我国牧草种植成本收益变化与比较     

石自忠  王明利  胡向东  崔姹 《草业科学》2017,34(4)

本研究以牧草种植户牧草及粮食作物的调研数据为基础,计算出2010-2014年主要牧草和粮食作物的成本收益基本信息,对其变化进行统计分析,并对各作物的成本收益进行比较。分析发现,2014年苜蓿(Medicago sativa)的经济效益有所下降;黑麦草(Lolium perenne)和青贮玉米(Zea mays)的纯收益和收益率有所增长;苜蓿的纯收益和收益率要高于黑麦草和青贮玉米;马铃薯(Solanum tuberosum)和苜蓿的经济效益更具优势,种植小麦(Triticum aestivum)经济效益较差;黑麦草和青贮玉米人工和土地成本更高,苜蓿水电费最高。建议调整农业产业结构,推行"粮+经+饲+草"四元种植结构,全面扶持牧草产业发展,建立健全牧草生产资料补贴制度。  相似文献   

筒式结构拆除的力学分析     

言志信 《中南林业科技大学学报(自然科学版)》1996,(4)

根据力学原理，分析讨论了钢筋混凝土筒式结构定向倾倒的切口高度和切口角度．  相似文献   

硝酸还原酶与氮素利用的关系及其在作物遗传育种中的应用(综述)     

孙宝启  李玉京 《中国农业大学学报》1993,(3):29-34

本文综述了硝酸还原酶与氮素利用的关系及其遗传特性和在作物育种中应用的某些最新进展。氮吸收、利用等性状的生理和遗传特性极其复杂,受环境影响很大,对其进行遗传改良需考虑多种指标。对硝酸还原酶活性(NRA)与品质性状和产量的关系的争论很多,有些研究表明 NRA 可作为品质、产量性状的选择指标,有些则相反。逆境条件下 NRA 的变化非常敏感,NRA 可能与抗逆性有关。  相似文献   

小麦矮秆育种中性状间关系的多元分析   总被引：12，自引：0，他引：12  

何中虎  张树榛 《华北农学报》1992,7(1):1-7

以7个株高梯度系列的35个系统及5个亲本品种为材料,采用典范分析和逐步回归分析研究了株高及其构成因子与产量因子、产量生理性状间的关系。结果表明:①株高因子通过产量生理性状影响产量因子,一定的生物学产量是获得高产的基础。②矮秆品种的高化对提高产量、千粒重和收获指数有利,对蛋白质含量的影响不明显;高秆品种矮化能显著提高收获指数,对籽粒的蛋白质含量影响不大。③在主要性状符合育种目标的前提下,选择倒二节间较长、第一和第二叶间距略长、穗颈和穗部较长的类型可能对提高产量有利。  相似文献   

Demography of Abutilon theoprasti and Setaria faberi in three crop rotation systems     

A H HEGGENSTALLER  & M LIEBMAN 《Weed Research》2006,46(2):138-151

Field experiments were conducted to characterize the demography of Abutilon theophrasti and Setaria faberi in a conventionally managed 2‐year (maize/soya bean) rotation, and in 3‐year (maize/soya bean/triticale + red clover) and 4‐year (maize/soya bean/triticale + lucerne/lucerne) rotations managed with 72% and 79% lower herbicide inputs respectively. Rates of weed seedling recruitment, seedling survival and adult plant fecundity were determined for populations in each phase of each rotation and used to calculate annual rates of weed population change, Δ. In both years of the study, Δ for A. theophrasti populations declined or remained stable in all three rotation systems. Despite greater rates of seedling survival and fecundity in maize and soya bean in the 3‐ and 4‐year rotations, increases in Δ for A. theophrasti populations were prevented in these systems because of low fecundity in triticale and low seedling survival and fecundity in lucerne. For Setaria faberi populations, Δ remained stable in the 2‐year rotation, increased in the 3‐year rotation in both years, and increased in the 4‐year rotation in 1 year. The results of this study indicate that when herbicide use is reduced, rotations that include triticale and lucerne can facilitate the suppression of A. theophrasti. Rotations that include lucerne can contribute to restraining S. faberi population growth, given adequate levels of seedling mortality in this crop.  相似文献   

四川的云南松地径胸径相关关系及其应用研究   总被引：9，自引：1，他引：8  

卢昌泰 《四川林业科技》2004,25(2):46-49

本文报道了四川的云南松树干在部三个不同部位直径(地表直径d0．00、0.05m高处直径d0.05、0.1Om高处直径d0.10)与胸径(d1．3)的相关关系，利用其编制了四川云南松地径一元材积表，并对其在四川云南松林区进行盗伐木、滥砍乱伐木材积估计和监测森林资源消耗量等方面的应用进行了探讨。四川云南松地径与胸径最佳关系模型为二次抛物线回归方程，相关系数r=0，999217～0．999380，剩余平方和Q=179．3391～226．4480，且d0.10与d1．3相关关系最为紧密。  相似文献   

水稻旱作对其生长量和经济产量的影响   总被引：11，自引：0，他引：11  

黄文江  黄义德  王纪华  李金才 《干旱地区农业研究》2003,21(4):15-19

1998～1999年，研究了水稻旱作条件下，不同生育时期受水分胁迫后对作物生长量的影响。结果表明：不同指标对水分胁迫时期的敏感性不一，植株高度对抽穗期水分胁迫最敏感；单株绿叶面积和单株地上部干重对幼穗分化后期水分胁迫最敏感；根系干重和根冠比对幼穗分化前期水分胁迫最敏感；幼穗分化后期水分胁迫对经济产量影响程度最大，无效分蘖期水分胁迫对产量影响程度最小。  相似文献   

作物害虫的猖獗与高毒农药的"倾泻"的治理对策   总被引：3，自引：0，他引：3  

韩新才  黄志农  边银丙 《农药科学与管理》2003,24(4):27-29

阐述了我国农作物害虫发生现状及化学农药防治的现状，分析了作物害虫猖獗与高毒农药“倾泻”的原因与发展，提出了防止作物害虫猖獗和高毒农药“倾泻”的5条对策，即做好高毒农药危害性的宣传工作，提高农民禁用、限用高毒农药的自觉性；调整农药产品结构，大力发展生物农药；生物农药与化学农药复配，促使高毒农药低毒化；推广转基因作物；推广使用高效、高选择性、低毒、低用量、安全农药。  相似文献   

Weed:spring barley competition for applied nitrogen in pig slurry   总被引：2，自引：0，他引：2  

J Petersen 《Weed Research》2003,43(1):33-39

Summary The experiments were carried out in the two spring barley fields of the organic six-course cattle:crop rotation at Foulumgaard, Denmark. The weed density was 300 and 1800 plants m⁻² respectively. Pig slurry was applied by hand in microplots by four methods: broadcasting followed by incorporation, or injected in bands to depths of 5, 10 or 15 cm. Spring barley and weeds were sampled separately six times during the tillering and elongation phase of the spring barley. The effect of application method on dry-matter (d.m.) production, nitrogen uptake and recovery of applied nitrogen in the spring barley and the weeds is reported. Slurry banding halved the weed d.m. and weed N uptake compared with broadcasting, irrespective of weed density. Weeds recovered up to 12% of the applied nitrogen, which made them a significant competitor when the slurry was broadcast and incorporated. Banding by direct injection reduced the slurry:soil contact and the weed:crop competition balance for applied nitrogen moved in favour of the crop. Thus, the crop recovery of applied nitrogen at the end of the sampling period was increased from approximately 45% for broadcast and incorporated to approximately 50% for injected slurry, and coincidental weed recovery was reduced to a maximum of 5%. As the nitrogen supply normally affects plant d.m. production, banding of slurry might well improve crop competitiveness and its tolerance to mechanical weed control.  相似文献   

果树转基因研究进展与产业化展望   总被引：11，自引：1，他引：11  

杨莉  徐昌杰  陈昆松 《果树学报》2003,20(5):331-337

综合有关文献归纳了15年来果树转基因研究成果,其中包括:(1)已实现转基因的果树种类,目前世界和我国的大宗水果苹果、柑橘、梨、桃、葡萄、香蕉、猕猴桃和草莓等均已成功实现遗传转化;(2)通过转基因改变的农艺学性状类型,如抗病虫、抗逆、提高果实贮藏性能、缩短童期和改善果实品质等;(3)对几个重要的遗传转化研究实例作了具体介绍。同时还阐述了转基因果树产业化现状和大田试验现状,探讨了转基因果树产业化进程滞后的原因和发展前景以及促进果树产业化发展可采取的一些策略。  相似文献