3株烟草内生细菌促进作物生长作用的研究

通过漂浮育苗试验以及大田试验,研究了烟草内生细菌YN201408、YN201442和YN201448的促生长作用。结果表明:3个菌株的菌悬液均可促进烟草、番茄、白菜、玉米和油菜的生长,其中YN201448对烟草和番茄的促生长效果最好,YN201408促进白菜生长的作用较大,而YN201442对玉米和油菜的促生长作用最好。     

优化碳同化实现作物高光效研究进展

随着全球人口的持续增长和耕地面积的不断减少,人类生存所面临的粮食危机越来越严重。进一步提高作物产量是保障我国粮食生产安全的重要途径。光合作用是作物产量形成的物质基础,采用现代育种技术以提高作物光合效率为中心的作物改良被认为是新一轮的“绿色革命”。本文从提高Rubisco羧化活性、将C₄光合途径引入C₃作物、降低光呼吸碳耗损等方面,介绍了优化改进植物光合碳同化领域的研究进展、存在的瓶颈问题,以及提高作物光合效率的实践应用;对当前改善植物光合碳同化的研究重点和方向进行了展望。     

硒营养在作物科学中的研究进展

硒是一种人体必需的微量元素,对植物生长发育的影响呈现出Bertrand生物剂量规律。硒通过参与植物体内的蛋白质代谢、能量代谢、抗氧化作用以及与其它元素的相互作用而发挥其生理功能。介绍了硒营养在作物科学上的研究状况,概述了施硒对粮食作物(水稻、小麦)、经济作物(烟草、茶叶、油菜、大豆)以及其他作物的影响,并提出了进一步加强硒素营养研究的建议。     

Spectral vegetation indices for benchmarking water productivity of irrigated cotton and sugarbeet crops

Irrigation performance and water productivity can be benchmarked if estimates of spatially distributed yield and crop water use are available. A commonly used method to estimate crop evapotranspiration in irrigated areas is to multiply reference evapotranspiration values by appropriate crop coefficients. This study evaluated convenient ways to derive such coefficients using multispectral vegetation indices obtained by remote sensing. Detailed ground radiometric measurements were taken in small plots perpendicular to the crop rows to obtain canopy reflectance values. Ancillary measurements of green ground cover, plant height, leaf area index and biomass were taken in the cropped strip covered by the radiometer field-of-view. The results were up-scaled using 10 Landsat-5 and 1 Landsat-7 images. Crop measurements and ground radiometry were made at the time of Landsat overpass on two commercial fields, one grown with sugarbeet and the other with cotton. Crop height and ground cover were determined weekly in these two fields, three additional sugarbeet fields and one additional cotton field. The ground and satellite observations of canopy reflectance yielded similar results. Two vegetation indices, the normalized difference vegetation index (NDVI) and the soil adjusted vegetation index (SAVI) were evaluated. Both indices described the crop growth well, but SAVI was used in further evaluations because it could be conveniently related to both ground cover and the basal crop coefficient using a simple model. Based on these findings, crop water use variability was analyzed in a large sample of sugarbeet and cotton fields, within a homogeneous irrigation scheme in Southern Spain. The yield versus evapotranspiration data points were highly scattered for both cotton and sugarbeet. The yield values obtained from the sugarbeet fields and cotton fields were substantially lower than values predicted by a linear yield function, and close to a curvilinear yield function, respectively. Evapotranspired water productivity varied in the cotton fields from 0.3 to 0.78 kg m⁻³, and in the sugarbeet fields from 7.15 to 14.8 kg m⁻³.     

Cropping systems and crop residue management in the Trans-Gangetic Plains: Issues and challenges for conservation agriculture from village surveys

Conservation agriculture practices are being advocated to help sustain crop productivity gains and secure environmental sustainability in the Trans-Gangetic Plains, India’s Green Revolution heartland. The paper illustrates the use of village surveys as a quasi-quantitative system analysis tool to derive implications for agricultural research and development. Drawing from village surveys in 170 communities, the paper assesses current crop residue management practices in Punjab and Haryana’s rice-wheat, basmati-wheat and non-rice-wheat cropping systems. The prevalence of wheat as the winter crop implies an intensive collection, trading and use of wheat straw as basal feed for dairy livestock; which contrasts with the diverse crop residue management of the monsoon crops. The increased use of combine harvesters has spurred the rapid advent of mechanical wheat straw reapers whereas the bulk of combine harvested rice straw is burned in situ. Present crop residue management practices are largely incompatible with year-round mulch retention despite significant biomass production. The research and development community faces the challenge of evening out straw use and management over seasons to ensure at least partial residue retention if its calls for conservation agriculture in this important sub-region are to succeed. The paper also reiterates the worrying decline of groundwater tables associated with the rice-wheat system.     

Cover crop effects on nitrogen load in tile drainage from Walnut Creek Iowa using root zone water quality (RZWQ) model

Studies quantifying winter annual cover crop effects on water quality are mostly limited to short-term studies at the plot scale. Long-term studies scaling-up water quality effects of cover crops to the watershed scale provide more integrated spatial responses from the landscape. The objective of this research was to quantify N loads from artificial subsurface drainage (tile drains) in a subbasin of the Walnut Creek, Iowa (Story county) watershed using the hybrid RZWQ-DSSAT model for a maize (Zea mays L.)-soybean [Glycine max (L.) Merr.] and maize-maize-soybean rotations in all phases with and without a winter wheat (Triticum aestivum L.) cover crop during a 25-year period from 1981 to 2005. Simulated cover crop dry matter (DM) and N uptake averaged 1854 and 36 kg ha⁻¹ in the spring in the maize-soybean phase of the 2-year rotation and 1895 and 36 kg ha⁻¹ in the soybean-maize phase during 1981-2005. In the 3-year rotation, cover crop DM and N uptake averaged 2047 and 44 kg ha⁻¹ in the maize-maize-soybean phase, 2039 and 43 kg ha⁻¹ in the soybean-maize-maize phase, and 1963 and 43 kg ha⁻¹ in the maize-soybean-maize phase during the same period. Annual N loads to tile drains averaged 29 kg ha⁻¹ in the maize-soybean phase and 25 kg ha⁻¹ in the soybean-maize phase compared to 21 and 20 kg ha⁻¹ in the same phases with a cover crop. In the 3-year rotation, annual N loads averaged 46, 43, and 45 kg ha⁻¹ in each phase of the rotation without a cover crop and 37, 35, and 35 kg ha⁻¹ with a cover crop. These results indicate using a winter annual cover crop can reduce annual N loads to tile drains 20-28% in the 2-year rotation and 19-22% in the 3-year rotation at the watershed subbasin scale over a 25-year period.     

Evapotranspiration and crop coefficient of Populus euphratica Oliv forest during the growing season in the extreme arid region northwest China

Based on successive observation, fifteen-day evapotranspiration (ET_c) of Populus euphratica Oliv forest, in the extreme arid region northwest China, was estimated by application of Bowen ratio-energy balance method (BREB) during the growing season in 2005. During the growing season in 2005, total ET_c was 446.96 mm. From the beginning of growing season, the ET_c increased gradually, and reached its maximum value of 6.724 mm d⁻¹ in the last fifteen days of June. Hereafter the ET_c dropped rapidly, and reached its minimum value of 1.215 mm d⁻¹ at the end of growing season. The variation pattern of crop coefficient (K_c) was similar to that of ET_c. From the beginning of growing season, the K_c value increased rapidly, and reached its maximum value of 0.623 in the last fifteen days of June. Afterward, with slowing growth of P. euphratica, the value dropped rapidly to the end of growing season. According to this study, the ET_c of P. euphratica forest is affected not only by meteorological factors, but by water content in soil.     

CO_2浓度增加对C_3、C_4作物生理特性影响的实验研究

通过对 C3小麦、大豆、大白菜和 C4 玉米在不同 CO2 浓度 ( 350× 10 -5、 50 0× 10 -6、 60 0×10 -6、 70 0× 10 -6)条件下的生长模拟实验和生理特性研究表明 ,CO2 浓度增加 ,促使作物光合速率增长 ,光合时间略有延长 ,光补偿点明显下降 ,蒸腾系数减小 ,叶气温差增大 ,叶温升高。 70 0× 10 -6和50 0× 10 -6比 350× 10 -6小麦光合速率分别增长 30 .7%和 11.7% ,大豆增长 63.4 %和 4 2 .7% ,大白菜增长 68.0 %和 39.0 % ,玉米增长 15.7%和 4 .7% ,C3作物比 C4 反应明显 ;蒸腾系数小麦下降 14.3%和 7.7% ,大白菜下降 2 7.1%和 2 3.1% ,玉米下降 16.8%和 10 .4 %     

水旱轮作大豆的营养生长与根系活力的关系

大豆是实行水旱轮作制度的重要作物之一,水田的排水不良是导致轮作大豆减产的重要原因.通过对水旱轮作大豆幼苗进行过湿处理,分析了不同大豆品种的营养生长特性与根系生理活性的关系.轮作大豆在过湿条件下,所有品种的生育都受到抑制,干物质生产受抑制程度存在着品种间的差异.营养生长诸性状中,伤流速度受过湿处理影响最大,处理区的伤流速度仅为对照区的64.2%.过湿处理导致伤流液中氮含量几乎减少了一半,伤流中的氮含量与叶片氮素含量之间存在极显著正相关关系,过湿条件下叶片氮含量的减少是由于根的氮素吸收能力的低下所致.遭遇过湿逆境时的植株个体大小与维持物质生产关系密切.过湿处理期间及其后的干物质增加量的大小与以伤流速度为代表的根系活力密切相关,说明从田间管理技术上提高大豆的根系活力以维持水旱轮作大豆的干物质生产是可行的.     

作物孤雌生殖及其应用研究进展

系统介绍了孤雌生殖的概念及分类,总结了孤雌生殖在作物育种中的应用和重要意义,阐述了孤雌生殖后代的相关鉴定方法,并将孤雌生殖技术与传统育种方法作了对比,提出了孤雌生殖发生机理、诱导概率问题是今后的研究重点。