松嫩平原寸草苔种群生殖分株的种子生产与生殖分配策略

在松嫩平原 ,寸草苔种群生殖分株种子生产数量 ,在休闲放牧场为 (15.2 5± 2 .78)粒 /穗 ,在割草场为 (11.4 4± 2 .2 4 )粒 /穗。籽粒千粒重休闲放牧场为 (1.5873± 0 .10 54) g ,割草场为 (1.4 6 4 6± 0 .2 333)g。生殖分株的生物量及其穗与籽粒各组分重量均为随着高度级的增加呈规律性增加 ,但穗重占全株重比率的生殖分配Ⅰ和籽实重占全株重比率的生殖分配Ⅱ均随着高度级的增加呈直线形式减少。不同生长状况的生殖分株对有限资源具有不同的分配策略。     

Modelling the concentrations of nitrogen and water-soluble carbohydrates in grass herbage ingested by cattle under strip-grazing management

There is scope of increasing the nitrogen (N) efficiency of grazing cattle through manipulation of the energy and N concentrations in the herbage ingested. Because of asymmetric grazing by cattle between individual plant parts, it has not yet been established how this translates into the concentrations of N and water‐soluble carbohydrates (WSC) in the herbage ingested. A model is described with the objective of assessing the efficacy of individual tools in grassland management in manipulating the WSC and N concentrations of the herbage ingested by cattle under strip‐grazing management throughout the growing season. The model was calibrated and independently evaluated for early (April), mid‐ (June, regrowth phase) and late (September) parts of the growing season. There was a high correlation between predicted and observed WSC concentrations in the ingested herbage (R² = 0·78, P < 0·001). The correlation between predicted and observed neutral‐detergent fibre (NDF) concentrations in the ingested herbage was lower (R² = 0·49, P < 0·05) with a small absolute bias. Differences in the N concentration between laminae and sheaths, and between clean patches and fouled patches, were adequately simulated and it was concluded that the model could be used to assess the efficacy of grassland management tools for manipulating the WSC and N concentrations in the ingested herbage. Model application showed that reduced rates of application of N fertilizer and longer rotation lengths were effective tools for manipulating herbage quality in early and mid‐season. During the later part of the growing season, the large proportion of area affected by dung and urine reduced the effect of application rate of N fertilizer on herbage quality. In contrast, relative differences between high‐sugar and low‐sugar cultivars of perennial ryegrass were largest during this period. This suggests that high‐sugar cultivars may be an important tool in increasing N efficiency by cattle when risks of N losses to water bodies are largest. The model output showed that defoliation height affects the chemical composition of the ingested herbage of both the current and the subsequent grazing period.     

短花针茅草地几种牧草利用率的确定

在短花针茅荒漠草原，利用高度一重量百分比方法确定了13种牧草的利用率。结果表明：对于大多数牧草消耗高度占总高度的50%，重量的消耗仅20%～30%；当牧草消耗高度80%时，牧草的利用率为70%。在利用率确定的情况下，可推导出各种牧草的适宜留茬高度。     

棉花品种的群体株高对种子产量影响的研究

品种与密度互作产量之间有显著差异,最能反映品种特征特性的是株型,反映株型的最好指标是株高。在一定生产水平和群体容量范围内,株高与密度呈明显的反相关。品种的群体株高不仅表现直观平面的量化指标(cm),同时可透视动态的立体内涵指标——果枝果节,两者对棉种产量的合理建成具有重要的影响。该文从950块3730公顷棉种繁殖田中随机任择100块,调查群体株高交叉配合的效应,探讨不同群体株高的配合适度及其最佳运筹点,以聚类和回归分析的方法加以验证。研究结果对大面积棉种高产、稳产、优质、高效繁殖具有切实可行的参考价值。     

Prolonged elevated atmospheric CO2 does not affect decomposition of plant material

Prolonged elevated atmospheric CO₂ might alter decomposition. In a 90-day incubation study, we determined the long-term (9 years) impact of elevated CO₂ on N mineralization of Lolium perenne and Trifolium repens plant material grown at ambient and elevated CO₂ and low- and high-¹⁵N fertilizer additions. No significant differences were observed in recovery rates between any of the treatments, except an N addition effect was observed for L. perenne (0.4 versus 0.5% day⁻¹ in high versus low N). The results suggest that elevated CO₂ did not change plant N mineralization in any of the soils, because of a surplus of available N in the fertilized and leguminous systems, and because of insignificant plant responses to elevated CO₂ in the low soil N availability systems.     

作物株型相关基因研究进展

概述了作物株型的概念及决定作物株型的主要性状如株高、分蘖数、分蘖角度等方面的研究进展,提出:矮化基因的研究是当前株型育种的主要方向,并对基因工程在改进株型中的广阔应用前景进行了阐述。     

不同基质对耧斗菜幼苗质量的影响

耧斗菜属多年生宿根花卉,花型奇特,花色鲜艳、丰富,具有很高的观赏价值,可大量应用于园林中。试验研究不同基质配比对耧斗菜组培苗苗期的株高、株幅、叶片数的影响。结果表明,处理A(V(珍珠岩)∶V(草炭)∶V(园土)=8∶1∶1)的基质配比对耧斗菜的株高、株幅影响较大,植株生长状况最佳。随着珍珠岩量的减少及园土量的增加,植株生长状况减弱。     

头枕高度对侧卧睡眠舒适性的影响

通过人体侧卧时头部及颈肩部压力分布测试、舒适感主观评价及相关性分析,以及人体胸颈部脊柱定位点分析和肩颧距测量等方法,研究承重后头枕高度变化对人体睡眠舒适性变化的影响。结果发现:侧卧人群宜选择承重后高度7～8cm的睡枕;枕高5cm时,脊柱上部呈"凸"字形状,枕高14cm时,脊柱上部呈"\"字形状;肩颧距与舒适枕高值存在较高的正相关性,最佳枕高值小于肩颧距。该结果可为侧卧枕高的个性化设计提供依据。     

蚯蚓堆肥处理剩余污泥混合有机垃圾的效率研究

为了研究基质堆料高度和高密度接种条件对蚯蚓堆肥处理有机垃圾混合剩余污泥时蚯蚓生物量及其堆肥效率的影响,共设6个处理进行试验,按接种密度-堆料高度表示,分别为:1/10-10cm组、1/10-15cm组、1/15-10cm组、1/15-15cm组、1/20-10cm组、1/20-15cm组。试验结果表明,在堆料高度相同时,蚯蚓生物量与其接种密度呈显著的负相关关系,但接种密度对蚯蚓堆肥效率的影响有限,只有在1/10组同1/15组或1/20组比较时表现出显著差异,而后两个组别之间差异不显著;在接种密度相同时,堆料高度对蚯蚓堆肥效率的影响不显著,而对蚯蚓生物量的影响可能存在一个密度临界点(1/15),在此密度附近,堆料高度对蚯蚓生物量的影响较显著,呈显著正相关关系,而在此密度以上或以下,堆料高度的影响不显著。从产业应用的角度,综合考虑蚯蚓维持种群繁衍的再生产能力以及混合污泥的堆肥效率这两个因素,赤子爱胜蚓(Eisenia foetida)处理有机垃圾混合剩余污泥的最佳接种密度为1/15,堆料高度为15cm。