持续农业、替代农业、中国的生态农业

本文根据我国生态农业的目的意义、基本观点理论和技术工艺方法,对照近来国为外提出的“农业的持续发展”、“持续农业”“立体农业”的实际目的、理论与内容、方法,指出,它们和正在全国推广的中国的生态农业,除了名称不同以外,并没有任何本质上的区别,实际上它们本来就是一个领域的不同说法而已。     

5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)- 1,2-isoxazoline as a useful rice herbicide

5-(2,6-difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1,2-isoxazoline derivative was synthesized, and its herbicidal activity was assessed under glasshouse and flooded paddy conditions. 5-(2,6-Difluorobenzyl)oxymethyl-5-methyl-3-(3-methylthiophen-2-yl)-1,2-isoxazoline demonstrated good rice selectivity and potent herbicidal activity against annual weeds at 125 g of a.i. ha(-1) under greenhouse conditions. Soil application of this compound showed complete control of barnyard-grass to the fourth leaf stage at 250 g of a.i. ha(-1). Field trials indicated that this compound controlled annual weeds rapidly with a good tolerance on transplanted rice seedlings by post-emergence and soil application. This compound showed a low mammalian and environmental toxicity in various toxicological tests.     

Effect of tillage and residue management on enzyme activities in soils

Recent interest in soil tillage and residue management has focused on low-input sustainable agriculture. In this study we investigated the effect of three tillage systems (no-till, chisel plow, and moldboard plow) and four residue placements (bare, normal, mulch, and double mulch) on the activities of four amidohydrolases (amidase, L-asparaginase, L-glutaminase, and urease) in soils from four replicated field-plots. Correlation coefficients (r) for linear regressions between the activities of each of the enzymes and organic C or pH and between all possible paired amidohydrolases were also calculated. The results showed that the effects of tillage and residue management on pH in the 28 surface soil (0–15 cm) samples were not significant. The organic C content, however, was affected significantly by the different tillage and residue-management practices studied, being the greatest in soils with notill/double mulch treatment, and the least with no-till/bare and moldboard/normal treatments. Within the same tillage system, mulch treatment resulted in greater organic C content compared with normal or bare treatment. The activities of the amidohydrolases studied were generally greater in mulch-treated plots than in non-treated plots, and were significantly correlated with organic C contents of soils, with r values ranging from 0.70^*** to 0.90^***. Linear regression analyses of enzyme activities on pH values (in 0.01 M CaCl₂) of the 28 surface soils showed significant correlations for L-asparaginase, L-glutaminase, and urease, with r values of 0.74^***, 0.77^***, and 0.72^***, respectively, but not for amidase (r=0.24). The activities of the four amidohydrolases studied in the 40 soil samples tested were significantly intercorrelated, with r values ranging from 0.72^*** to 0.92^***. The activities of the four amidohydrolases decreased with increasing soil depth of the plow layer, and were accompanied by a decrease in organic C content.     

Long-term cattle manure application in soil

Studies were conducted to investigate the effects of long-term management practices on level and distribution of soil P and enzyme activities involved in P transformations in soil. Treatments included manure, P, NP, NPK, and NPK plus lime. Cattle manure was applied every 4 years at 269 kg N ha^-1 for over a century and chemical fertilizers were applied every year at 67 kg N, 14.6 kg P, and 28 kg K ha^-1 for over 69 years. Total soil P increase in soils ranged from 4.5 to 10.3 kg P ha^-1 year^-1 with the highest increase detected in the P-treated and the lowest in the manure-treated plot. Approximately 77-86% of the applied inorganic fertilizer-P in the past 69-71 years was recovered either in the harvested grain or remained in the top 30 cm of soil, while only 32% of the applied manure-P was recovered. Microbial biomass C and activities of alkaline phosphomonoesterase, phosphodiesterase, inorganic pyrophosphatase, and dehydrogenase were significantly higher in the soil treated with cattle manure. Acid phosphomonoesterase activity, however, was significantly higher in soils treated with chemical fertilizers. Results from this study suggested that manure-P is relatively more mobile than inorganic fertilizer-P. Long-term application of cattle manure promoted microbiological activities and P cycling, but did not result in P accumulation to levels close to those in inorganic P fertilizer-treated soils.     

农牧交错带牧业系统波动性及影响因子分析

牧业系统波动是影响到农牧交错带农户生计和生态安全的重大问题。该研究以羊只总数为牧业系统特征变量,选取年降水量、年平均气温、有效灌溉面积、粮食播种面积、粮食总产量、当年造林面积、草地面积、植被指数、农业劳动力人数和农民人均纯收入为影响因子。用经验模态分解法获得羊只总数及其10个影响因子的波动分量和趋势量;进而运用集对分析法对羊只总数与其影响因子的相应波动分量进行对比分析。结果表明,1954—2013年盐池县羊只总数波动较大,羊只总数及其10个影响因子存在3~4、7~15、22~26、40~45 a的准周期性波动,22~26 a准周期是羊只总数波动中最重要的。对羊只总数波动影响最大的因子是粮食播种面积,其次是年降水量,二者的综合影响率占75%。年平均气温、粮食总产量和造林面积也有一定影响。羊只总数波动分量的周期越长,受农业的影响越大;越短则受气候的影响越大。经济社会对羊只总数的波动影响很小。气候因子在3、7~9和30 a准周期上影响羊只总数波动,是其主控因子;而粮食总产量、当年造林面积是羊只总数波动的反向调节因子,其他6个因子兼有主控和反向调节两方面的作用。基于以上各主要影响因子的作用机理,构建有效的农林牧复合系统将是实现盐池县牧业系统稳定发展的必然出路。     

Genetic analysis and associated SRAP markers for flowering traits of chrysanthemum (<Emphasis Type="Italic">Chrysanthemum morifolium</Emphasis>)

The inheritance of two flowering traits of chrysanthemum, initial blooming time and the duration of flowering, was investigated using segregation within an F ₁ population derived from a cross between the autumn-flowering ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ cultivars. The analysis, based on a single segregating generation and the major gene plus polygene mixed inheritance model, showed that the inheritance of both traits was compatible with the presence of two pairs of major genes displaying additivity–dominance–epistasis, with additivity predominating. As the heritability of both pairs of major genes was high (initial blooming time ~65%, duration of flowering ~72%), it should be possible to select for both traits in early breeding generations. A marker-trait association analysis based on sequence-related amplified polymorphism (SRAP) genotyping uncovered 10 (initial blooming time) and 12 (duration of flowering) markers significantly associated with phenotype, cumulatively explaining, respectively, 46 and 54% of the variation. Some potentially useful markers were identified.     

种植密度对夏玉米穗位叶片解剖结构的影响

为了研究种植密度对玉米穗位叶片解剖结构的影响, 以生产上广泛种植的玉米杂交种郑单958和浚单20为材料,采用石蜡制片和超薄切片法对不同种植密度下2个玉米品种穗位叶片和叶绿体的结构进行了观察分析。结果表明, 随着种植密度的增加,2个玉米品种的叶片厚度、叶脉横截面积和叶脉木质部面积减小,上、下表皮的气孔频度减少(郑单958显著,浚单20不显著),叶肉细胞叶绿体的基粒数量减少,维管束鞘细胞叶绿体的数量减少;种植密度在75 000株 hm^-2时产量最高。相关性分析显示,叶脉木质部面积、气孔频度、叶肉细胞叶绿体的基粒数量、叶肉细胞叶绿体的基粒数量与种植密度呈显著负相关,与单穗籽干重、千粒重、穗粒数量呈显著正相关,因而成为玉米生产上的重要结构指标。     

玉米胚性愈伤组织继代及侵染条件的优化

设计了含有不同2,4-D浓度的6种培养基用于玉米胚性愈伤组织的继代培养,对影响转化效率的侵染条件进行了研究,根据转化后所得的抗性愈伤组织数目及其分化率的评估结果表明,选用N6为基本培养基,添加1mg/L 2,4-D时,胚性愈伤组织继代长势较好,且在真空渗透的情况下,侵染5min,抗性愈伤组织数最多。经初步的PCR鉴定,利用优化的玉米遗传转化体系得到了转基因玉米植株。     

几种新型食品保鲜技术的研究进展

针对传统食品保鲜技术存在的缺陷,对冰温贮藏、辐照贮藏、高压脉冲电场、超高压杀菌技术和纳米保鲜等新型的食品保鲜技术的特点及其研究进行总结,以期为新型食品保鲜技术研究发展提供参考。     

Surface discharge characteristics and gas generation law inoil-paper insulation of transformer

Based on a surface discharge model, partial discharge experiment in the simulation transformer tank is carried out to research the development characteristics and characteristic parameters’ variation law of surface discharge in transformer oil-paper insulation, and the variation characteristic of dissolved gases in oil in the discharge process is emphatically researched. The results show that the surface discharge value increases at the beginning stage of the discharge process, and reaches its maximum after 2~3 h, then it decreases gradually. As the development of partial discharge, the absolute generation speed of CO fluctuates around a certain value with small variation. While, the absolute generation speeds of H2 and CH4 increase first and then decrease, and the variation of discharge spectrum is highly similar to the variation of oil-dissolved gas’ absolute generation speed.