Effects of different soil management practices on total P and Olsen-P sediment loss: A field rainfall simulation study

Field rainfall simulations were conducted in 2002 and 2005 to study the effects of different soil management practices on the total phosphorous (TP) and Olsen-P losses by soil erosion and redistribution along a 15 m long slope in Luoyang, Henan province, China. Field plots were set up in 2001 and included the following soil management practices: subsoiling with mulch (SSM), no-till with mulch (NTM), reduced tillage (RT), and a conventional tillage control (CT). The results showed that there were no significant differences in TP and Olsen-P content in the sediment load between different plots after 6 years uniform tillage practices. The enrichment of TP and Olsen-P at the lower slope showed a clear redistribution along the slope. Effects of tillage practices on the temporal pattern of the enrichment ratio (ER) of TP and Olsen-P was not uniform. ER_TP values were initially high and diminished after a short period of time and leveled to the end of the rainfall test in CT and RT plots, but remained ≥ 1. The ER of Olsen-P at the end of rainfall simulation showed a significant difference when compared to the initial stage, 0.78 to 1.60, respectively. However, the temporal loss rate of TP and Olsen-P showed a similar pattern because it was more depending on the sediment loss rate than on the concentration in the sediment. SSM resulted in 96% less TP and Olsen-P erosion loss compared to CT in 2002. Also, SSM showed the highest reduction in TP and Olsen-P loss after 4 years consistent practice. RT reduced TP and Olsen-P loss by 30%, although the runoff reduction was not significant. NTM was the best alternative with respect to TP and Olsen-P conservation, when considering its lower operational costs.     

不同养蜂合作组织形式对蜂蜜质量控制效果探讨

本文对2006年至2008年不同养蜂合作组织形式提供的蜂蜜原料进行了质量跟踪,对蜂蜜原料中的果糖和葡萄糖、蔗糖、羟甲基糠醛、淀粉酶活性、氯霉素、四环素族抗生素、碳-4植物糖含量等指标进行了检测分析,研究结果表明：不同的养蜂合作组织形式,由于对组织内养蜂户管理力度不同,其所生产的蜂蜜质量也有所不同。以亲情纽合的联合方式、产地公司＋当地固定养蜂户的联合方式和供应商＋转地固定养蜂户的联合方式生产的原料蜂蜜质量可靠性较强;公司＋无固定养蜂户的联合方式效果较差。     

江苏省花卉行业的现状、存在的问题与对策

通过对江苏省花卉行业产品结构、地区结构、生产组织形式、从业人员情况等现状的分析,认为江苏花卉行业存在开发创新能力不强、花卉整体质量偏低、成果转化率低、花卉统计制度不完善等问题,并针对这些问题提出了对策和建议.     

反硝化聚磷菌C18脱氮除磷特性研究

从城市生活污水处理厂好氧池活性污泥中筛选出的一株反硝化聚磷菌C18,经16S rDNA初步鉴定为假单胞菌(Pseudomonas grimontii)。C18在pH 6.5~7.5之间能正常生长,pH为7.5时,脱氮除磷效果最好。C18生长对温度没有特殊要求,当温度为30℃时,磷和氨氮去除率分别达到85.9%和83.6%。厌氧/缺氧最佳连续培养时间为厌氧2 h、缺氧4 h。     

应用“林分结构复原法”评价经营措施及更新效果研究

介绍了林分调查的一种方法：“林分结构复原法”,即根据林分的现时直径分布和直径生长量,应用林分表法进行径阶转移的原理,推算n年前的直径分布,并根据直径与其他林分因子的关系,再现林分在前n年时的林分结构,从而为评价采伐的合理性以及鉴定超采、盗伐提供可靠数据。     

仲裁协议研究

仲裁协议是合同中订立的仲裁条款和以其他书面方式在纠纷发生前或者纠纷发生后达成的请求仲裁的协议。目前,我国《仲裁法》对仲裁协议的形式要求仅仅是书面形式。随着科学技术尤其是电子通讯技术的发展,可实现合意目的的手段呈现出多样化趋势,不再仅限于传统的书面形式和签字。为适应仲裁发展的需要,在我国司法实践中,也出现了放宽对仲裁协议书面形式限制的倾向。在此,文章就对仲裁协议形式的扩大解释提出一些建议。     

镉胁迫下不同品种烟草镉化学形态分布研究

为研究镉胁迫下不同品种烟草积累和忍耐镉的差异及机制问题,以烟草品种‘RG17’、‘贵烟11号’、‘Xanthi’为试验材料,采用土培试验方法对不同品种烟草镉化学形态分布特征进行了研究。结果表明,烟草根、茎、叶镉的各形态含量随土壤镉浓度的增加而增加,根部FHAC分配比率最高,占绝对优势,茎FHAC降低,FNaCl增加,而叶片FNaCl分配比率最高,占绝对优势,且随着镉浓度的加大,根、茎、叶镉的各形态分配比率有接近的趋势。同样各形态分配比率因品种而异,根部‘Xanthi’FHAC分配比率最高,而FW、FNaCl分配比率低;叶内FNaCl分配比率‘Xanthi’高于其他品种,而FW分配比率低,随着镉浓度的增加,这种趋势更加明显。推断高积累型烟草根内镉形成难溶于水的磷酸盐有利于其对镉的积累,而与蛋白质络合,从细胞质转移到液泡可能是烟草耐性品种忍耐镉的主要机制之一。     

雪松在园林绿化中的应用

介绍了雪松的生物学特性和生态习性,分析了其作为园林绿化树种在观赏性、防护作用、经济价值及文化价值中的作用,阐述了其孤植、对植、列植、从植、群植5种造景形式,并论述了其在城市街道、居民区、厂区和工业区、风景区和森林公园5类不同区域园林绿化中的应用。     

不同氮素形态对延边烤烟几种关键酶活性的影响

以吉烟9号为材料,通过大田试验,研究吉林省东部地区烤烟不同氮素形态配比对保护酶（SOD、CAT、MDA）硝酸还原酶（NR）、转化酶的影响.结果表明：在抗氧化酶上,不同部位烟叶SOD及CAT活性的变化趋势为上部叶〉中部叶〉下部叶;在丙二醛含量上,从小到大依次为上部叶、中部叶和下部叶;处理间进行比较,处理C（50%∶50%）在抗氧化酶方面比其它处理都高,且丙二醛含量比其它处理都低;说明处理C的抗逆性最强,处理D、B次之;在INV、NR及INV/NR方面,不同叶位INV、NR的酶活性变化趋势均为上部叶〉中部叶〉下部叶,且随着铵态氮用量下降和硝态氮用量上升呈先上升后下降的单峰曲线,当配比50%：50%时达到最高值,表明适当的氨硝比能够增强植株抗逆性,并促进植物的碳氮代谢.     

Nitrogen nutrition and adaptation of glycophytes to saline environment: a review

Relations between nitrogen (N) nutrition and salinity tolerance in plants are multifaceted and varies significantly depending on many soil and plant factors. Saline environment might experience an N dilemma due to the opposing effects of salt ions on N uptake, translocation and metabolism within the plant body. Adequate regulation of N under saline conditions can be a promising approach to alleviate salinity’s effects on plants by ameliorating ion toxicity and nutrient imbalances through its impacts on the uptake and redistribution of salt ions within the plant. Certain N-containing compounds including proline, glycine betaine, proteins and polyamines help the plants to tolerate salinity through their involvement in improving water uptake and water use efficiency, membrane integrity, enzyme activation, hormonal balance, chlorophyll synthesis, stimulation of photosystems and CO₂ assimilation under salinity stress. Nitrogen, particularly NO₃^? represents a stress signal that triggers the activation of antioxidant enzymes to protect the plants against salinity-induced oxidative damage. Furthermore, the source/form of N application can affect not only N-interactions but also the behavior of other nutrients in stress environment. The present review deals with N-salinity relations in plants, particularly glycophytes, emphasizing on N-induced mechanisms which can improve plant adaptation to saline environment.