遮阴对南疆冬小麦光合特性和产量的影响

【目的】在小麦生长中后期,采用人工模拟核桃、杏、红枣三种果树不同程度遮阴条件下,研究分析不同遮阴处理对小麦光合特性、干物质积累及分配和产量的影响,为新疆南疆果树-小麦间作模式下小麦高产栽培管理提供理论依据。【方法】供试冬小麦品种为新冬20号,遮阴处理设置4个水平,S1:拔节期遮阴10%-抽穗期遮阴25%,S2:拔节期遮阴20%-抽穗期遮阴50%,S3:拔节期遮阴30%-抽穗期遮阴75%,S0:不遮阴。遮阴均从小麦拔节期至成熟期。【结果】小麦扬花期随着遮阴幅度的增大,小麦旗叶光合速率显著降低;灌浆期轻度遮阴Pn与对照无明显差异,但显著高于S2和S3处理;蒸腾速率和气孔导度均随着遮阴幅度的增大而降低,胞间CO₂浓度随着遮阴幅度的增大而增大。随着遮阴幅度的增大总干物质积累量和向籽粒的分配均呈降低趋势,干物质向籽粒的分配率分别降低9.5%、24.2%和27.7%;收获穗数、千粒重、产量和经济系数均随着遮阴幅度的增大而显著降低,而轻度遮阴对穗粒数的影响不明显。随着遮阴幅度的增大,产量和经济系数分别降低22.%、42.9%、67.8%和 8.9%、23.8%、27.6%。【结论】随着遮阴幅度的增加,小麦光合速率、蒸腾速率和气孔导度降低,胞间CO₂浓度升高,总干物质积累量和向籽粒的分配比例降低,轻度遮阴收获穗数和千粒重降低,中度和重度遮阴产量三要素均显著降低,导致产量和经济系数显著降低。     

Productivity and nutritive value of Brachiaria decumbens and performance of dairy heifers in a long‐term silvopastoral system

Silvopastoral system (SPS) has been suggested to ensure sustainability in animal production systems in tropical ecosystems. The objective of this study was to evaluate the productive and nutritive value traits of Brachiaria decumbens and performance of dairy heifers in SPS and open pasture (OP) during the summer and autumn of two consecutive years in the SPS and OP (17th and 18th years after establishment). Experimental design was a randomized complete block with two treatments (SPS and OP) and three replications in subdivided plots with repeated measures in time. There was reduction in the tiller population density, total and green forage mass, and total and green forage bulk density in the SPS when compared to the OP in the summer. In the autumn, no difference was observed between the systems. Shading in SPS increased crude protein content of the grass pasture by 25% and 33% when compared to the OP during the first and second experimental years, respectively, and reduced neutral detergent fibre content. However, it did not change acid detergent fibre or lignin content. OP provided higher stocking rate and weight gain per area than the SPS. Average daily gain was higher in the OP in the second experimental year. Severe shading conditions should be avoided, because in the long ‐ term they may threaten the persistence and sustainability of pasture in the SPS. It is recommended to plant a low density of trees or implement management strategies of the tree component by either thinning or pruning over the years after planting.     

甜瓜叶片光合产物输出能力对弱光的响应

【目的】研究甜瓜果实发育期坐果节位叶片光合能力、蔗糖合成能力和水苏糖装载能力对遮光的响应,分析不同耐弱光性甜瓜品种同化物输出能力的差异,为进一步研究甜瓜耐弱光品种果实糖分卸载与积累机理奠定基础。【方法】以耐弱光甜瓜品种‘玉金香’和不耐弱光品种‘钰雪三号’为试材,在日光温室条件下于授粉后进行遮光处理,每5 d取样一次,取坐果节位叶片测定叶绿素含量、气体交换参数、葡萄糖、果糖、蔗糖、肌醇半乳糖苷、棉子糖、水苏糖和淀粉含量,同时测定叶片蔗糖磷酸合成酶（SPS）、蔗糖合成酶（SS）、中性转化酶（NI）、酸性转化酶（AI）、肌醇半乳糖苷合成酶（GS）和水苏糖合成酶（STS）活性。【结果】遮光处理后,两个甜瓜品种叶片叶绿素a/b、净光合速率（Pn）、葡萄糖、果糖和蔗糖含量均显著降低,淀粉含量升高,‘玉金香’叶绿素a/b降幅（10.0%）大于‘钰雪三号’（5.8%）,而Pn、蔗糖含量降幅（分别为30.3%和30.9%）和淀粉含量增幅（3.6%）均显著小于‘钰雪三号’（分别为45.2%、60.6%和20.4%）。遮阴条件下,两个品种叶片蔗糖代谢相关酶SPS、SS、AI和NI活性均显著降低,‘玉金香’SPS和SS酶活降幅（分别为16.5%和30.0%）显著小于‘钰雪三号’（31.6%和40.5%）,而AI和NI降幅（分别为23.8%和12.7%）高于‘钰雪三号’。遮光后甜瓜叶片肌醇半乳糖苷含量和GS活性均显著降低,但品种间差异不显著。棉子糖、水苏糖和STS活性均显著降低,‘玉金香’棉子糖含量降幅（65.3%）显著高于‘钰雪三号’（35.0%）,而水苏糖和STS活性降幅（分别为79.5%和23.8%）小于‘钰雪三号’。【结论】遮光条件下,耐弱光品种‘玉金香’叶片蔗糖合成能力和水苏糖装载能力下降较少,具有较强的同化物输出能力。     

遮阴对珠子参生长发育及光合生理特性的影响

为探明遮阴对珠子参生长发育和光合生理特性的影响,对盆栽珠子参分别采取全光照、30%遮阴和50%遮阴3种处理。在珠子参生长90天后,考察各处理下珠子参植物学性状、生理指标和光合特性。结果表明,与全光照相比,30%遮阴处理下珠子参株高、主茎粗、果实数、根茎直径、叶绿素含量、SOD和POD活性增加,地下根茎节间长度和叶MDA含量减小。遮阴处理后珠子参净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)低于全光照处理,胞间CO2浓度(Ci)则高于全光照处理。遮阴有效地缓解了珠子参的“午休”并降低了光抑制,其中,30%遮阴处理效果最显著,为珠子参的生长提供了较为适宜的环境。     

遮阴对不同冬小麦品种籽粒灌浆及品质特性的影响

【目的】研究遮阴处理对不同冬小麦品种籽粒灌浆及品质特性的影响,为耐阴小麦选育提供理论基础。【方法】在大田灌溉条件下,以新冬20号、新冬40号、新冬57号和新冬60号为材料,分别设置自然光对照和遮光度为50%的遮阴处理,研究不同冬小麦品种在遮阴和自然光条件下籽粒灌浆特性、品质特性及产量的变化规律。【结果】 遮阴处理后,四个冬小麦品种的籽粒灌浆特性表现为:新冬57号＞新冬60号＞新冬40号＞新冬20号,各品种的蛋白质含量、湿面筋含量和沉降值均表现为:新冬20号＞新冬57号＞新冬40号＞新冬60号;新冬57号的形成时间最长,为5.7 min;新冬60号的稳定时间最长,为11.6 min;面团拉伸特性表现为:新冬60号＞新冬20号＞新冬40号＞新冬57号;产量表现为:新冬40号＞新冬57号＞新冬20号＞新冬60号。【结论】遮阴显著降低了四个冬小麦品种的灌浆特性及产量,对品质特性也有一定的影响。     

Effects of planting dates and shading on carbohydrate content,yield, and fiber quality in cotton with respect to fruiting positions

Two cotton (Gossypium hirsutum L.) cultivars, Kemian 1 (cool temperature-tolerant) and Sumian 15 (cool temperature-sensitive) were used to study the effects of cool temperature on carbohydrates, yield, and fiber quality in cotton bolls located at different fruiting positions (FP). Cool temperatures were created using late planting and low light. The experiment was conducted in 2010 and 2011 using two planting dates (OPD, the optimized planting date, 25 April; LPD, the late planting date, 10 June) and two shading levels of crop relative light rate (CRLR, 100 and 60%). Compared with fruiting position 1 (FP1), cotton yield and yield components (fiber quality, leaf sucrose and starch content, and fiber cellulose) were all decreased on FP3 under all treatments. Compared with OPD-CRLR 100%, other treatments (OPD-CRLR 60%, LPD-CRLR 100%, and LPD-CRLR 60%) had significantly decreased lint yield at both FPs of both cultivars, but especially at FP3 and in Sumian 15; this decrease was mainly caused by a large decline in boll number. All fiber quality indices decreased under late planting and shading except fiber length at FP1 with OPD-CRLR 60%, and a greater reduction was observed at FP3 and in Sumian 15. Sucrose content of the subtending leaf and fiber increased under LPD compared to OPD, whereas it decreased under CRLR 60% compared to CRLR 100%, which led to decreased fiber cellulose content. Therefore, shading primarily decreased the “source” sucrose content in the subtending leaf whereas late planting diminished translocation of sucrose towards cotton fiber. Notably, as planting date was delayed and light was decreased, more carbohydrates were distributed to leaf and bolls at FP1 than those at FP3, resulting in higher yield and better fiber quality at FP1, and a higher proportion of bolls and carbohydrates allocated at FP3 of Kemian 1 compared to that of Sumian 15. In conclusion, cotton yield and fiber quality were reduced less at FP1 compared to those at FP3 under low temperature and low light conditions. Thus, reduced cotton yield and fiber quality loss can be minimized by selecting low temperature tolerant cultivars under both low temperature and light conditions.     

幼苗期遮阴对云南春作马铃薯生长和产量的影响

通过2015~2016年两年的田间试验,用遮光率为70%的黑色遮阳网进行不同遮阴处理,其中2015年设置幼苗期遮阴处理(出苗后遮阴15d),2016年设置90d(全生育期)遮阴、前15d遮阴、前30d遮阴、前60d遮阴、后60d遮阴、中间30d遮阴、后30d遮阴7个处理,均以不遮阴作对照,研究幼苗期遮阴对云南春作马铃薯生长和产量的影响。结果表明,幼苗期遮阴能够促进马铃薯茎叶快速生长,其株高、节长和叶面积较对照分别增加179.03%、163.41%、61.68%,差异极显著。遮阴后,对茎的生长最有利,茎鲜重、茎叶鲜重和总生物量较对照分别增加286.23%、151.55%、136.66%,差异显著。两年的数据表明,幼苗期遮阴处理单株结薯数较对照增加11.67%~58.06%,单株产量较对照增加17.78%~41.05%,并有较高的商品薯重比率,2015年略低于对照,2016年较对照高4.34%。不同年份效果不一样,与遮阴期间天气有关。遮阴处理较不遮阴处理均会导致结薯减少,产量降低。     

遮阴对10种野生观赏植物生长及生理特性的影响

为了探讨野生观赏植物在遮阴条件下的生态适应性及寻求适度的遮阴比例,选取兰州地区10种野生观赏植物为试验材料,比较测定不同光强生境(全光照、25%、50%、70%遮光率)对10种野生观赏植物生长和生理生化的影响。结果表明,角茴香(Hypecoum erectum)和驴蹄草(Caltha palustris)含水率随着遮阴度的增加而增加,小花草玉梅(Anemone rivularis)在75%遮阴度时干重最大,显著高于其余遮阴处理及全光照(CK)(P0.05);藤本铁线莲(Clematis florida)可溶性糖含量随着遮阴度的增加而减少,鹅绒委陵菜(Potentilla anserina)、角茴香、水杨梅(Geum aleppicum)和驴蹄草的叶绿素含量随着遮阴度的增加而增加;东方草莓(Fragaria orientalis)、角茴香和驴蹄草在全光照下丙二醛的含量显著高于其它处理(P0.05),香青(Anaphalis sinica)和水杨梅在75%遮阴度下丙二醛含量较高。综上所述,香青、莓叶委陵菜(Potentilla chinensis)、藤本铁线莲和野棉花(A.vitifolia)比较适合全光照生长;鹅绒委陵菜、小花草玉梅、东方草莓、角茴香和水杨梅可以忍耐适当的遮阴环境;驴蹄草适合在遮阴条件下生长。     

烟株砍收遮光水养对东北烤烟低温减灾的成效

为破解东北烟区烤烟生长后期低温影响烟叶采收的障碍,提高烟叶质量,尝试将低温灾害风险预警等级划分成正常、低风险、中风险、高风险,在中风险和高风险临近时(前2 d),采取对烟株砍收遮光水养采烤的措施,分析其对烤后烟叶的经济性状、外观质量、化学成分含量及感官质量的影响。结果表明：当预警等级为中风险以下时,烟株砍收遮光水养采烤处理,烤坏烟损失率较常规采烤降低8.5%,总损失率降低12.6%,烟叶外观质量评价总分可提高0.06分,但外观和感官质量改善不明显;当预警等级为高风险时,烟株砍收遮光水养采烤处理,烤坏烟损失率降低55.1%,总损失率降低70.2%,上等烟和中等烟比例显著提高78.7%、57.2%,外观质量评价总分显著提高了0.58分,两糖比、糖碱比较高,改善了化学成分的协调性及感官质量。建议当低温灾害风险预警等级为中风险及以下时,对田间未达成熟标准的烟叶,采用常规采烤方法;当高风险临近时,则采用烟株砍收遮光水养采烤方法,以达到减灾保收的目的。     

幼穗分化期氮肥用量降低水稻遮光减产效应研究

【目的】探讨水稻幼穗分化期氮肥用量对遮光导致的水稻减产效应的作用,为水稻遭遇寡照稳产 栽培提供理论依据。【方法】以超级稻品种桂农占为试验材料,幼穗分化期氮肥用量 0 k g/hm2（N0）、22.5 kg/ hm2（N1）、37.5 kg/hm2（N2）和 52.5 kg/hm2（N3）为主区,幼穗分化二期至成熟期不遮光（S0）、幼穗分化二 期至齐穗期遮光（S1）、齐穗期至成熟期遮光（S2）、幼穗分化二期至成熟期遮光（S3）为副区,进行大田裂 区试验,研究幼穗分化期氮肥不同用量与幼穗分化后不同遮光时间对水稻生育进程、茎蘖特征、产量及其构成 的影响。【结果】不同氮肥水平下,水稻产量均表现为处理 S0 ＞ S1 ＞ S2 ＞ S3。相较于 S0,处理 S1、S2 和 S3 分别减产 32.0%、52.7%、67.8%,且差异显著;增施氮肥降低了遮光导致的减产幅度,在 S1、S2、S3 处理下, 处理 N2 和 N3 水稻产量较 N1 分别提高 3.9% 和 4.3%、4.4% 和 6.8%、0.9% 和 3.1%;同时分析发现增施氮肥延 长了遮光处理下水稻的籽粒灌浆期,减少了成穗率、有效穗数、实粒数和千粒重的降低幅度。【结论】增施穗 肥氮素用量可延长幼穗分化期后遭遇寡照水稻的籽粒灌浆期,降低遮光对水稻产量及构成因素的影响,在一定 程度上降低遮光导致的水稻减产效应。其中增施氮肥对 S2 处理的稳产效果最好,其次为 S1。