凋落叶多样性对杉木凋落叶分解的影响

为促进杉木凋落叶分解,采用网袋法对杉木凋落叶多样性模式的失重率、种间相互作用和分解速率与初始质量的关系进行分析。结果表明：经过1 a的分解,除MS和SN 2组处理,其他处理的分解速率均大于杉木凋落叶。通过多样性处理,对凋落叶分解均有促进作用,尤其是SHN、SHR和SRN 3组处理,对杉木凋落叶分解具有一定作用,其中SHN、SHR、SRN和SHRN凋落叶多样性处理较其他处理能更好地促进杉木凋落叶分解,SHRNM凋落叶多样性处理则抑制杉木凋落叶分解。相关性检验表明,凋落叶的分解速率与初始纤维素含量达到极显著的正相关水平;与C含量和木质素含量及木质素/N具有极显著的负相关性,与C/N、C/K和木质素/K具有显著的负相关性。     

被子植物花粉和雌蕊互作的分子基础

被子植物的花粉自落到柱头上开始, 花粉和雌蕊组织即发生一系列的相互识别作用, 这个过程包括花粉与柱头互作、花粉管极性生长和引导、精细胞在胚囊中释放和完成双受精。近年来, 已相继发现并且克隆了花粉与柱头互作以及花粉管生长和引导相关的基因。本文对花粉粘附、水合、萌发以及花粉管生长和引导的分子机制进行了综述, 重点讨论了花粉粘附的糖蛋白互作、花粉水合的脂类调控途径以及花粉管极性生长的阿拉伯半乳聚糖蛋白等小分子引导机制, 以期为被子植物的繁殖生物学研究提供理论依据。     

密度氮肥交互处理下高寒地区燕麦的生长特性与生殖分配

基于盆栽试验,设置9个不同密度、不同施氮量的交互处理,研究了高寒地区燕麦(Avena sativa)的生长特性、生殖分配格局对不同密度和氮肥交互处理的响应。结果表明,1)同等密度水平下,随着氮肥量的增加,燕麦高度、叶长、穗长、分蘖数及各器官生物量显著增加,且高氮肥(2 g·盆-1)处理下也极显著(P0.01)大于其他处理,施氮肥促进了燕麦植株生长,光合作用功能增强,分蘖数增加,营养物质的制造和积累增加。同等氮肥水平下,大部分性状随密度增加而减小,表现出竞争作用。不同密度、不同施氮量对叶长和生殖生物量的交互作用不显著(P0.05)。2)密度和氮肥交互作用下,燕麦的各生长指标之间均为极显著正相关。3)生殖生物量分配在高密度(50粒·盆-1)×中氮肥(1 g·盆-1)(HD×MF)交互处理下达到最大值(12.23%),与已有的一年生植物生殖分配比例高于20%的结论不一致。4)燕麦各器官的资源分配方面都存在“此消彼长”的权衡关系。     

Soil quality and fertility in sustainable agriculture,with a contribution to the biological classification of agricultural soils

Soils and crops are particularly vulnerable to climate change and environmental stresses. In many agrosystems, soil biodiversity and ecosystem services provided by soils are under threat from a range of natural and human drivers. Agricultural soils are often subject to agronomic practices that disrupt soil trophic networks and make soils less productive in the long term. In this scenario, sustainable soil use aimed at improving plant/root status, growth and development plays a crucial role for enhancing the biological capacity of agricultural soils. This commentary paper is divided into the following four main sections: (i) the contentious nature of soil organic matter; (ii) soil biological quality/fertility; (iii) soil classification; and, (iv) which agricultural practices can be defined as sustainable? The published literature was analyzed within a holistic framework, with agrosystems considered as living systems where soil, vegetation, fauna and microorganisms co-evolve and are reciprocally influenced. Ultimately, this article will suggest a better stewardship of agricultural soils as a natural capital.     

Factors that enhance or hinder social cohesion in urban greenspaces: A literature review

Urban greenspaces--including city parks, forests, and gardens--can provide many benefits that impact human wellbeing. One such aspect of wellbeing is social cohesion, which is broadly defined as the combined reasons to stay in a particular community. Although there is an increase in studies connecting human wellbeing, social cohesion, and urban greenspace, there is limited synthesis of the three concepts. The purpose of this paper is to review how social cohesion has been used, defined, and measured in the scholarly literature. In addition, we assess the factors that hinder or enhance social cohesion in urban greenspace and opportunities for future research. We conducted a systematic literature review using the PRISMA procedures. After doing a search with keywords, we read the abstracts of 1129 articles and selected 113 that met our inclusion criteria for final in-depth analysis. We provide an overview and conceptual diagram of the factors that enhance or hinder social cohesion in urban greenspaces. Although all of the analyzed articles included social cohesion as a variable or topic of interest, only 17 of those articles clearly defined and measured social cohesion. The most impactful ways to enhance social cohesion include reducing crime, improving maintenance, and having physical space and amenities for social gatherings that cater to various demographics. Likewise, studies suggest that the perceptions of safety, level of maintenance, accessibility, and efforts to be inclusive of diverse users including cultural activities and community engagement spaces were important to social cohesion. Overall, more research is needed to better understand social cohesion and urban greenspace in developing countries, and more in-depth analysis from the perspective of diverse urban residents who use these greenspaces. The results of this study have implications for designing and managing urban greenspaces to enhance social cohesion, inclusion, and overall human wellbeing.     

A systematic review of southern rice black-streaked dwarf virus in the age of omics

Southern rice black-streaked dwarf virus (SRBSDV) is one of the most damaging rice viruses. The virus decreases rice quality and yield, and poses a serious threat to food security. From this perspective, this review performed a survey of published studies in recent years to understand the current status of SRBSDV and white-backed planthopper (WBPH, Sogatella furcifera) transmission processes in rice. Recent studies have shown that the interactions between viral virulence proteins and rice susceptibility factors shape the transmission of SRBSDV. Moreover, the transmission of SRBSDV is influenced by the interactions between viral virulence proteins and S. furcifera susceptibility factors. This review focused on the molecular mechanisms of key genes or proteins associated with SRBSDV infection in rice via the S. furcifera vector, and the host defense response mechanisms against viral infection. A sustainable control strategy using RNAi was summarized to address this pest. Finally, we also present a model for screening anti-SRBSDV inhibitors using viral proteins as targets. © 2023 Society of Chemical Industry.     

Perspectives of the Fritz-Scheffer Awardee 2021: Profile- to ecosystem-scale perspectives on soil organic matter formation as demonstrated by woody debris in forest dynamics

Soil organic matter (SOM) forms along a continuum from individual particles, pores, and aggregates to litter–soil profiles and larger ecosystems such as forests. However, forest management of SOM stocks and the carbon therein requires knowledge on which processes and factors at which scales determine SOM formation from forest biomass. As evident from woody debris at the profile scale, SOM forms through additions, transformations, translocations, and removals of litter by soil organisms and environmental components. Yet SOM stocks only increase if litter additions-to-removals are out of steady state or enter a new steady state that ignores older litter. Both happen through disturbance and self-selecting feedback processes in ecosystems consisting of autotrophs, heterotrophs, and their physical environment. One such positive feedback process is litter-SOM transformation by heterotrophs that releases nutrients that promote plant productivity and thus litter input. Stocks of litter-SOM, heterotrophs, nutrients, and plants thus exhibit Lotka–Volterra dynamics (i.e., predator–prey interactions) and only increase when attractor states (i.e., steady series or sets of states) change due to disturbance. Evidence of evolving feedback processes and disturbance in SOM would help identify limits, potentials, and precariousness of ecosystems in light of global change, but remains to be found.