侵蚀土壤物理性质变化及其与土壤氮素迁移转化的关系

侵蚀破坏土壤团聚体结构,使团聚体破碎产生更小的可迁移颗粒而导致土壤养分的运移;侵蚀还改变了土壤的水分状况,水蚀在一定程度上增加了土壤的含水量,风蚀则可使土壤的含水量降低。团聚体结构的破坏以及土壤水分状况的改变与土壤的氮素迁移转化过程有着密切的联系。本文仅对土壤侵蚀造成的土壤物理性状的改变与土壤氮素迁移转化作一概述,并就耕作、覆盖等降低土壤侵蚀的农业措施与土壤氮素转化的关系进行阐述,提出了侵蚀土壤氮素研究的去向。     

抑制无效分蘖对不同基因型水稻根系特征及养分吸收的影响

为了研究抑制无效分蘖对不同基因型水稻根系特征及养分吸收积累的影响,以培杂泰丰和粤晶丝苗为材料(分别记为P和Y),通过设计不同的栽插孔穴直径(栽插孔径分别为20,28,35 mm,依次记为D1、D2、D3)限制水稻的无效分蘖,试验采用水培法。结果表明:与D1、D3相比,D2显著提高了水稻培杂泰丰和粤晶丝苗的穗粒数和产量;在幼穗分化期,D2处理水稻培杂泰丰和粤晶丝苗根系根长、根表面积、根系体积以及根尖数和分叉数均明显高于D1处理;D2与D3处理培杂泰丰水稻抽穗期茎鞘P、K含量显著高于D1处理;D2处理抽穗期的钾素积累总量显著高于D1、D3处理;D3处理水稻粤晶丝苗幼穗分化期、抽穗期的氮素积累总量、磷素积累总量和钾素积累总量均显著高于D1处理。相关分析结果也表明,水稻齐穗期的总根长与氮素积累总量和钾素积累总量存在显著的正相关关系,根系的表面积和总体积与氮素、磷素和钾素积累总量均存在显著或极显著的正相关关系,而且,根系的平均直径与磷素积累总量和钾素积累总量也显著正相关。     

物理新技术处理种子方法的研究

物理新技术处理种子,旨在改善作物种子特性,实现增产。综合国内外已采用光、电、磁、声、微波等单因素处理种子的实例,均表明有一定增产效果。实践亦表明,采用合理的光加磁、微波加γ射线等多因素组合处理种子效果将优于单因素处理。通过物理技术处理种子的电磁、压力波、热、光效应等机理分析以及存在的问题,提出采用新型、有发展前途的仿生频谱处理种子技术。     

Improving quality of composted biowaste to enhance disease suppressiveness of compost-amended, peat-based potting mixes

Biowaste can be converted into compost by composting or by a combination of anaerobic digestion and composting. Currently, waste management systems are primarily focused on the increase of the turnover rate of waste streams whereas optimisation of product quality receives less attention. This results in low quality composts that can only be sold on bulk markets at low prices. A new market for quality compost could be potting mixes for horticultural container-grown crops to partially replace non-renewable peat and increase the disease suppressiveness of potting mixes. We report here on the effect of wetsieving biowaste prior to composting on compost quality and on disease suppressiveness against the plant pathogen Pythium ultimum of peat mixes amended with this compost. The increased organic matter and decreased salt content of the compost allow for significantly higher substitution rates of peat by compost. In this study up to 60% v/v compost peat replacement did not affect cucumber growth. However, disease suppressiveness of the potting mixes strongly increased from 31 to 94% when the compost amendment rate was increased from 20 to 60%. It was shown that general disease suppression for P. ultimum can only be effective when the basal respiration rate is sufficiently high to support microbial activity. In addition, organic matter of the compost should reach a sufficient stability level to turn from disease conducive to disease suppressive. Increasing the compost addition from 20 to 60% did not significantly affect plant yield, yield variation were due to differences in nutrient levels. It can be concluded that compost from wetsieved biowaste has high potential to replace peat in growing media for the professional market.     

猕猴桃对硒的吸收、分布、积累特性的研究

大田条件下,给中华猕猴桃施以浓度分别为0．15、0．3、0．5mg／培的Na：SeO,溶液,在盛花期每30d测定果实和叶对硒的积累情况;果实成熟期测定猕猴桃各部位含硒量以及鲜重、可溶性糖含量、可溶固形物和Vc含量;结果显示：施硒后,猕猴桃各部分含硒量显著升高,并且硒在猕猴桃中累计顺序为根〉叶〉花〉果实。果实鲜重、可溶性糖含量、可溶固形物和％含量随着硒浓度的增大而升高,然而在高浓度的硒（≥0．5rag／kg）水平下,受到不同程度的抑制。施硒显著提高了猕猴桃对硒的吸收、分布、积累和改善了果实的品质。     

Influence of tillage and crop residue on soil physical properties and yields of rice and wheat under shallow water table conditions

An experiment was conducted to evaluate the effects of tillage and residue incorporation on soil properties and yields of rice (Oryza sativa L.) and wheat (Triticum aestivum L.) in rotation for 4 years on a silty clay loam of an Aquic Hapludoll with natural water table fluctuating between 0.05 and 0.97 m depth The rice experiment was laid out in split plot design with four levels of tillage, viz. conventional puddling (CP), puddling by four passes of rotavator (PR), reduced puddling by two passes of rotavator (ReP), and direct seeding without puddling (DSWP) and two levels of residue, viz. residue incorporation (RI) and residue removal (RR) in four replications. The treatments for wheat were zero tillage (ZT) and conventional tillage (CT) with RI and RR superimposed over the plots of rice. Tillage for rice increased puddling index and bulk density (BD) over the years. The increase was significantly higher in CP and PR than in ReP. In wheat season, BD was higher under ZT than under CT but the differences were not significant. Puddling decreased saturated hydraulic conductivity with time, which became significantly lower in CP and PR in the fourth year than in ReP in the first year. Infiltration rate (IR) also decreased with time and was lowest in CP and PR. In wheat season, IR was at par under ZT and CT. Rice yield in PR was maximum and at par with that in ReP. But wheat yield was lowest in PR and highest in DSWP, and was at par in DSWP and ReP. Thus, rice yields were optimum under ReP, in which changes in soil properties were least, and wheat yields were optimum both under ZT and CT in the DSWP and ReP plots of rice under shallow water table conditions of the silty clay loam.     

贵州习水国家级自然保护区森林土壤理化性状研究

在贵州习水国家级自然保护区内,根据不同的森林植被分布状况及相应海拔高度设置了13个具有代表性的标准调查样地,分别采集土壤测定其理化性状,结果表明:(1)自然保护区森林土壤容重为1.07～2.06g/cm3;土壤总孔隙度为34.9%～83.4%;森林土壤的最大蓄水量为1479.00 t.hm-2～5517.00 t.hm-2;土壤的平均初渗速率和稳渗速率分别为9.05mm.min-1和3.32mm.min-1。(2)自然保护区森林土壤主要为酸性土壤,pH值在3.72～5.97之间变动;土壤有机质的含量为74.83g/kg;土壤全N和有效N分别为2.01g/kg和215.09mg/kg;土壤的全P含量为0.33g/kg;土壤速效磷含量在1.10～84.92mg/kg之间波动,平均含量为8.02mg/kg;土壤的全K和有效K含量分别为11.81g/kg和64.37mg/kg。(3)习水自然保护区所分布的森林植被类型在改良其森林土壤的物理特性,提高土壤的贮水能力,丰富土壤有机质及其N、P、K的含量,增强和维护土壤肥力等方面都具有较显著的生态功能。     

怀山药生长土壤的研究

采用野外调查与室内分析相结合的方法。研究了怀山药生长土壤的分布概况、类型、物理性质、化学性质等。不同土种,不同的理化特性,怀山药品质不同。砂壤土、小两合土、淤土、褐土化两合土4个土种中,以褐土化两合最适宜怀山药的生长,其在质地、土壤结构、砂粘比例、土壤耕性、养分状况等方面均为理想,所产怀山药产量高,品质佳。     

开花期和果枝部位对短季棉纤维品质及超分子结构的影响

 利用中棉所 16研究了开花期和果枝部位对棉纤维品质与棉纤维超分子结构各项参数动态变化的影响。研究表明 ,棉纤维长度、细度、成熟度及棉纤维强度等品质性状均随开花期推迟温度降低逐渐变差 ,相同开花期条件下果枝部位对棉纤维品质性状有一定影响 ,呈现出下部棉纤维品质略高于上部的趋势 ,但不显著。前期开花较早温度较高时下部果枝的超分子结构参数呈现出优于上部的趋势 ,与下部果枝的棉纤维品质略高于上部相一致 ,但果枝部位的影响并不能改变由于开花期推迟温度降低而对棉纤维超分子结构所产生的影响。     

土壤物理性与林木生长关系的研究

本文应用多元回归、逐步回归方法,研究土壤物理性与林木生长的关系.研究认为相关显著,不同成土母岩发育的土壤,对林木生长的相关性和影响生长差异的主导因子不同.花岗岩发育的土壤主导因子是容重、非毛管孔隙度和腐殖质层厚度,砂岩发育的土壤主导因子是土层厚度,非毛管孔隙度和腐殖质层厚度.在湿润的南岭山地,林木生长对非毛管孔隙度的要求比总孔隙度的相关更显著,同时要求两者比例适宜.