草本植物遮荫效应的研究进展

从遮荫对草本植物的生长环境、生理生化特性、形态解剖结构、营养分配及产量影响方面进行了综述.遮荫可明显改变草本植物的生长环境,进而对其生理生化特性及产量产生较大的影响.草本植物为适应荫蔽的环境,导致在光合作用单位、电子传递、光合色素含量、内源激素及酶活性、植株形态解剖结构、营养物质的吸收及分配等方面产生变化,以保证在遮荫下仍能充分利用光能,维持生长所需的能量平衡,进行正常的生命活动.     

Effect of green infrastructures supported by adaptative solar shading systems on livability in open spaces

Lack of thermal comfort in the existing building stock in many warm summer climates and the COVID-19 pandemic have increased residents' temporary occupation of urban open spaces. However, climate change and other effects such as urban heat islands are also negatively affecting the livability of these spaces. Therefore, strategies are needed to improve the thermal conditions in these areas. In this context, the research designs, simulates and assesses an urban green infrastructure supported by an adaptative solar shading system. For this purpose, a public square to be renovated in Seville (Spain) is chosen. After an analysis of the current situation, more vegetation is added. However, trees are not planted fully grown, so their cover is not enough in the short term and an artificial system that protects from the sun by casting shade and that adapts to both their growth and the seasons is included. The urban space is characterized by on-site measurements, proposing four (initial, intermediates and final) scenarios using computational fluid dynamics simulations in an holistic microclimate modelling system. In turn, changes in thermal comfort are analyzed using the COMFA model. Results show that the air and surface temperature are decreased, reducing the number of hours in discomfort by 21% thanks to incorporating the green structure and by 30% due to the vegetation. It can be concluded that the use of these temporary urban prostheses enables urban spaces regenerated with vegetation to be enjoyed without waiting 20 or 30 years for the trees to mature, encouraging people to spend more time outdoors from the start of the intervention.     

遮阴和露地栽培条件下蜘蛛香叶片的抗氧化酶比活力和丙二醛含量

研究旨在阐明蜘蛛香叶片酶类抗氧化能力在遮阴和露地栽培条件下的差异,为蜘蛛香应答阳生环境的研究和蜘蛛香大田栽培配套技术的制定提供参考。以滇中地区遮阴和露地栽培条件下的蜘蛛香叶片为试材,用分光光度法研究了叶片的可溶性蛋白质含量和抗氧化酶[（即：过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)]的比活力以及丙二醛(MDA)含量。与遮阴栽培相比,露地栽培会使蜘蛛香叶片的可溶性蛋白质含量降低了11.30%,但会使叶片CAT、POD和SOD比活力以及MDA含量分别升高了11.43%、30.90%、21.58%和18.48%;叶片可溶性蛋白质含量和CAT比活力在遮阴和露地条件下的差异均未达到显著水平,而POD和SOD比活力以及MDA含量的差异均达到显著水平。在露地栽培条件下,蜘蛛香叶片的可溶性蛋白质含量下降、细胞脂质的过氧化损伤加剧,但CAT、POD和SOD比活力会同时提高而强化叶片细胞的酶类抗氧化能力。     

Decreased panicle N application alleviates the negative effects of shading on rice grain yield and grain quality

Light deficiency is a growing abiotic stress in rice production. However, few studies focus on shading effects on grain yield and quality of rice in East China. It is also essential to investigate proper nitrogen (N) application strategies that can effectively alleviate the negative impacts of light deficiency on grain yield and quality in rice. A two-year field experiment was conducted to explore the effects of shading (non-shading and shading from heading to maturity) and panicle N application (N_DP, decreased panicle N rate; N_MP, medium panicle N rate; N_IP, increased panicle N rate) treatments on rice yield- and quality-related characteristics. Compared with non-shading, shading resulted in a 9.5–14.8% yield loss (P<0.05), mainly due to lower filled-grain percentage and grain weight. N_MP and N_IP had higher (P<0.05) grain yield than N_DP under non-shading, and no significant difference was observed in rice grain yield among N_DP, N_MP, and N_IP under shading. Compared with N_MP and N_IP, N_DP achieved less yield loss under shading because of the increased filled-grain percentage and grain weight. Shading reduced leaf photosynthetic rate after heading, as well as shoot biomass weight at maturity, shoot biomass accumulation from heading to maturity, and nonstructural carbohydrate (NSC) content in the stem at maturity (P<0.05). The harvest index and NSC remobilization reserve of N_DP were increased under shading. Shading decreased (P<0.05) percentages of brown rice, milled rice, head rice, and amylose content while increasing (P<0.05) chalky rice percentage, chalky area, chalky degree, and grain protein. N_MP demonstrated a better milling quality under non-shading, while N_DP demonstrated under shading. N_DP exhibited both lower chalky rice percentage, chalky area, and chalky degree under non-shading and shading, compared with N_MP and N_IP. N_DP under shading decreased amylose content and breakdown but increased grain protein content and setback, contributing to similar overall palatability to non-shading. Our results suggested severe grain yield and quality penalty of rice when subjected to shading after heading. N_DP improved NSC remobilization, harvest index, and sink-filling efficiency and alleviated yield loss under shading. Besides, N_DP would maintain rice’s milling, appearance, and cooking and eating qualities under shading. Proper N management with a decreased panicle N rate could be adopted to mitigate the negative effects of shading on rice grain yield and quality.     

遮阴对‘佛手’茶树生长及品质的影响

为解决夏暑茶叶苦涩感强、综合品质差等问题,设置80%、60%、50%遮阴和未遮阴4个处理,其中未遮阴为对照,分析不同遮阴处理下‘佛手’茶树新梢农艺性状、新梢内含成分及成茶感官品质。研究发现,遮阴处理可使新梢叶色变绿、叶质变软,叶面积增大5.25~8.17 cm²,百芽重增加32.04~60.32 g、新梢含水量增加1.27~3.94个百分点;使新梢叶绿素a、叶绿素b、总叶绿素、水浸出物、咖啡碱、氨基酸含量分别提高0.61~0.95、0.29~0.6、0.9~1.55、1.21~4.37、0.13~0.45、0.66~1.14个百分点;茶多酚含量、酚氨比、叶绿素a/b分别下降3.73~5.5个百分点、5.77~8.1、0.22~0.58;成茶感官品质评分增加5.55~16.4分。遮阴可明显促进‘佛手’茶树生长,改善新梢生化品质及感官品质,其中以80%遮阴综合改善效果最佳,感官评分达91.75。     

遮阳对树番茄幼苗叶片性状及化学计量特征的影响

以一年生树番茄(Cyphomandra betacea Sendt.)幼苗为研究对象，设置4种光照(100%、75%、50%、25%自然光照)，测定树番茄幼苗叶片性状以及C、N、P、K含量，分析各指标之间的差异性。结果表明：叶宽、叶面积、叶片含水率、比叶面积在50%自然光照下最大；全光照处理下，树番茄幼苗叶片C含量大于其他遮阳处理的；遮阳处理下，叶片N、P、K的含量大于茎、粗根和细根的；除粗根外，树番茄幼苗各器官的K含量随遮阳程度的增加而不断增加；树番茄幼苗叶片的氮磷比随遮阳程度的增加不断增加；叶、细根的碳氮比和碳磷比小于茎和粗根的，而茎的氮磷比、氮钾比小于叶、粗根和细根的；遮阳处理下，树番茄生长受N、P限制，不受K限制；树番茄幼苗主要通过改变叶片的N、P含量以及茎的N含量、粗根的K含量来适应光照变化。室外栽培、林下种植以及园林应用中可选择50%遮阳环境，并适量施用N、P肥。