不明显,但均显著高于N0处理;花后24~45 d,棉铃对位叶中蔗糖含量与叶氮浓度呈显著正相关,且相关系数随花后天数的增加而降低;花后17~24 d,蔗糖转化量与叶氮浓度呈显著负相关,至花后31~52 d,反而呈显著正相关(P0.01)。表明棉铃对位叶中适宜叶氮浓度有利于碳水化合物的累积。2)4月25日播种条件下,N0、N480处理对棉花单株铃数、铃重和皮棉产量影响为负效应,对纤维长度和麦克隆值影响较小;晚播低温条件下,N480处理的棉花铃重、皮棉产量、纤维比强度均有所提高,麦克隆值得以优化。因此,施氮量与播种期对纤维比强度和麦克隆值的影响存在补偿效应,晚播棉花增加施氮量可减小因低温而造成的纤维比强度降低的幅度,优化麦克隆值。【结论】本试验条件下,播种期(温度)和施氮量对棉铃对位叶光合产物含量、棉花产量和品质存在互作效应,其主导因素是播种期(温度),施氮量对其有补偿效应。随播种期的推迟,施氮量N 240 kg/hm2时棉花单铃重、产量及纤维品质降低的主要原因是晚播低温使棉铃对位叶中的光合产物(蔗糖和淀粉含量)增加,抑制了光合产物向棉铃及纤维的运输。晚播低温条件下,适量追施氮肥可调节棉铃对位叶中的氮浓度并提高光合产物再利用的能力,促进棉花单铃的形成,降低棉纤维比强度的下降幅度,优化麦克隆值。     

氮素对花铃期干旱再复水后棉花纤维比强度形成的影响

2005—2006在南京农业大学卫岗试验站进行盆栽试验,设置正常灌水和棉花花铃期土壤短期干旱处理,每个处理再设置3个氮素水平（N 0、240、480 kg/hm2）,研究氮素对花铃期短期干旱再复水后棉花纤维比强度形成的影响。结果表明,干旱处理结束时,干旱处理棉花的纤维可溶性蛋白含量较正常灌水处理显著降低,而内源保护酶,即:超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性升高,丙二醛（MDA）含量增加;纤维加厚发育相关酶,即:蔗糖合成酶、磷酸蔗糖合成酶、β-1,3-葡聚糖酶和IAA氧化酶的活性均显著降低。在复水后第10d,干旱处理棉花的纤维内源保护酶活性迅速恢复到正常灌水处理水平,MDA含量降低,但纤维发育相关酶的活性仍低于相应正常灌水处理,纤维比强度亦显著低于正常灌水处理。在棉花的纤维加厚发育期土壤短期干旱再复水条件下,以N 240 kg/hm2最有利于形成高强纤维。干旱期间该处理棉花的纤维内源保护酶活性高,细胞膜脂过氧化程度最低,其纤维加厚发育相关酶活性均最高;复水后该处理的纤维内源保护酶活性迅速恢复,MDA含量最低,棉花的纤维加厚发育相关酶活性仍处于最高值,有利于纤维素的合成与累积,最终纤维比强度亦最大。施氮不足（N 0 kg/hm2）或过量施氮（N 480 kg/hm2）均表现出相反的趋势。     

CottonXL模型模拟研究延迟型低温冷害对棉花纤维品质的影响

为了明确不同程度、不同时段低温对棉花纤维品质的影响,该研究利用棉花延迟型低温冷害指标和灾情资料,筛选出1961－2018年间不同程度延迟型低温冷害的典型年份,在实现棉花功能结构模型CottonXL模型本地化应用的基础上,利用CottonXL模型模拟不同程度冷害对纤维品质的影响。结果表明：CottonXL模型能够较准确地模拟延迟型冷害对棉花纤维品质的影响,不同热量条件下纤维长度、纤维比强度、马克隆值模拟结果与实测值间的RMSE分别为0.7 mm、0.9 cN/tex、0.1。冷害对棉花纤维马克隆值影响最大、纤维比强度次之,对纤维长度影响最小。随冷害程度的加重纤维长度较长、纤维比强度较大且马克隆值适中的棉铃数量显著减少（P＜0.01）,纤维品质整体下降。发生轻度、中度和重度冷害时,纤维长度分别下降0.8、1.4和1.5 mm,纤维比强度分别降低3.9、4.5和5.1 cN/tex,马克隆值分别降低1.0、1.2和1.4。同等程度延迟型低温冷害情况下,夏秋季低温冷害对纤维品质的影响大于春季低温冷害。轻度夏秋季型低温冷害对纤维品质的影响较中度春季型低温冷害更大。     

施氮量对棉铃干物质和氮累积及分配的影响

以高品质棉（科棉1号）和常规棉（美棉33B）品种为材料,2005年在江苏徐州（11711E, 3415N）、2007年在河南安阳（11413E, 3604N）设置施氮量（低氮N 0 kg/hm2,适氮N 240 kg/hm2,高氮N 480 kg/hm2）试验,研究施氮量对棉铃干物质、氮累积分配和棉铃（纤维、棉子）品质的影响。结果表明:施氮可改变棉铃各部分干物质和氮素的累积特征,进而影响棉铃重和棉铃品质。在本试验N 240 kg/hm2水平下,单铃棉子和纤维的干物质累积量最大,棉铃各部分（铃壳、纤维、棉子）氮含量适中、氮累积量最高,最终铃重最大,棉纤维和棉子品质最优;在不施氮（N 0 kg/hm2）时,棉铃干物质和氮快速累积期开始较早、累积速率较低,最终干物质和氮累积量均较低,铃重最低,棉纤维和棉子品质最差。在N 480 kg/hm2水平下,棉铃各部分（铃壳、纤维、棉子）的氮含量和累积量提高,且在成熟棉铃中棉纤维干物质的分配系数下降,棉子中的氮分配系数提高,最终棉子中蛋白质含量上升,铃重和棉纤维比强度、棉子油分含量均降低。综上所述,施氮量过低影响棉铃干物质和氮素的累积,而施氮量过高则主要影响棉铃干物质和氮素在铃壳、棉子和纤维间的分配,二者均导致最终的铃重降低、棉纤维和棉子品质变劣。     

施氮量对不同开花期棉（Gossypium hirsutum L.）铃纤维细度和成熟度形成的影响

为兼顾试验的重复性和生态区域性,选用高品质棉（科棉1号）和常规棉（美棉33B）品种为材料,于2005年分别在江苏南京（118o50E, 32o02N,长江流域下游棉区）和江苏徐州（11711E, 3415N,黄河流域黄淮棉区）设置施氮量（低氮:N 0 kg/hm2;适氮:N 240 kg/hm2;高氮:N 480 kg/hm2）试验,研究施氮量对不同开花期棉铃纤维细度、成熟度和马克隆值形成的影响。结果表明:（1）施氮量显著影响棉纤维细度、成熟度和马克隆值的形成过程,但三者在不同开花期对氮素水平的响应不同,施氮量与开花期对棉纤维细度、成熟度和马克隆值的形成存在互作效应。8月10日前开花的棉铃,铃期［花后0～50 d （DPA）］日均温在23.3 oC以上,纤维细度、马克隆值以N 0 kg/hm2施氮量下最大,棉纤维马克隆值与纤维细度的相关性较大;8月25日开花的棉铃（铃期日均温在20.8～23.3 oC之间）,纤维成熟度、马克隆值以N 240 kg/hm2施氮量下最大;9月10日开花棉铃（铃期日均温低于20.8 oC）,纤维细度、成熟度和马克隆值均以N 480 kg/hm2最大,棉纤维马克隆值与纤维成熟度的相关性增强。（2）影响不同开花期间纤维细度、成熟度和马克隆值的主要因素是铃期日均温,最终纤维细度、成熟度和马克隆值在不同施氮量之间的变异与不同开花期（铃期日均温不同）间的变异比较,前者显著小于后者。综上,因开花期不同而形成的铃期日均温是决定细度、成熟度和马克隆值的最重要因素,施氮量可通过对位叶叶氮浓度NA影响棉纤维细度、成熟度和马克隆值的形成过程,增加施氮量可减小上述指标在不同开花期间的差异。     

氮素对棉花果枝、果节及蕾铃发生与脱落影响的模拟

为了探明氮素对棉花形态指标与蕾铃脱落的影响,该研究通过设置施氮量试验,以累积温光效应为驱动变量,以花铃期棉株下部果枝对位叶平均氮浓度为氮营养指标,模拟氮营养水平对棉花主要形态指标与蕾铃脱落率的动态影响。结果表明,棉花下部果枝对位叶氮浓度随花后天数呈幂函数下降趋势,其平均氮浓度出现的花后天数占花铃期总天数的比值较稳定,可作为植株N营养状态指标;棉株的果枝数、果节数、成铃数随累积温光效应（cumulative thermal and solar radiative effectiveness,TSE）呈logistic曲线变化,棉蕾数和幼铃数随TSE呈二次曲线变化,且各拟合方程中的参数响应N处理而变化,与花铃期棉株下部果枝对位叶平均氮浓度呈二次函数关系。利用独立的试验资料检验,在不同施氮水平下,棉株果枝数、果节数、棉蕾数、幼铃数、成铃数和脱落率的RMSE分别平均为1.1个/株、2.7个/株、2.4个/株、1.6个/株、1.4个/株和3.5%,模拟值与观测值具有较好的吻合度;在不同种植密度条件下,模拟值与观测值也具有较好的吻合度。本研究可为棉田施肥管理提供参考。     

改进作物水分亏缺指数用于东北地区春玉米干旱灾变监测

为了明确不同程度、不同时段低温对棉花纤维品质的影响,该研究利用棉花延迟型低温冷害指标和灾情资料,筛选出1961－2017年间不同程度延迟型低温冷害的典型年份,在实现棉花功能结构模型CottonXL模型本地化应用的基础上,利用CottonXL模型模拟不同程度冷害对纤维品质的影响。结果表明：CottonXL模型能够较准确地模拟延迟型冷害对棉花纤维品质的影响,不同热量条件下纤维长度、纤维比强度、马克隆值模拟结果与实测值间的RMSE分别为0.7 mm、0.9 cN/tex、0.1。冷害对棉花纤维马克隆值影响最大、纤维比强度次之,对纤维长度影响最小。随冷害程度的加重纤维长度较长、纤维比强度较大且马克隆值适中的棉铃数量显著减少（P＜0.01）,纤维品质整体下降。发生轻度、中度和重度冷害时,纤维长度分别下降0.8、1.4和1.5 mm,纤维比强度分别降低3.9、4.5和5.1 cN/tex,马克隆值分别降低1.0、1.2和1.4。同等程度延迟型低温冷害情况下,夏秋季低温冷害对纤维品质的影响大于春季低温冷害。轻度夏秋季型低温冷害对纤维品质的影响较中度春季型低温冷害更大。     

外施吲哚乙酸对棉铃蔗糖代谢及产量性状的影响

为探究外施吲哚乙酸(IAA)对棉铃蔗糖代谢及棉铃产量性状的调控机制,以陆地棉(Gossypium hirsutum L.)品系A201为材料,用0.1 mg·L^-1 IAA溶液连续处理开花前1 d至开花后2 d的棉铃,以去离子水处理为对照,研究IAA处理对棉铃胚珠外表皮纤维细胞突起、蔗糖代谢及棉铃产量性状的影响。结果表明,IAA处理能够显著提高棉铃单铃重,促进棉铃开花当日纤维细胞启动的密度。与对照相比,IAA处理可增强开花后30 d种胚磷酸蔗糖合成酶(SPS)活性,导致蔗糖浓度升高,为种胚大分子物质合成提供更多的底物;并提高了开花后30~40 d种胚和开花后20~30 d种皮蔗糖合成酶(SS)的活性,增加了种胚和种皮的淀粉浓度,促进了棉花种子库物质合成。另外,IAA处理棉铃可以促进棉铃种胚和种皮蔗糖代谢关键酶的活性,提高其碳水化合物特别是淀粉的浓度,有利于棉铃种子的发育,这可能是导致单铃重提高的重要原因。本研究结果对于利用IAA提高棉花产量具有指导意义。     

钾素营养对不同部位棉铃纤维品质性状的影响

在大田试验条件下,研究了钾素营养对上、下部位棉铃纤维品质性状的影响。试验选用2个品种,4个施钾量（K2O 0,60,180和300 kg/hm2）。结果表明:施钾提高了上、下部棉铃的纤维长度,增大了最终纤维麦克隆值,且随施钾量的增加,增幅呈加大趋势,但施钾对纤维长度达最大值的时间无影响;施钾提高了上、下部位棉铃纤维的最终零隔距比强度和3.2 mm隔距比强度,但在上、下部位棉铃间表现存在一定差异,下部棉铃纤维的最终零隔距比强度和3.2 mm隔距比强度均随施钾量的增加呈先增加后降低趋势,上部铃则随施钾量增加一直呈增大趋势;施钾还提高了上、下部棉铃纤维的最终成熟度,而且其增幅随施钾量的增加而增大,当施钾量为300 kg/hm2时,可显著增加上、下部位棉铃纤维的最终成熟度。     

香蕉纤维酶解脱胶工艺及脱胶纤维性能

香蕉纤维的开发利用是香蕉茎秆资源综合利用的有效突破口。该研究以中国主栽品种巴西蕉香蕉茎秆纤维为研究对象,采用俐迪链霉菌对其进行生物脱胶,研究其产酶和脱胶的条件并对脱胶后纤维的结构和理化性质进行分析。研究结果表明:俐迪链霉菌在果胶和半纤维素筛选培养基中观察到明显的水解圈,具有水解果胶和半纤维素的能力;以残胶率和果胶酶活性为指标,筛选出产酶和脱胶的条件为:pH值5.0、NH4NO34 g/L、麸皮10 g、接种量9 mL,在此条件下菌体产酶活力为75μg/(mL·min),香蕉纤维残胶率4.80%,纤维得率为59.48%;扫描电镜(scanning electron microscope,SEM)结果显示脱胶后纤维的直径和表面结构发生了改变;脱胶后纤维的强力从345.37 cN降至273.37 cN,纤维的细度由18.55 tex增加至8.91 tex;纤维中的纤维素含量增加,半纤维素、木质素和果胶等非纤维素成分明显减少,致使脱胶后的纤维素热稳定性和结晶度都明显增加,这一结果与SEM、X射线衍射(X-ray diffraction,XRD)和傅立叶红外光谱(Fourier transform infrared spectroscopy,FTIR)分析结果一致;表明该菌株在香蕉纤维脱胶方面具有一定的应用前景。     

Response of cotton fiber quality to the carbohydrates in the leaf subtending the cotton boll

This study investigated the effect of nitrogen (N) fertilization on leaf and boll N and carbohydrate concentrations in the development of fiber quality. A two‐year field study was conducted with two cotton (Gossypium hirsutum L.) cultivars, Kemian 1 (average fiber strength 35 cN tex^–1) and NuCOTN 33B (average fiber strength 32 cN tex^–1) at five (2008) and four (2009) N levels. The relationship between leaf and boll N and carbohydrate concentrations was assessed from measurements of N, carbohydrates, chlorophyll (based on SPAD readings), and free amino acids in the leaf subtending the boll, together with fiber carbohydrates and development of fiber quality. Results indicate that leaf N concentration more accurately reflected boll N status than the concentration of chlorophyll or free amino acids. Leaf sucrose and nonstructural carbohydrate had a quadratic relation with leaf N concentration (p < 1%). The optimal leaf N concentration ranged from 3.0% to 2.4%. During 24–38 d post‐anthesis (DPA), fiber sucrose was positively related to leaf sucrose and nonstructural carbohydrate (p < 5%), but was not correlated with leaf starch or total soluble carbohydrates. Fiber strength was positively correlated with fiber sucrose before 38 DPA, and it appeared to be more easily influenced by the fiber sucrose concentration than fiber length, fineness, or maturity. These results suggest that 24–38 DPA is a crucial period for fiber development which might be significantly influenced by physiological and ecological factors. In addition, sucrose or nonstructural carbohydrates in the subtending leaf could be used as a monitoring index to evaluate sucrose levels in the developing fiber, and also for predicting the final fiber strength.     

氮素营养水平对棉花不同部位叶片衰老的生理效应

通过3个氮素(N)水平(低氮0.kg/hm2、中氮189.50.kg/hm2、高氮395.0.kg/hm2)处理,研究棉花主茎功能叶和不同部位果枝叶衰老过程中的生理生化变化特征。以转基因抗虫棉33B为材料,采用随机区组设计,研究棉花生育期内不同施氮水平下棉花叶面积指数和叶片(主茎功能叶和果枝叶)生理指标(叶绿素含量、可溶性蛋白质含量和丙二醛含量)的差异,分析氮素影响不同部位叶片衰老的效应。结果表明:1)在本试验条件下,盛铃末期为各指标变化的转折点,表明这个时期是叶片生理功能衰老的起始期;2)氮素营养缺乏会引起整体叶片的叶绿素、可溶性蛋白质含量大幅度下降,丙二醛含量升高,加速了叶片的衰老进程;3)当氮素过多时,会加速下部叶片的衰老,上部果枝叶对氮素的缺乏最敏感,因此,施入适量的氮肥,可获得延缓整株叶片衰老的效果。     

Establishing indicator leaf and its threshold values for need based nitrogen management using chlorophyll meter and leaf color chart in Bt cotton

Over application of fertilizer N to cotton is not only a potential threat to environment but also leads to increased costs of cultivation. The study aimed to establish the indicator leaf and its critical greenness for in-season management of fertilizer nitrogen (N) in Bt cotton using chlorophyll (SPAD) meter and leaf color chart (LCC). The response of three varieties and N treatments viz. 0, 30, 60, 90,120, 150 and 180?kg N ha^?1 applied in two splits {(50% at thinning and 50% at first flowering) and three splits (50% at thinning, 25% at first flowering and 25% at boll formation)} was studied through split plot design. SPAD values and LCC scores of first, second, third and fourth fully opened leaves from the top of the main stem was recorded at first flowering and boll formation. The physiological efficiency and harvest index was highest for 90?Kg N ha^?1 applied in two splits. Beyond 120?kg N ha^?1, the N use efficiency parameters were higher for the N treatments applied in three split compared to the respective two split N treatments. The fourth leaf from the top in terms of SPAD values and LCC scores correlated best with N concentration compared to other leaves at all growth stages. The calculated critical SPAD values for the fourth leaf were 45 and 41 at first flowering and boll formation, respectively. Critical score of fourth leaf was 4.1 and 4, respectively at first flowering and boll formation, respectively. It is suggested that color of the fourth leaf from the top of Bt cotton can well indicate N supply from the soil and can help in need based N management.     

Studies on post‐reddening changes in amino acid content leaves of hirsutum cotton and its control with chemicals

The aspartic acid,tyrosine and serine contents of leaves were found reduced in prematurely reddened leaves of hirsutum cotton (Gossypium hirsutum) as compared to healthy green leaves. Amino acids other than those listed above were higher in the affected red leaves. Amino acids threonine and proline increased 63.7 and 2.3 fold over green leaves respectively. Chemical sprays not only maintained the levels of various amino acids at par with green leaf but tended to increase the concentration above the levels obtained in normally found green leaf. However, threonine level was dropped in treated leaves as compared to partly affected red leaf and chemical sprays significantly reduced the leaf reddening when it was sprayed before flowering. It can be suggested that the leaf reddening can possibly be arrested by monitoring threonine content in leaves of hirsutum cotton ov. L‐147.     

Zinc Fertilization Impact on Irrigated Cotton Grown in an Aridisol: Growth,Productivity, Fiber Quality,and Oil Quality

Zinc (Zn) deficiency is widespread in calcareous soils. Therefore, we conducted a 2-year field experiment to investigate the impact of graded Zn levels on growth, yield, and fiber and oil quality of cotton (Gossypium hirsutum L., cv. CIM-473) grown in a calcareous Aridisol having 0.54 mg diethylenetriaminepentaacetic acid (DTPA)-extractable Zn kg^?1 soil. Zinc use increased boll bearing, boll weight, seed index, and seed cotton yield (P ≤ 0.05). Maximum yield increase was 15%, with 7.5 kg Zn ha^?1; however, greater Zn levels depressed yield. Leaf chlorophyll, membrane permeability, seed protein, and oil content and quality improved (P ≤ 0.05), and fiber quality remained unaffected with Zn use. Critical Zn concentration in cotton leaves was 36 mg kg^?1. Positive relationships of leaf Zn concentration were observed with boll weight, protein content, total unsaturated fatty acids, and fiber characteristics. Thus, Zn fertilization of low-Zn Aridisols is suggested for improving cotton productivity and seed quality.