Influence of variety on the within-plant distribution of cassava green spider mite (Acari: Tetranychidae), and leaf anatomical characteristics and chemical components in relation to varietal resistance

The within-plant distribution of the cassava green spider mite, Mononychellus tanajoa Bondar, and the anatomical characteristics and the chemical components relating to varietal resistance of cassava, were studied using 11 cassava genotypes with varying levels of resistance for two dry seasons and one wet season. The results show that M. tanajoa aggregates on the top leaves of cassava at low levels of resistance as compared with a more even within-plant distribution at higher levels of resistance. Thus, for accurate sampling of mite populations, it might be important to consider young and old leaves, not just the young leaves, in fields containing resistant and susceptible cassava genotypes. Correlations between the anatomical characteristics and mite population density and damage scores were not consistent across months, either within or over seasons. This suggests that leaf anatomical characteristics may not be important in the varietal resistance of cassava to M. tanajoa. During the dry season, mite population density was positively correlated with leaf nitrogen, potassium and phosphorus and negatively correlated with leaf calcium and fat. Only calcium was negatively associated with mite damage at the peak of the dry season (January 1993 and 1994). Breeding cassava genotypes with high levels of leaf calcium and fat, and low levels of leaf nitrogen, potassium and phosphorus, may improve the level of resistance to M. tanajoa.     

木薯渣与甜菜颗粒粕组合效应对奶牛瘤胃发酵特性的影响

本试验旨在通过体外产气法研究木薯渣与甜菜颗粒粕组合用作泌乳中后期奶牛饲料的可行性及适宜组合比例.试验设计7个处理:木薯渣分别以0％(对照组)、5％、10％、15％、20％、25％和30％与甜菜颗粒粕(风干物质基础)组合,使用AGRS-ⅡI型微生物发酵产气系统进行体外瘤胃微生物发酵试验,监测体外培养3、6、12、24、4...     

木薯渣作为饲料资源的开发与利用

木薯渣是木薯加工过程中产生的下脚料,富含大量盼纤维和淀粉。近年来,木薯渣作为饲料资源进行开发和利用能够使其变废为宝。减少对环境的破坏,受到了国内外的普遍重视。其中微生物发酵处理能够使木薯渣的粗纤维降解,改善适口性,提高饲料转化率。本文就木薯渣的营养特点、加工处理和在畜禽养殖中的应用等作一概括和总结。     

Prospects of polyploidizing cassava, Manihot esculenta Crantz, by unreduced microspores

Eleven interspecific hybrids of cassava with the wild relatives Manihot glaziovii, M. pseudoglaziovii. M. dichotoma and M. anomala were examined to detect unreduced microspores. The frequency of dyads and triads was counted, as well as pollen viability. Of these hybrids, the second generation progeny of cassava×M. glaziovii showed a high frequency of unreduced microspores (3.7%) permitting their selection for further manipulation of this character. An association of vegetatively-reproduced genotypes and the occurrence of unreduced microspores has also been observed.     

Effect of Nutrient Type on Chemical Composition and Dry Matter Partitioning of Cassava （Manihot esculenta Crantz）

The objective of our study was to determine the effects of four types of fertilisers enrichments （manure potassic （K）, phosphatic （P）, phosphatic and potassic （PK） and nitrogenized, phosphated and potassic （NPK）） on chemical composition and dry matter in cassava （Manihot esculenta） organs （clone 1171） during harvest period. The pots experiment was laid out in randomised complete bloc design with five treatments and four replications. Water, nitrogen, potassium, phosphorus, sodium, total proteins and total lipids contents of the leaves, shoots and tubers were determined. After 9 months growing period, results showed that fertilizer types enriched with K, PK and NPK significantly increased the organic compounds contents of the leaves （P〈0.05）. Furthermore, fertilizers with high phosphorus content significantly increased the lipid contents of the leaves （25%）. Fertilizers enriched with NPK positively influenced the biomass partitioning in Manihot esculenta. Application of fertilizers enriched with NPK led to higher levels of total proteins in the leaves and tubers （70 mg g DM^-1 and 30 mg g DM^-1 respectively） compared to control （17 mg g DM^-1 and 9 mg g DM^-1 respectively）. These results help to demonstrate the value of these fertilizers enrichment to improve the chemical composition and dry matter partitioning of cassava.     

种植密度和施氮水平对华南8号木薯产量形成的影响

探讨不同种植密度和施氮水平条件下华南8号木薯干物质积累、分配的规律及其对产量形成的影响。结果表明,低密度低施氮水平处理的产量显著高于高密度高施氮水平处理;低密度低施氮水平处理的单条薯重显著高于高密度高施氮水平处理,并且交互作用显著;低密度和低施氮水平处理虽然前期干物质生产速率较低,但后期干物质生产速率及其向块根的分配比例明显高于高密度和高施氮水平。     

木薯(Manihot esculenta)AKT1基因的克隆及生物信息学分析

植物细胞中的K^+通道蛋白AKT1(Arabidopsis K^+transpoter 1)主要负责吸收K^+。本研究基于木薯基因组数据库信息,利用PCR技术从木薯中克隆一个MeAKT1基因,该基因全长2634 bp,编码877个氨基酸,生物信息学分析表明MeAKT1含有10个外显子和9个内含子,编码的氨基酸分子量为99.02 kD,等电点为8.43,属于稳定蛋白。MeAKT1包含有5个跨膜区域,N端含有1个Ion_trans结构域,C端有1个KHA结构域,其二级结构以α-螺旋和无规则卷曲为主,进化树分析发现MeAKT1与蓖麻RcAKT1的亲缘关系最近。通过对MeAKT1蛋白的生物信息学分析有助于下一步深入研究MeAKT1在木薯耐贫瘠过程中的功能。     

芋优异种质资源鉴定评价研究

对农业行业标准《农作物种质资源鉴定评价规范芋》编制的技术路线进行了分析研究,以期为芋优异种质资源的鉴定评价提供参考。     

木薯渣发酵饲料及其发酵工艺与应用

文章旨在研究木薯渣发酵饲料及其发酵工艺与应用.将木薯渣、玉米面、豆粕、玉米皮、麸皮按照质量比50:5:10:10:25的比例混合,然后将乳酸菌和酵母菌按比例与一定量的水混合,再与木薯渣饲料混匀,装入带有呼吸阀的发酵袋中,密封,室温条件下发酵4 d即生产得到木薯渣发酵饲料.结果表明:乳酸菌和酵母菌混合比例为1:2,接种量...     

基于稳定同位素的江苏近海金乌贼摄食生态研究

为进一步掌握江苏近海金乌贼(Sepia esculenta)种群生活史特征，根据在江苏沿海港口所采集的样本，利用碳氮稳定同位素分析法对金乌贼的摄食生态及营养生态位进行了研究。结果表明，金乌贼雌、雄群体间 13C和 15N值均不存在显著性差异；金乌贼的 值与胴长之间相关性不显著， 值与胴长之间存在显著相关性；雄性金乌贼营养生态位宽度（SEAc=0.57‰2）与雌性（SEAc=0.63‰2）无明显差异，雌性略大于雄性，且两者高度重叠（0.62）。同位素聚类分析显示，可将金乌贼个体分为75~114mm、115~184mm和185~204mm三个胴长组；185~204mm胴长组营养生态位宽度最大（SEAc=1.77‰2），75~114mm胴长组营养生态位宽度最小（SEAc=0.39‰2）；仅75~114mm和115~184mm胴长组间生态位重叠率为中度重叠（0.34），其余胴长组间生态位重叠率低。分析认为，金乌贼δ13C值的变化主要受同位素基线值和金乌贼洄游模式影响，而δ15N值的变化主要受金乌贼摄食作用影响；雌性和雄性金乌贼群体之间食物资源和栖息地利用高度相似；不同发育阶段的金乌贼在营养生态位上具有明显差异。