Effect of salt stress on the physiological and photosynthetic characteristics of Weigela florida

Effects of salt stress on the physiological and photosynthetic characteristics of Weigela florida were studied. The results showed that the leaf area of Weigela florida was enhanced at 0.1% and 0.2% salt concentration, but decreased obviously when salt concentration was higher than 0.3%. The symptom of the salt injury was not significant when the salt concentration was lower than 0.3%, but was significant when higher than 0.4%. The water content decreased gradually but the electrolyle leakage increased gradually with the increasing of salt concentration and time. The total content of chlorophyll was rising while salt concentration was lower than 0.3%, but decreased while salt concentration was higher than 0.4%. The proline contents increased gradually while salt concentration was lower than 0.5%, but decreased at 0.5%. The soluble sugar content increased gradually with the increasing of salt concentration and prolonging of treatment, but decreased at 0.4% salt concentration 15 days after salt treatment. To the photosynthetic characteristics, the salt concentrations of 0.1% and 0.2% did not affect the photosynthetic characteristics of Weigela florida, when salt concentration was higher than 0.3%, the salinity significantly reduced Pn, Gs and Tr, but enhanced intercellular CO₂ concentrations at the salt concentrations of 0.3% and 0.4%. It was indicated that 0.1% and 0.2% salt concentrations had little influence on Weigela florida. The growth of Weigela florida was slightly decreased at the salt concentration of 0.3% without effect on its normal growth. However, the salt concentration of 0.4% affected the growth of Weigela florida obviously. Weigela florida died 7 days after treatment and it could not normally grow when salt concentration is higher than 0.5%.     

辉河保护区草甸草原群落最小面积的确定

采用4种饱和曲线方程拟合群落种-面积曲线,对辉河保护区内草甸草原植物群落的最小面积进行了研究。研究结果表明:(1)S=c-ae~(-bA)模型的拟合的相关系数最大,拟合效果比其他三种模型的拟合效果好,且准确性高。采用该模型计算的草地植物群落最小面积与实际相符;(2)当比例因子P(0P1)取0.6,0.7,0.8时,植物群落的最小面积分别是391、678、1 084 m~2。样方设置为35 m×35 m大小的正方形时,可以满足包括植物群落总物种数的60%,70%,80%中等精度要求。当比例因子P取0.9时,求得群落最小面积是1 777 m~2(45 m×45 m),可以满足包括植物群落总物种数的90%的高等精度要求。     

耕层厚度对华北高产灌溉农田土壤有机碳储量的影响

针对华北平原长期少免耕可能导致的耕层变浅、变紧的问题,通过人为设置不同耕层厚度试验,采用等质量土壤有机碳库储量和层化比的研究方法,研究了4种耕层厚度（10、20、30、40 cm）水平下0～50 cm土壤有机碳的变化。2 a的田间试验结果表明,不同耕层厚度对土壤有机碳含量有显著差异,与2007年试验开始时相比,土壤有机碳质量分数都不同程度下降,下降幅度为22%～48%。利用等质量计算方法表明20 cm耕层厚度的处理土壤有机碳储量最高。通过层化比的研究表明,随着时间的推移,20 cm的耕层厚度层化比最高,其     

抗球虫药新剂型的制备与研究

采用固体分散技术,利用溶剂法,以处方比例马度米星铵:聚维酮(聚乙烯吡咯烷酮,PVPk30)分别为1:1、1:2、1:3制备了3个马度米星铵固体分散体,通过差示扫描量热法(DSC)分析鉴定,当马度米星铵与PVP k30的比例为1:3时马度米星铵的药物特征吸热峰消失,说明固体分散体制备成功。对药物进行体外累积溶出度研究,结果马度米星铵固体分散体在60 min内体外累积溶出度可达98.46%,比马度米星铵预混剂的2.57%提高了38倍多。抗球虫效果研究表明,马度米星铵固体分散体的抗球虫指数(ACI)为197.7,明显高于ACI为191.8的马度米星铵预混剂。     

发酵床技术在猪生产中的应用

针对发酵床养猪技术的原理及其在养猪生产中的应用效果和存在问题等方面作一综述。     

Agronomic performance of late-season rice under different tillage,straw, and nitrogen management

In double rice-cropping system in China, zero tillage in late-season rice with straw return from early season rice is an emerging technology for saving inputs, shortening the lag time between rice crops, avoiding straw burning, and conserving natural resources. The objective of this 2-year field study was to determine the effects of tillage and straw return on N uptake, grain yield, and N use efficiency of late-season rice. Treatments were arranged in a split-plot design with four combinations of tillage and straw return as main plots and three N management practices as subplots. Tillage was either conventional soil puddling or zero tillage with newly harvested crop residue from early season rice either removed or placed on the soil surface without incorporation. The N treatments were zero-N control, site-specific N management (SSNM), and farmers’ N-fertilizer practice (FFP). Straw return regardless of tillage or N management did not reduce rice yield. In the second year, straw return significantly increased grain yield in the zero-N control. Chlorophyll meter readings at heading and total N uptake at maturity were higher with straw return in the zero-N control, suggesting that straw provides nutrients to rice in the late growing period. Zero tillage did not reduce N uptake, grain yield, and N use efficiency compared with conventional tillage. Despite large differences in timing and rate of N application between FFP and SSNM, these two N treatments resulted in comparable N uptake and grain yield of late-season rice regardless of tillage and straw return. These results suggest that zero tillage after early rice with straw return could replace conventional tillage for late rice in the double rice-cropping system in China.     

2005年上半年禽肉生产与市场综述

2005年上半年国内家禽生产势头好，价格高，效益显著。肉雏鸡价格较往年大幅提高，肉鸡配合饲料价格运行平稳，西装鸡和活鸡价格均高于去年同期水平，人均禽肉消费量同比下降。     

浅谈饲料实验室的管理

质量管理国际化已是当今发展趋势,实验室检验质量管理也应跟上形势,再不能采用行政管理的办法,更不能简单采用一般技术管理方法.实验室管理是对检验工作全过程实行管理,它必须依靠全体工作人员,用管理技术、专业技术、统计方法相结合形成的科学管理方法,来预防质量事故的发生,保证检验结果的可靠性.