抽穗前后遮光对超级粳稻产量形成的影响

大田条件下以超级粳稻南粳44和宁粳3号为材料,设置3种遮光处理(L0:不遮光,L1:抽穗前遮光20d,L2:抽穗后遮光20 d),研究抽穗前后遮光对超级粳稻产量形成的影响。结果表明,抽穗后遮光处理的产量高于抽穗前遮光的处理,但都低于不遮光的处理(产量L0L2L1)。其中,与L0相比,L1降低了抽穗期LAI、粒叶比及拔节至成熟阶段的干物质积累量,同时增加了齐穗后剑叶SPAD值和净光合速率,表现为贪青迟熟;与L0相比,L2主要影响了抽穗至成熟阶段的光合物质积累,但L2对粒叶比和SPAD值的影响大于L1。株型特征方面,与L0相比,L1降低了齐穗期水稻穗长和倒3叶的透光率,增加了株高及上3叶的叶基角、叶开角、披垂度。     

不同穗型不同行向水稻穗遮光问题理论研究

分析了不同穗型不同行向水稻穗对行间的遮光时间、遮光部位及遮光长度,结果表明穗遮光时间在临界高度以上南北行向比东西行向长。对南北行向,穗遮光部位上午随时角的增加逐渐向下移动,东西行向在临界高度以上与南北行向趋势相似,在临界高度以下则随时角的增加先逐渐向下移动,而后又向上移动至临界高度。穗遮光长度在0至穗长之间。对比不同重量穗型可知,弯曲穗型穗对行间遮光影响小,对行内遮光影响大。     

苗期遮荫对大豆茎秆形态和物质积累的影响

麦/玉/豆套作模式下,玉米的株型直接关系着低层大豆前期生长的荫蔽程度.采用室外盆栽模拟试验,设置遮荫35%、45%、55%三个处理,以不遮荫为对照,研究了苗期不同遮荫程度对大豆茎秆形态和物质积累的影响.结果表明,遮荫35%可能是贡选1号盆栽条件下茎正常生长的临界光强.苗期遮荫程度越大,干物质在茎中的积累速率越快,向茎中的分配比例越大,但基部节间(子叶节、基部第一节、基部第二节)单位干重增长越慢.V9期恢复自然光照后,苗期遮荫的影响逐渐减弱,干物质在茎中的积累速率及在茎中的分配比例、基部节间单位干重增长速率均逐渐恢复到对照水平,且子叶节、第一节单位干重的增长在R4～R6期出现补偿效应.在苗期遮荫条件下,茎粗、茎干重、茎(主茎、基部节间)单位干重、主茎纤维素含量与倒伏率显著负相关,主茎木质素含量与倒伏率极显著负相关.可见,苗期遮荫显著影响了大豆茎秆的形态发育和物质积累,荫蔽程度小,大豆茎秆发育良好,不易倒伏.在实际生产中,应选择株型较为紧凑的玉米品种,以减缓大豆生长过程中的弱光胁迫.     

荷兰Venlo型连栋温室夏季自然通风降温系统的试验研究

针对我国气候条件下，大型连栋温室夏季自然通风降温效果差，而机械通风降温成本较高的问题，对采用自然通风并结合遮阳网、室外屋顶喷淋降温措施的荷兰引进Venlo型玻璃温室的室内温湿度状况进行了测试。结果表明：连栋温室室内空气温度明显低于室外，且室内温湿度分布比较均匀，能够满足作物生长需求。室外屋顶喷淋的降温效果显著，而且未造成温室内湿度显著增加。这种自然通风降温系统的能耗小，在中原地区使用可以达到温室降温和降低温室夏季生产成本的双重目的。     

遮阳网在鹤望兰生产上的应用

通过实测资料说明：遮阳网使棚内０．５ｍ及以下气层降温,０．５ｍ气温平均降低０．３℃,０．１ｍ平均降低０．９℃,０ｃｍ,５ｃｍ,１０ｃｍ土温平均降低５．０℃,３．１℃和２．６℃。相对浊度基本为适宜生长范围。而网外及棚内叶面喷水使生态环境更佳。     

水稻耐光氧化和耐阴特性的鉴定及其生理基础

水稻耐光氧化和耐阴特性的鉴定及其生理基础焦德茂，高亮之，金之庆，季本华，严建民（江苏省农业科学院，南京２１００１４；南通师范专科学校，南通２２６００７）关键词：光氧化；耐阴；光合特性ＩｄｅｎｔｉｆｉｃａｔｉｏｎａｎｄＰｈｙｓｉｏｌｏｇｉｃａｌＢａｓｉ...     

不同遮荫度对柱花草10^#生长和光合特性的影响

研究了不同遮荫度（O％,50％,75%）和遮荫期限（60d,120d）对柱花草10^#光合特性和生长的影响。结果表明：短期遮荫（60d）导致叶片的光合速率和蒸腾速率下降,水分利用率WUE增加,植物量和根冠比减小,并且759／6遮荫处理与对照之间出现显著的差异（P〈O．05）,遮荫使叶片含水量、叶绿素含量显著增加,75％遮荫与对照有显著差异（P〈O．05）。长期遮荫（120d）使75％处理的叶绿素总量降低,植株高度、分蘖数比对照显著降低（P〈O．05）,叶片含水量的变化却不显著。     

Restoration of tuber production by exposure to unshaded daylight in Eleocharis kuroguwai Ohwi shaded during the early tuber formation period

The loss of final tuber weight of Eleocharis kuroguwai Ohwi by shading during the early tuber formation period (TFP) is overcome by exposure to unshaded daylight thereafter (late TFP). In the present study, the growth parameters that contribute to the dry matter increase (DMI) per day of tubers in the late TFP were examined. DMI of the tuber during the late TFP was determined by that of the whole plant and the ratio of the DMI of the tuber to that of the whole plant during this period. The ratio of the DMI of the tuber to that of the whole plant during the late TFP was significantly correlated with the DMI of the whole plant during the first 14 days of the late TFP. During the late TFP after the exposure to unshaded daylight, DMI of the whole plant correlated with the surface area of the stem (SAS) and net assimilation ratio (NAR), and the SAS correlated with the stem dry weight (DW) and specific stem-surface area (SSA). SSA negatively influenced NAR, but NAR was increased by unshading. During the late TFP after shading, the effect of the decrease of the stem DW due to shading on the DMI of the whole plant was mitigated by the large SAS and high NAR. These results indicate that the growth parameters that contribute to the DMI of tuber during the late TFP after exposure to unshaded daylight are SAS and NAR just after unshading, and SSA during this period.     

The effect of non-inversion tillage and light availability on dispersal and spatial growth of Cynodon dactylon

The invasive ability of Cynodon dactylon is dependent on self dispersal and on cultivation practices. Tillage can seriously change patch biomass and spatial structure, spreading vegetative propagules of the weed. The objectives of this study were: (i) to quantify the effect on non‐inversion tillage on dispersal, establishment and colonization of C. dactylon and (ii) to propose a simple model considering soil cultivation effects and light availability on spatial growth of weed patches. Two experiments were carried out, exploring different soils and environmental conditions. Spatial distribution of vegetative units differed when tillage was conducted with different non‐inversion implements and could be described by simple functions. A minimum patch biomass seems necessary before vegetative structures are vulnerable to movement by cultivation. Only a small proportion of the biomass dispersed from original patches was able to establish. However, simulation showed that the area colonized by C. dactylon mostly increased by means of tillage dispersal, both with and without crop competition, in one growing cycle. It appears sensible to consider changing cultivation practices to reduce weed dispersal and to use crop competition for light to create unsuitable habitats limiting weed colonization.     

Shading effects on spatial growth and biomass partitioning of Cynodon dactylon

Cynodon dactylon is a low-growing C4 weed that is highly sensitive to shading. This species shows severe biomass reductions and highly plastic morphological changes in response to resource availability. The objective of this study was to analyse the effect of shading on the spatial and biomass growth of C. dactylon . Two experiments were carried out exploring different environmental conditions. Six treatments were applied on C. dactylon patches. Daylight and 18%, 41%, 48%, 69% and 85% shading of daylight photosynthetic active radiation (PAR) were imposed in Expt 1 and 0%, 22%, 44%, 50%, 74% and 87% shading of daylight PAR in Expt 2. Patches were slightly elliptical in shape and grew 3.2 and 1.5 cm d⁻¹ with 0% shading, on average, during the whole studied periods in Expts 1 and 2 respectively. Biomass was significantly reduced from 41% shading onwards in Expt 1 and from 50% shading in Expt 2. However, patch extension rate was only significantly reduced from 85% and 74% shading in Expts 1 and 2 respectively. Biomass partitioning was modified by shading in both experiments. A functional analysis of C. dactylon patches showed that the patch extension rate diminished linearly when patch biomass growth rate was lower than 1.66 g d⁻¹; above this value, the extension rate remained constant.