棉(Gossypium hirsutum L.)纤维发育相关酶和纤维比强度对棉铃对位叶氮浓度变化的响应研究

于2008～2009年在长江流域下游棉区,选用纤维比强度差异明显的德夏棉1号（平均比强度26.2 cN/tex）、科棉1号（平均比强度35 cN/tex）和美棉33B（平均比强度32 cN/tex）为试验材料,设置不同施氮量以形成不同的棉铃对位叶氮浓度,研究了棉铃对位叶氮浓度对纤维发育过程中关键酶（蔗糖酶、蔗糖合成酶、磷酸蔗糖合成酶、-1, 3-葡聚糖酶）活性及纤维比强度形成的影响。结果表明,棉铃对位叶氮浓度随施氮量的增加而上升,随花后天数的变化符合幂函数方程YN＝t-［YN:棉铃对位叶氮浓度（%）;t:花后天数（d）;、为参数］。在花后同一时期,纤维发育关键酶活性和纤维比强度均随棉铃对位叶氮浓度的上升呈先升后降的趋势,可用抛物线方程Y=ax2+bx+c拟合［Y:酶活性或纤维比强度（cN/tex）;x:叶片氮浓度（%）;a、b、c为参数］。表明在纤维发育过程中,棉铃对位叶氮浓度显著影响纤维中相关酶活性和纤维比强度的形成,各指标所对应的最佳棉铃对位叶氮浓度差异较小;因此,通过调节对位叶氮浓度可调控相关酶活性达到最优以及棉花高强纤维的形成。在本试验条件下,中部棉纤维发育所需的最佳对位叶氮浓度动态变化方程分别为:NDexiamian1=7.2841t-0.2771(R2=0.9860＊＊);NKemian1=7.1807t-0.2989(R2=0.9879＊＊);NNuCOTN33B=7.1467t-0.2819(R2=0.9755＊＊)。     

Foliar feeding of boron improves the productivity of cotton cultivars with enhanced boll retention percentage

Abstract

Cotton (Gossypium hirsutum L.) is of prime importance because of its quality fiber and edible oil production. Boron (B) is among essential micronutrients for plant growth; it aids in the transfer of sugars and nutrients from leaves to fruit that are involved directly or indirectly in many plant functions. Cotton growth, yield and quality are strongly affected with boron application. A two-year study was conducted to evaluate the impact of foliar applied B (0, 2, 4, 6, 8 and 10?g of B L^?1 of water) on the performance of cotton cultivars (FH-113, MNH-786 and CIM-496). The results indicated that growth, yield and quality traits of cotton were significantly influenced by different levels of foliar applied boron as well as cultivars of cotton. Among cotton cultivars, the yield and quality parameters were superior in cultivar “FH-113.” Foliar application of boron at 6?g L^?1 of water improved leaf area index and leaf area duration and eventually improved the number of bolls per plant, boll retention percentage, average boll weight, lint yield, ginning out turn, fiber length and uniformity ratio of cotton. Foliar application of B at 6?g per liter of water, showed promising results by improving growth and quality parameters and is recommend to enhance the economical yield production of cotton cultivar “FH-113” with improved quality.     

短期高温胁迫对海岛棉不同部位果枝产量形成的影响

高温是影响棉花产量的重要环境因子,研究盛花期短期高温胁迫对海岛棉不同部位果枝产量及产量构成因素的影响,有助于为海岛棉选育耐热稳产性品种、制定丰产抗逆栽培技术提供理论方法。以‘新海43号’和‘新海49号’为材料,于盛花期在田间搭设增温棚,设置不同增温持续时间[0 d （CK）、3 d （H3）、6 d （H6）、9 d （H9）]模拟短期高温胁迫对海岛棉干物质积累、叶片净光合速率、蕾铃脱落率、产量及产量构成因素的影响。结果表明：盛花期短期高温胁迫,导致‘新海43号’和‘新海49号’中部果枝蕾铃脱落率显著增加,棉株总干物质积累量下降。在花后30~50 d,各增温处理棉铃的干物质量与对照相比显著降低;而花后40~50 d,两品种H6、H9处理茎、叶干物质量与对照相比显著升高。随生育进程的推进,‘新海43号’和‘新海49号’在H3、H6、H9处理下棉铃最大干物质量比对照分别降低8.9%、29.3%、36.3%和11.8%、28.1%、42.6%;棉铃日均积累量分别下降10.9%、32.8%、42.2%和12.8%、30.3%、45.9%;而达到快速积累期终止时期所需的时间分别增加5 d、8 d、14 d和1 d、5 d、10 d。在增温处理期间,两品种主茎叶P_n随增温持续时间的延长呈大幅下降趋势;增温结束后,各处理叶片P_n的衰减速度不同,在生殖生长后期（花后40 d） H3、H6、H9处理下叶片P_n均高于对照,表现为H9 > H6 > H3 > CK。短期高温胁迫导致两品种单株结铃数、单铃重和衣分显著降低,其中单株结铃数变异系数（15.4%~18.5%）最大,衣分变异系数（4.1%~4.7%）最小。‘新海43号’和‘新海49号’H3、H6、H9处理下单株结铃数分别减少21.6%、22.5%、28.9%和16.6%、26.4%、34.7%;而增温显著增加了上部果枝铃数,进而提高了上部果枝产量及产量贡献率。品种间,‘新海49号’净光合速率、单株结铃数和单铃重下降幅度以及蕾铃脱落率的增加幅度均大于‘新海43号’,说明‘新海43号’具有更好的耐热性。     

不同早、中熟基因型棉花品种的干物质积累及养分吸收规律研究

利用Logistic方程对2个早熟棉品种(中36、中50)和2个中熟品种(中41、鲁28)的单株干物质积累、N、P2O5、K2O吸收动态进行模拟研究,结果表明,早熟品种与中熟品种吸收积累养分的高峰期均在开花至吐絮期。2个早熟棉品种单株干物质质量、N、K2O积累快速增长持续时间短于中熟品种,P2O5积累快速增长持续时间略长于中熟品种。早熟品种在吐絮至收获阶段,干物质积累及养分吸收占全生育期的比例高于中熟品种,成熟单株对P2O5、K2O的吸收比例高于中熟品种,在肥料配比上可适度加大磷钾肥比例。     

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。     

不同硼效率棉花品种木质部和韧皮部汁液中矿质养分的差异

溶液培养条件下研究硼对2个硼效率不同的棉花品种木质部、韧皮部中硼及其它矿质养分运输的影响。结果表明,缺硼使2个棉花品种木质部汁液硼含量及溢出量明显降低,低效品种降低幅度大于高效品种。供硼充足(0.5mg/L)时,2个棉花品种木质部汁液中硼浓度均小于培养液中硼浓度;缺硼(0.002mg/L)时,高效品种与低效品种木质部汁液硼浓度分别是培养液硼浓度的32.0和20.5倍。缺硼使2个棉花品种木质部汁液中钾、锰、铜、锌含量均升高,高效品种升高幅度较大;钙含量均降低,低效品种降低幅度较大;高效品种镁含量增高,低效品种降低。而2个棉花品种木质部各养分(钾、镁、钙、锰、铜、锌)溢出量均降低,低效品种降低更明显。无论在缺硼或供硼充足时,2个棉花品种韧皮部中硼浓度均极低,但韧皮部溢泌液中其它养分受缺硼影响品种间表现不同,高效品种韧皮部钾、镁、锰、铜溢出量升高,低效品种则降低;2个品种钙、锌溢出量均降低,低效品种降低幅度更大。     

Growth response and ion homeostasis in two bermudagrass (Cynodon dactylon) cultivars differing in salinity tolerance under salinity stress

Bermudagrass (Cynodon dactylon) is a salinity-tolerant turfgrass that has good use potential in the saline-alkali lands of warm regions. However, the systematic Na⁺ and K⁺ regulation mechanisms under salinity stress remain unclear at the whole plant level. Two bermudagrass cultivars differing in salinity tolerance were exposed to 0, 50, 100, 200, or 300 mM NaCl in a hydroponic system. Growth, absorption, transportation, and secretion of Na⁺ and K⁺, and gas exchange parameters were determined in both cultivars. K⁺ contents were decreased and Na⁺ contents and Na⁺/K⁺ ratios were increased in both bermudagrasses with increased salinity; however, lower Na⁺ content and Na⁺/K⁺ ratio and more stable K⁺ content were found in the leaves of the salinity-tolerant ‘Yangjiang’ than the salinity-sensitive ‘Nanjing’. Higher Na⁺ contents in root cortical cells were found than in the stele cells of ‘Yangjiang’, but the opposite was observed in ‘Nanjing’. Lower Na⁺ contents and higher K⁺ contents were found in vessels for ‘Yangjiang’ than for ‘Nanjing’. Salinity stress increased the selective transport of K⁺ over Na⁺ from roots to leaves and the Na⁺-selective secretion via salt glands, which were stronger in ‘Yangjiang’ than ‘Nanjing’. Net photosynthetic rate and stomatal conductance decreased in the two bermudagrasses with increased salinity; however, they were more stable in ‘Yangjiang’. The results suggested that bermudagrass could reduce Na⁺ accumulation and maintain K⁺ stability in leaves under salinity stress by restricting Na⁺ into vessels in roots, selectively transporting K⁺ over Na⁺ from roots to leaves, selectively secreting Na⁺ via leaf salt glands, and maintaining suitable stomatal conductance.     

不同基质中栽培的樱桃番茄在夏季热应激下的反应比较

该文旨在比较研究不同栽培基质(土壤、泥炭、泥炭／珍珠岩(1／2)、珍珠岩和营养液循环系统)中生长的樱桃番茄在夏季受热应激时的反应。试验于2002年7、8、9月进行，番茄分别移植到3个温室中，温度设置为：25/20℃，35/25℃，>35/>25℃，分别在番茄不同生长阶段进行。测试分析了温室内环境因子的变化和气体交互作用：温室内温度与湿度(R²：0.894～0.972)、温度与CO₂浓度(R²：0.668～0.786)之间呈线性关系。测定了番茄的生长率，表明茎伸展与栽培基质密切相关。用叶水势来反映受热应激下番茄的水分状况，表明方差分析显示无论是黎明前还是正午，栽培基质和热应激对叶水势的变化有重要的作用。实验结果可正确确定热胁迫影响的生育时期，并为选择夏季番茄生产的适宜栽培基质提供依据。     

Effects of NaCl and silicon on ion distribution in the roots,shoots and leaves of two alfalfa cultivars with different salt tolerance

Abstract

The effects of exogenous NaCl and silicon on ion distribution were investigated in two alfalfa (Medicago sativa. L.) cultivars: the high salt tolerant Zhongmu No. 1 and the low salt tolerant Defor. The cultivars were grown in a hydroponic system with a control (that had neither NaCl nor Si added), a Si treatment (1 mmol L^?1 Si), a NaCl treatment (120 mmol L^?1 NaCl), and a Si and NaCl treatment (120 mmol L^?1 NaCl + 1 mmol L^?1 Si). After 15 days of the NaCl and Si treatments, four plants of the cultivars were removed and divided into root, shoot and leaf parts for Na⁺, K⁺, Ca²⁺, Mg²⁺, Fe³⁺, Mn²⁺, Cu²⁺ and Zn²⁺ content measurements. Compared with the NaCl treatment, the added Si significantly decreased Na⁺ content in the roots, but notably increased K⁺ contents in the shoots and leaves of the high salt tolerant Zhongmu No.1 cultivar. Applying Si to both cultivars under NaCl stress did not significantly affect the Fe³⁺, Mg²⁺ and Zn²⁺ contents in the roots, shoots and leaves of Defor and the roots and shoots of Zhongmu No.1, but increased the Ca²⁺ content in the roots of Zhongmu No.1 and the Mn²⁺ contents in the shoots and leaves of both cultivars, while it decreased the Ca²⁺ and Cu²⁺ contents of the shoots and leaves of both cultivars under salt stress. Salt stress decreased the K⁺, Ca²⁺, Mg²⁺ and Cu²⁺ contents in plants, but significantly increased Zn²⁺ content in the roots, shoots and leaves and Mn²⁺ content in the shoots of both cultivars when Si was not applied. Thus, salt affects not only the macronutrient distribution but also the micronutrient distribution in alfalfa plants, while silicon could alter the distributions of Na⁺ and some trophic ions in the roots, shoots and leaves of plants to improve the salt tolerance.     

不同铃重基因型棉花盛花期14C-同化物在"铃-叶系统"中的分配特征

以大铃、中铃和小铃3个不同铃重棉花基因型为材料,通过在盛花期测定棉株中部主茎和果枝叶面积及叶面积指数,并用^14CO2饲喂中部主茎叶,研究了^14CO2同化物在棉株不同层次“铃-叶系统”中的分配特征。结果表明,盛花期中部主茎和果枝单叶面积与铃重呈正相关。小铃基因型棉花群体盛花期叶面积指数最大;大铃基因型棉花蕾铃比中、小铃基因型表现出更强的库活性。主茎叶片产生的同化物除主要输送到对应的果枝外,还向上部、下部的库器官及主茎生长点输送;而流向其对应果枝的同化物,主要供应第一果节蕾铃。     

Effect of nitrogen supply on leaf traits related to photosynthesis during grain filling in two maize genotypes with different N efficiency

In the present study, plant traits related to the photosynthetic capacity at the whole plant level were compared during grain filling in two maize genotypes with different nitrogen (N) efficiency. The plants were grown in a greenhouse in large root containers and supplied either with suboptimal or optimal rates of N fertilizer. Suboptimal N supply reduced total plant biomass at maturity (47 days (d) after flowering) by 29 % for the efficient genotype and by 36 % for the inefficient genotype. Suboptimal N supply reduced leaf growth of both genotypes. The reduction of leaf area was less severe in the N‐efficient genotype, despite of lower N content in the leaves. This indicates lower sensitivity of leaf growth towards internal N limitation in the efficient genotype. At low N supply, the green leaf area per plant gradually decreased after flowering in both genotypes, because of loss of chlorophyll during leaf senescence. The rate of net photosynthesis per unit leaf area (A) was reduced at low in comparison with high N supply. The ratio of A/leaf N content or leaf chlorophyll content was higher in the efficient genotype, indicating more efficient utilization of internal N for photosynthesis. At the end of grain filling, low N supply led to enhanced intercelluar CO₂ concentrations (Ci) in the leaves, indicating limitation of CO₂ assimilation by carboxylation rather than by stomatal resistance. The N deficiency‐induced increase of Ci was less pronounced in the efficient genotype. Furthermore, higher photosynthetic rate of the efficient genotype at suboptimal N supply was associated with lower contents of reducing sugars and sucrose in the leaves, whereas starch content was higher than in the inefficient genotype. The ability to avoid excessive sugar accumulation in the leaves under N deficiency might be related to higher photosynthetic N efficiency.     

Comparative growth and physiological responses of two wheat (Triticum aestivum L.) cultivars differing in salt tolerance to salinity and cyclic drought stress

Two cultivars of wheat (Triticum aestivum L.) with differential salinity tolerance were compared by evaluating the growth attributes, pigment composition and accumulation of Na⁺, K⁺, Zn²⁺, Fe ²⁺, Mn ²⁺ and proline. Wheat cultivars Al-Moiaya (AM) (salt tolerant) and Habbe-Druma (HD) (salt sensitive) were subjected to four levels of salinity (1.21 dS m^?1, 4.4 dS m^?1, 8.8 dS m^?1 and 13.2 dS m^?1) in factorial combinations with three drought stress (FC 30%, FC 60% and FC 90%) treatments in a randomized complete block design. Plant dry weight, leaf area ratio (LAR), soluble protein and total chlorophyll (Chl) content were higher in AM than HD. Salt-tolerant AM maintains a higher K⁺/ Na⁺ ratio and thereby is able to grow better than the salt-sensitive HD under both the stresses. The lower foliar Na⁺ in AM resulted in retention of higher Chl content, reflected in the strong positive correlations between plant ion status and Chl contents (Na⁺-Chl r² = 0.83; Chl- Fe²⁺ r² = 0.76; Zn²⁺ r² = 0.93 and Mn²⁺ r² = 0.88). In conclusion, our results suggested that the K⁺/Na⁺ ratio, exclusion of Na⁺ and ion homeostasis play much more important roles in the tolerance to salinity and drought stress than the compatible osmolyte, proline.     

不同施氮水平下棉花叶片最大羧化速率的高光谱估测

植物叶片最大羧化速率（Maximum Carboxylation Rate,Vcmax）是表征植被光合能力的重要参数之一,研究叶片Vcmax对氮素的响应对预测植被光合作用和未来植被生产力具有重要意义。该研究以国欣棉9号为试验材料,设置4个施氮水平,测定棉花不同生育时期叶片生理参数和叶片反射光谱,探究Vcmax与生理参数及光谱指数的关系,建立叶片Vcmax最优反演模型。结果显示,棉花叶片Vcmax在苗期至蕾期不受施氮水平的影响,随着生育进程的推进,氮素逐渐成为影响叶片Vcmax高低的主要因素之一。此外,叶片Vcmax与含氮量的相关程度最高,远高于叶片Vcmax与叶绿素、比叶重的关系。对叶片Vcmax与光谱指数进行回归分析发现,由蓝光和红边波段组合的光谱指数能较好的预测叶片Vcmax,其中表现最好的为归一化差值植被指数（Normalized Difference Vegetation Index,NDVI697,445）和比值植被指数（Ratio Vegetation Index,RVI445,694）,决定系数（R2）均大于0.75。最后,以生理参数和光谱指数为基础,采用一般线性回归和多元逐步回归构建棉花叶片Vcmax估算模型,结果表明,由RVI445,694、光化学植被指数（Photochemical Vegetation Index,PRI）、修正型归一化差值植被指数（Modified Normalized Difference Vegetation Index,mND705）所构建的多元逐步回归模型精度最高（R2=0.809,RMSE=16.93 μmol/(m2?s)）,叶片含氮量和叶绿素所构建的多元逐步回归模型次之（R2=0.801,RMSE=17.01 μmol/(m2?s)）,高于其他单变量线性回归模型。研究表明,利用高光谱指数可以有效地估测棉花叶片最大羧化速率,结果可为叶片Vcmax准确反演和评估光合能力提供支撑。     

种植密度对新疆膜下滴灌棉花群体光合速率、冠层结构及产量的影响

田间试验研究了3个水平的种植密度(21万株/hm2、24万株/hm2、27万株/hm2)对膜下滴灌棉花群体光合速率(CAP)、冠层结构及产量的影响。结果表明北疆棉区适宜播种条件下,24万株/hm2密度的群体冠层结构优于其他密度,生育后期仍可保持较高CAP,叶面积指数高值持续期进入早、持续时间长,光合物质累积多且分配到生殖器官中的比例大,皮棉产量较高。     

适宜膜下滴灌频次提高北疆机采棉光合能力及产量

在北疆大田条件下,以机采棉品种新陆早57号为供试材料,研究不同灌水分配对机采棉光合特性和产量形成的影响。试验设滴灌定额为4 500 m~3/hm~2,3个灌水分配次数分别为10次(D10)、8次(D8)、6次(D6)。结果表明:D6处理头水时间推迟,由非气孔限制因素导致净光合速率的下降,胁迫程度较高,最大光化学效率、光化学猝灭系数、光化学量子产量显著低于其他处理(P0.05),非光化学淬灭系数明显增加,同时恢复能力较差,地上部分生物量积累受限。盛蕾后充分供水但并没有较高的补偿强度,且蒸腾速率较高,叶片水分利用效率降低。由于D10处理花铃期灌量分配不合理,净光合速率的下降主要受气孔限制因素影响,棉株受到轻度胁迫,吐絮期的灌水有效提高了其光化学猝灭系数,与D6处理差异显著。降低了非光化学淬灭系数,延长了叶片光合功能期,生物量积累偏向营养生长,使其营养器官显著高于其他处理,但生殖器官差异不显著(P0.05),不利于产量的形成。而D8处理在整个生育期保证了高效的光合生产能力,明显提高了光合物质向生殖器官运移的比例,比D10、D6处理高出21.1%、23.5%,叶片水分利用效率表现最优,且产量与D10差异不显著,但比D6处理显著高647.4 kg/hm~2(P0.05)。因此在滴灌定额为4 500 m~3/hm~2的条件下,配合D8处理的灌水分配方式,有利于提高叶片光合能力,促进光合物质优先向生殖器官分配,从而获得高产。由此可见,盛蕾前灌头水且增加盛花期后灌溉定额,同时减少吐絮期水分供应,可有效提高叶片光合生产能力,促进光合物质优先向生殖器官运移,实现机采棉节水高产高效。     

转Bt抗虫棉和土壤营养与红叶茎枯病严重度的关系

在棉田土壤营养丰富的条件下,观察了转Bt基因抗虫棉和非抗虫棉对红叶茎枯病的感病性。结果表明,转Bt抗虫棉的发病程度均高于非抗虫棉,前者的发病率、病情指数依次为47．95％～79．45％和12．95～28．25;后者的发病率、病情指数依次为32．12％～55．06％和9．09～15．75;两类品种间的发病率差异显著(P<0．05)。N、P、K不同用量配方施肥试验结果表明,各处理间红叶茎枯病的严重度和皮棉产量均无显著差异(P>0．05),表明增施K肥或N、P、K肥配施,对减轻抗虫棉红叶茎枯病的严重度无明显作用。据此提出了红叶茎枯病减灾的新理论和新方法。     

不同温度型小麦K+吸收动力学特征及其盐胁迫效应

本试验采用吸收动力学方法结合药理学方法,研究了NR9405（暖型）、小偃六号（中间型）、RB6和陕229（冷型）等4种不同温度型小麦幼苗（14 d）K+ 的高亲和和低亲和吸收特征。结果表明: 1）在0～50mmol/L的K+浓度范围内,K+吸收可分为0～1和1～50mmol/L两个阶段,均可用米氏方程描述;2）对于高亲和吸收系统（0～1 mmol/L）,冷型小麦具有高的饱和吸收率Imax [42.46～43.12 mol/（h?g）,RDW]和亲合系数Km（0.430～0.432 mmol/L）,暖型小麦（NR9405）和小偃六号具有较低的Imax［33.57～35.38 mol/（h?g）,RDW］和Km（0.332～0.353 mmol/L）,抑制低亲和系统后增加了4种小麦的高亲和转运载体数量,降低了冷型小麦对K+的亲和力,但对NR9405和小偃六号的Km值影响较小; 3）抑制高亲和吸收后,低亲和系统的Imax和Km均增加; 4）在盐胁迫下,K+高亲和和低亲和吸收系统均受到抑制,小麦幼苗K+吸收能力均显著降低,暖型小麦NR9405和小偃六号的高亲和系统Km几乎不受盐胁迫的影响,而冷型小麦的Km值因盐胁迫而降低。因此,在盐胁迫下高亲和吸收系统的稳定性可能是影响暖型小麦耐盐性高的一个重要因素,这对小麦耐盐性研究及耐盐品种选育均具有一定的指导意义。     

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。     

水分胁迫对棉花光合产物在下部“铃-叶系统”中运转分配的影响

为了解棉花叶片光合产物在干旱环境下的运转分配规律,在防雨棚中设置不同水分条件对棉花进行了研究。通过利用~(14)CO_2在棉花的盛蕾期、盛花期对棉花下部主茎叶片进行饲喂,研究在严重胁迫(SS)、中度胁迫(MS)、以及对照(CK)3个不同水分处理环境下~(14)C光合产物在棉株下部"铃-叶系统"中的运转与分配特征。结果表明,随着水分亏缺程度的加重,~(14)C光合产物在标记叶中滞留量增加,向外输出量减少;所产生的光合产物向幼铃和根部输送的比率增加,向成铃与主茎生长点的分配比率下降。对纤维品质的测定结果表明,在棉花生长的前期,适当的干旱胁迫不会对纤维品质造成显著的影响。