遮荫对两种灌木光合特性及叶绿素荧光参数的影响

以金叶女贞、胶东卫矛为试材,采用人工遮荫的方法,研究了全光照的8%、20%、50%、100%光照强度对2种灌木光合特性及叶绿素荧光参数的影响,以期探讨其对弱光环境的适应性。结果表明:随着遮荫程度的增加,2种灌木株高、叶面积增加,叶片含水量、叶绿素含量上升,而叶片厚度变薄,比叶重、叶绿素a/b下降;净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)先升后降,胞间CO₂浓度(Ci)降低;遮荫处理下2种灌木光系统Ⅱ(PSⅡ)最大光化学效率(Fv/Fm)增加,金叶女贞PSⅡ的实际光能转换效率(Fv′/Fm′)下降,胶东卫矛的Fv′/Fm′上升,金叶女贞非光化学淬灭系数(NPQ)显著增加,胶东卫矛的NPQ显著下降;遮荫提高了2种灌木表观量子效率(AQY),降低了光补偿点(LCP),金叶女贞在20%、胶东卫矛在50%光照条件下,最大净光合速率(Pn_max)和光饱和点(LSP)均达到最大值。2种灌木对不同光环境表现出较强的适应性,具有一定的适应弱光环境的能力。     

遮光处理对谷子农艺性状、小米品质及蒸煮特性的影响

为探讨弱光胁迫对谷子农艺性状、小米品质及蒸煮特性的影响，并为黄土高原低洼地带谷子种植提供理论数据，以长生13号为材料，2018—2019年重复调查其在4种遮光程度(正常自然光照为A1、遮光面积30%为A2、遮光面积50%为A3、遮光面积70%为A4)下的农艺性状、产量、干物质量、小米品质及蒸煮特性变化情况。结果表明：遮光程度的增加显著降低了谷子穗粗、穗重、穗粒重、单株干物质量和产量，其中A1处理与A4处理间的产量减幅2018年为1 695.11 kg·hm^-2、2019年为1 774.95 kg·hm^-2；相对叶绿素含量（SPAD）也是随着遮光程度的增加而降低，其中A4处理SPAD均值比A1处理2018年减小2.18、2019年减小2.68；而峰值粘度、直链淀粉、胶稠度、脂肪含量均是随着遮光程度的增加而先增后减。相关性分析表明，产量与遮光程度呈显著负相关，2018、2019年相关系数分别为-0.899、-0.917。     

遮阴对桢楠幼苗生长和光合生理特性的影响

【目的】了解不同光照条件下桢楠(Phoebe zhennan)幼苗的生长状况和光合生理特性,探讨有利于桢楠幼苗生长发育的最佳光照条件。【方法】采用遮阴方式模拟不同光照强度(即全光照、遮阴率50%、75%和87.5%4个水平),分析桢楠幼苗形态生长、光合色素含量、叶绿素荧光参数等光合特性的响应规律。【结果】(1)随遮阴程度的增强,桢楠幼苗的株高生长量呈先升后降的趋势,地径生长量逐渐减小;(2)遮阴造成桢楠幼苗叶绿素总量、类胡萝卜素含量增加,叶绿素a/b值降低;净光合速率P_n、蒸腾速率T_r、气孔导度G_s、表观量子效率AQY、光饱和点LSP、最大净光合速率P_(n max)均随遮阴程度的增强而先升后降,光补偿点LCP、暗呼吸速率R_d、光呼吸速率R_p均逐渐降低;(3)遮阴下PSⅡ潜在活性F_v/F_0、PSⅡ最大光化学量子产量F_v/F_m、PSⅡ有效光化学量子产量F_v′/F_m′、PSⅡ实际光化学量子产量ΦPSⅡ、光化学淬灭系数q_P、光化学耗散比例P均有不同程度提升,非光化学淬灭系数NPQ、天线热耗散比例D下降。轻度遮阴能够提高桢楠幼苗光合性能,促进其生长发育,而重度遮阴下虽然其光捕获能力、光能利用效率较高,但光能的严重缺乏限制了其生长发育。【结论】桢楠幼苗对弱光环境的适应性较强,其最适遮阴率为50%。     

Grain-filling response of winter wheat (Triticum aestivum L.) to post-anthesis shading in a humid climate

To assess the impacts of clouds during the grain-filling period on the leaf senescence and yield of wheat (Triticum aestivum L.), we conducted a 4-year plot shading experiment in a well-drained Andosol in northern Japan. Plants were shaded after the beginning of anthesis in mid-June, which corresponds to a naturally cloudy period in the study region. The effect of shading depended on its synchronization with soil drying, which affected leaf senescence. Grain yield was determined by solar radiation at the beginning of the grain-filling period, except in 2015, which was a dry year. Later anthesis in 2016 and 2017 significantly reduced the number and weight of individual grains in the shading treatments. Moreover, “Kitahonami”, with late anthesis, showed a significantly slower increase in the individual-grain weight during the grain-filling process after shading than “Yumechikara”. When the duration between anthesis and shading was short, shading significantly reduced the number and weight of grains, and later anthesis makes it more likely that regional reduced light levels are encountered, resulting in fewer grains; the sensitivity of individual-grain weight to shading synchronized with an increase in grain protein contents. Our results suggest that in wet years, later anthesis makes it easier to encounter regional reduced light and fewer grains; in addition, insufficient light limits photosynthesis under shade and decreases yield.     

Coffee shade with Mimosa scabrella Benth. for frost protection in southern Brazil

Damage by radiative frosts is a major limiting factor for coffee cultivation in southern Brazil (south of 20° S latitude). The use of Mimosa scabrella (bracatinga) as a shade tree, to modify the local energy balance and thus prevent damage to the coffee plants, has been evaluated from 1986 to 1994. The study was carried out near Londrina, Parana State (23°23' S, 51°11′ W). During the experimental period, several radiative frosts with intensity ranging from moderate to very severe occurred at the site. Minimum coffee leaf temperatures during these events were 2 to 4 °C higher in the shaded plots. Due to frost protection, coffee bean yields on the average of 7 harvests were higher on the shaded plots. The potential of this system for frost protection in southern Brazil is discussed.     

Evaluation of tropical forage legumes under Pinus caribaea var hondurensis in Turrialba,Costa Rica

A number of tropical forage legume species were sown in Turrialba., Costa Rica, in plots in the open and under an even cover of Pinus caribaea var hondurensis of basal area 30m²/ha. Mean light level under the trees was 18% full sunlight. After 19 months, species showing good shade tolerance and adaptation to local conditions were: Centrosema spp., Desmodium spp., Flemingia congesta, Galactia striata. Species of poor performance in the shade were: Stylosanthes spp., Indigofera hirsuta, Cajanus cajan, Stilozobium sp.. Canavalia ensiformis, an annual, grew well in the shade, as did Lablab purpureus and Vigna unguiculata. It is suggested that further work be done on the shade tolerant species for eventual use as components of silvopastoral systems. Recommendations are made concerning germplasm collections, evaluation methodology and research for silvopasture development.

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Resumen Se sembraron especies diversas de leguminosas forrajeras en Turrialba, Costa Rica, en parcelas al descubierto y bajo una cobertura uniforme de Pinus caribaea var hondurensis con area basal de 30 m²/ha. El nivel medio de iluminación bajo los pinos era 18% del nivel a pleno sol. Despues de 19 meses las especies que mostraron buena adaptación a la sombra eran: Centrosema spp., Desmodium spp., Flemingia congesta, Galactia striata. Especies de bajo rendimiento en la sombra eran: Stylosanthes spp., Indigofera hirsuta, Cajanus cajan, Stilozobium sp., La planta anuál Canavalia ensiformis creció bien bajo sombra, como tambien lo hicieron Lablab purpureus y Vigna unguiculata. Se sugiere que se investiguen las especies mencionadas como bien adaptadas al sombreamiento para uso en sistemas silvopastoriles. Se presentan recomendaciones sobre colecciones de germoplasma, metodologia de evaluación y investigación para el desarollo de sistemas silvopastoriles.

     

越冬期几种覆盖措施对库尔勒香梨树干保温遮荫效果分析

采用稻草、麻绳、反光膜、涂白4种物理保温遮阴措施,动态监测越冬期间香梨树干在各种措施下的树干形成层温度,对比分析了不同覆盖措施的保温遮阴效果。结果表明,4种措施遮荫效果大小顺序为:稻草>反光膜>麻绳>涂白>对照,而保温效果大小顺序为稻草>麻绳>反光膜>对照>涂白,稻草的日较差最小,保温遮荫能力最强,可作保温材料;使用浅颜色的覆盖材料可降低香梨树干形成层温度变化幅度,从而降低树体受越冬伤害的可能性;离地面越近的树干越容易受到低温和强光的交错伤害。     

栽培模式对茶树叶片光合生理及茶叶品质的影响

研究了栽培模式对茶树叶片光合特性、光响应曲线及茶叶品质的影响.结果表明,模式Ⅰ(茶园内板栗株行距4 m×4 m的栽培模式,遮光度为50％～60％)的茶树叶片净光合速率变化呈现单峰型曲线,而模式Ⅲ(纯茶园,遮光度为0)和模式Ⅱ(茶园内板栗株行距4m×8m的栽培模式,遮光度为30 ～ 40％)茶树叶片净光合速率变化呈双峰曲线,有明显的“午休”现象.不同模式内茶树叶片净光合速率的峰值和日均值随着遮光度的增大而降低.模式Ⅱ和模式Ⅰ内茶树叶片光补偿点比模式Ⅲ全光照条件下分别降低了11.95％和27.41％,表明茶树叶片在弱光下可以降低其光补偿点来提高对弱光的利用,用于其自身的正常生长.不同模式内茶芽长、百芽质量均表现为模式Ⅰ＞模式Ⅱ＞模式Ⅲ;模式Ⅰ和模式Ⅱ内茶树叶片氨基酸含量显著高于模式Ⅲ,分别提高了58.14％和36.04％,模式Ⅰ与模式Ⅱ咖啡碱含量分别比模式Ⅲ高31.18％和29.83％;氨基酸、儿茶素及咖啡碱含量均为春季高于夏季.     

Measuring for solar heat gain through glass windows with shading system

通过热量平衡原理搭建了室内太阳辐射得热量的测量装置,对透过装有遮阳系统窗户进入室内的太阳辐射得热量进行了试验研究.试验中通过测量电加热量、风机功率,计算风机盘管换热量、围护结构传热量得到室内太阳辐射得热量.并通过运用太阳辐射得热量计算理论模型进行了分析,对测试结果进行了验证.结果表明,测试值和模拟值吻合程度很好,该实验装置对透过装有遮阳系统的太阳辐射得热量的测试是可行的.同时通过测试结果发现,在上海地区11月上旬某典型日,特定的叶片角度下,采用遮阳系统后室内太阳辐射得热量可减少30%以上.     

吉祥草的耐阴性试验及在常德地区应用建议

吉祥草是一种优良的地被植物，在常德地区被大量应用，但在很多地方均生长不良，据分析与光照强度有关。选择800盆吉祥草进行遮荫试验，进行常规的养护管理，观察记录吉祥草的生长状况并做比较分析，连续进行2年试验。结果表明，吉祥草在透光率20％-30％状态下生长良好，园林绿化中可应用在疏林底下，或与其他耐阴地被植物和山石搭配为最佳。