Division of Agricultural Physics, Indian Agricultural Research Institute, Pusa Campus, New Delhi-12, India.
Int J Biometeorol. 2010 Jul;54(4):365-77. doi: 10.1007/s00484-009-0288-2. Epub 2010 Jan 6.
Evaluation of the thermal heat requirement of Brassica spp. across agro-ecological regions is required in order to understand the further effects of climate change. Spatio-temporal changes in hydrothermal regimes are likely to affect the physiological growth pattern of the crop, which in turn will affect economic yields and crop quality. Such information is helpful in developing crop simulation models to describe the differential thermal regimes that prevail at different phenophases of the crop. Thus, the current lack of quantitative information on the thermal heat requirement of Brassica crops under debranched microenvironments prompted the present study, which set out to examine the response of biophysical parameters [leaf area index (LAI), dry biomass production, seed yield and oil content] to modified microenvironments. Following 2 years of field experiments on Typic Ustocrepts soils under semi-arid climatic conditions, it was concluded that the Brassica crop is significantly responsive to microenvironment modification. A highly significant and curvilinear relationship was observed between LAI and dry biomass production with accumulated heat units, with thermal accumulation explaining >or=80% of the variation in LAI and dry biomass production. It was further observed that the economic seed yield and oil content, which are a function of the prevailing weather conditions, were significantly responsive to the heat units accumulated from sowing to 50% physiological maturity. Linear regression analysis showed that growing degree days (GDD) could indicate 60-70% variation in seed yield and oil content, probably because of the significant response to differential thermal microenvironments. The present study illustrates the statistically strong and significant response of biophysical parameters of Brassica spp. to microenvironment modification in semi-arid regions of northern India.
为了了解气候变化的进一步影响，需要评估芸薹属植物在农业生态区的热需求。水热条件的时空变化可能会影响作物的生理生长模式，从而影响经济产量和作物品质。这些信息有助于开发作物模拟模型，以描述不同物候期的作物所存在的不同热环境。因此，目前缺乏关于去分枝微环境下芸薹属作物热需求的定量信息，这促使本研究旨在研究生物物理参数[叶面积指数（LAI）、干生物量生产、种子产量和油含量]对改良微环境的响应。在半干旱气候条件下对Typic Ustocrepts 土壤进行了 2 年的田间试验后，得出结论，芸薹属作物对微环境的改变有显著的响应。LAI 和干生物量生产与累积热量单位之间存在高度显著的曲线关系，热累积解释了 LAI 和干生物量生产变化的>或=80%。进一步观察到，经济种子产量和油含量是当前天气条件的函数，对从播种到 50%生理成熟期间积累的热量单位有显著的响应。线性回归分析表明，生长度日（GDD）可以指示种子产量和油含量的 60-70%变化，可能是因为对不同热微环境的显著响应。本研究说明了在印度北部半干旱地区，芸薹属植物的生物物理参数对微环境改变具有统计学上的强显著响应。
