过量施氮对嵌合体‘金旗’玉簪叶色、氮代谢关键酶活性及叶绿体超微结构的影响

以嵌合体类型花叶玉簪的代表品种‘金旗’玉簪为材料,研究了过量施用氮肥对嵌合体‘金旗,玉簪叶片的不同部位叶色变化、氮代谢关键酶以及叶绿体超微结构的影响.研究结果显示,在过量(2 g/kg栽培基质)尿素处理后28 d,嵌合体‘金旗’玉簪叶片黄色部位完全转绿,叶绿素含量显著上升且达到最大值;与其相对应嵌合体‘金旗,玉簪叶片的...     

Rights,Resources and Rural Development: Community-Based Natural Resource Management in Southern Africa — Christo Fabricius,Eddie Koch,Hector Magome and Stephen Turner (eds) 2004

Goats select some browse species more than others, given options. Seasonal trends of diet selection of Nguni goats indexed by intake were investigated in cafeteria-style experiments. The relationships between diet selection and plant chemical/physical traits of Vachellia nilotica, Vachellia robusta, Dichrostachys cinerea, Euclea crispa, Rhus lancea and Ziziphus mucronata, representing abundant species were studied in the dry and rainy seasons. Seasonal changes in browses affected diet selection. Selection of long shoot species, which were concomitantly broad-leafed, was higher than species with short shoots. Selection was higher for spineless than spinescent species. Diet selection correlated positively with increased leaf mass. In the rainy season, cellulose positively correlated with intake, number of bites and browsing time, whereas in the dry season, cellulose correlated with bite size. Diet selection tended to be driven more by shoot morphology and leaf mass than by either spinescence or plant chemistry. Plant chemical influence on diet selection was diverse in both seasons and showed no definite trend, whereas spinescence had no significant effect on short-term intake. The results represent important input to goat production and range forage species management.     

6种高丛蓝莓叶片形态解剖特征的比较研究

以辽南地区引种的6个高丛蓝莓品种为试验材料,通过叶片扫描、“指甲油印迹法”和石蜡切片法对比研究了各品种叶片形态解剖特征。结果表明：北高品种叶片的分形维数高于南高,大粒蓝金最大,库帕最小,但北高品种叶厚小于南高;南高品种气孔大于北高,而气孔密度小于北高品种,品种间气孔形状无明显差异;气孔分布随观察视野的变大皆呈均匀分布到随机分布,北高品种先于南高变为随机分布;南高品种表皮细胞、栅栏组织、海绵组织厚度大于北高,角质层和中脉厚度南北差异较小,但北高品种的中脉与叶片厚度之比高于南高品种;叶片组织紧密度、疏松度和栅海比南北两大种植品系之间无规律性变异,品种之间却存在显著差异。     

43个柑橘品种（品系/株系）受枸橘潜叶甲为害程度调查研究

采取随机抽样法,调查枸橘潜叶甲对枳、柚、柑、桔、甜橙、枸椽、杂柑及金柑等8大类共43个品种（品系/株系）为害虫情指数,其结果表明,不同柑橘种类或不同柑橘品种或品系均可受枸橘潜叶甲为害,但为害的程度存在着差异性,枳、柚受害最重,金柑、桔、杂柑类受害最轻,对其差异产生的原因亦作了初步分析。     

Influences of Northern Leaf Blight on corn silage fermentation quality,nutritive value and feed intake by sheep

This study examined the differences between non‐inoculated (control) corn and Northern Leaf Blight (NLB)‐damaged corn (inoculated corn); dry matter (DM) yield, silage fermentation quality, nutritive value and feed intake by sheep were compared. Leaf, stem and grain dry weights and gross yield of inoculated corn were significantly (P < 0.05) decreased compared with control corn. The contents of water‐soluble carbohydrate and nitrogen‐free extract (NFE) were decreased in inoculated corn compared with control corn. Silage made from both inoculated and control corn showed good fermentation quality. The digestibility of DM, organic matter, ether extract, NFE, and energy of silage made from inoculated corn were significantly (P < 0.05) lower, and contents of total digestible nutrients (TDN) and digestible energy (DE) were also significantly (P < 0.05) lower compared with silage made from the control corn. DM intake showed no significant discrepancy between the two types of silage. TDN and DE intakes from inoculated silage were significantly (P < 0.05) lower compared with control silage. From the above results it was shown that NLB caused a decrease in DM yield and NFE content in corn and a decrease in the nutritive value and feed intake of silage.     

野生老芒麦种质资源鉴定与基部叶鞘绒毛变异分析

为更好地利用老芒麦(Elymus sibiricus L.)野生资源,本研究从我国青藏高原、西北、华北、东北地区以及国外部分地区共采集了1 723份野生披碱草属种质资源,通过表型特征观测和流式细胞仪检测,共鉴定出了990份野生老芒麦种质,246份垂穗披碱草种质,并测得老芒麦的DNA含量在5.86～7.30 Gb之间,平均DNA含量为6.66 Gb;垂穗披碱草材料的DNA含量在9.50～10.36 Gb之间,平均DNA含量为9.97 Gb。研究结果显示,在西北、华北以及东北地区的部分野生老芒麦材料在苗期基部叶鞘出现了绒毛,分析发现该表型出现的概率与经度和纬度呈极显著正相关关系(P<0.01),与海拔、年年均气温以及年平均降雨量呈极显著负相关关系(P<0.01)。表明老芒麦苗期基部叶鞘绒毛的有无与环境因子之间存在着必然的联系,可能是老芒麦种质应对不同环境类型的适应性机制之一。本研究为老芒麦的形态鉴定提供了新的依据,为老芒麦种质资源挖掘和育种应用提供了材料基础。     

土壤干旱胁迫对玉米叶片水分状况、膜透性及酶抗氧化系统的影响

A simulation experiment on the responses of maize （Zea mays L.） from the third leaf stage to maturity for different soil water levels （well-watered, moderately stressed, and severely stressed） was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with wellwatered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content （RWC） and did change significantly the relative conductivity （RC） （P 〈 0.05） of the leaves; however, severe stress did significantly decrease （P 〈 0.01） the leaf RWC and increase （P 〈 0.01） membrane permeability （leaf relative conductivity）. Furthermore, under severe drought stress antioxidant enzyme activities declined significantly （P 〈 0.01） in later stages, namely for superoxide dismutase （SOD） the tasseling and blister stages, for peroxidase （POD） the milk stage, and for catalase （CAT） during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation （measured as malondialdehyde content） significantly increased （P 〈 0.01） in all stages.     

Determination of critical nitrogen dilution curve based on leaf area index for winter wheat in the Guanzhong Plain,Northwest China

Excessive use of nitrogen(N) fertilizers in agricultural systems increases the cost of production and risk of environmental pollution. Therefore, determination of optimum N requirements for plant growth is necessary. Previous studies mostly established critical N dilution curves based on aboveground dry matter(DM) or leaf dry matter(LDM) and stem dry matter(SDM), to diagnose the N nutrition status of the whole plant. As these methods are time consuming, we investigated the more rapidly determined leaf area index(LAI) method to establish the critical nitrogen(N_c) dilution curve, and the curve was used to diagnose plant N status for winter wheat in Guanzhong Plain in Northwest China. Field experiments were conducted using four N fertilization levels(0, 105, 210 and 315 kg ha-1) applied to six wheat cultivars in the 2013–2014 and 2014–2015 growing seasons. LAI, DM, plant N concentration(PNC) and grain yield were determined. Data points from four cultivars were used for establishing the N_c curve and data points from the remaining two cultivars were used for validating the curve. The N_c dilution curve was validated for N-limiting and non-N-limiting growth conditions and there was good agreement between estimated and observed values. The N nutrition index(NNI) ranged from 0.41 to 1.25 and the accumulated plant N deficit(N_(and)) ranged from 60.38 to –17.92 kg ha~(-1) during the growing season. The relative grain yield was significantly affected by NNI and was adequately described with a parabolic function. The N_c curve based on LAI can be adopted as an alternative and more rapid approach to diagnose plant N status to support N fertilization decisions during the vegetative growth of winter wheat in Guanzhong Plain in Northwest China.     

光照强度对冬小麦旗叶光合生理特性的影响

为建立冬小麦相应的光合作用模型提供数据支持,在20℃、不同光强梯度下,测定了冬小麦旗叶净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO2浓度(Ci)等生理指标,研究自然条件下抽穗期冬小麦旗叶光合生理特性的变化规律。结果表明,光合速率随光照强度增加而增加并呈正相关(p<0.05),在光强度低于500μmol/(m2.s)时,小麦旗叶的光合速率快速增加;气孔导度随光强增强而增强并呈正相关(p<0.05),但在光强度低于100μmol/(m2.s)时气孔导度增幅很小;蒸腾速率随光强度的变化与光合速率趋势基本一致;胞间CO2浓度随光强度的增加呈先降低后增加趋势。     

蔗叶机械化粉碎还田负面效应分析与控制

通过对甘蔗叶粉碎还田前后土壤结构、营养成分以及还田技术方式进行分析和试验对比,初步探讨其主要原因,并提出了从种植、管理、技术手段等多方面相结合的控制技术措施。