夏玉米生理生态与生长特性对干旱过程的响应研究

发布时间：2018-06-28 03:22

本文选题：夏玉米 + 生理生态特性　；参考：《中国气象科学研究院》2015年硕士论文

【摘要】：玉米在世界范围内被广泛种植,其总产量超过小麦和水稻,在三大粮食作物之中居第一。在我国,粮食作物生产快速发展促进全国粮食总产增加,其中玉米贡献率最大。玉米在整个生育期间受旱灾导致的减产,甚至会超过其它因素造成的减产总和。根据2013年在固城生态环境与农业气象试验站开展的夏玉米七叶期开始不同水分变化影响的模拟试验资料,研究了玉米叶片光合特性对干旱发生发展过程的响应及其临界条件,阐明了干旱发生发展对夏玉米生长特性的影响。主要结论有:(1)夏玉米在七叶期灌水处理15天后发生轻旱,一个月后发生中旱,两个月后发生特旱。轻旱条件下,拔节期玉米叶片光合作用存在“午休”现象,顶部第一片展开叶光合速率Pn、蒸腾速率Tr、气孔导度Gs和水分利用效率WUE对干旱响应敏感,具有指示作用。(2)全生育期内玉米叶片Pn、Tr和Gs均随干旱发生发展呈下降趋势,WUE则呈上升趋势。叶片Pn、Tr和Gs前期下降幅度较大,处理间差异显著,随干旱发展,土壤相对湿度差异减小,后期下降幅度减小,处理间差异也减小。WUE前期上升幅度较小,处理间差异也较小,随干旱发展后期上升幅度较大,处理间差异也较大。(3)夏玉米生育期内叶片含水率随干旱发生发展呈线性下降趋势,并与土壤相对湿度显著相关,可表征玉米的受旱程度。随着干旱的发生发展,玉米光合限制因素由气孔限制向非气孔限制转换,干旱强度越大、持续时间越长,叶片光合限制因素转换时间越早,且转换发生时叶片含水率越高。(4)叶片叶绿素含量(SPAD值)对干旱胁迫的响应具有滞后性,不如光合速率等参数灵敏。电子传递速率、光化学猝灭系数和光化学效率由灌浆期至乳熟期表现为十分明显的下降趋势,反映出干旱导致电子传递水平降低,量子效率发生明显下降。(5)夏玉米茎含水率在拔节期达到最大值(93%左右),茎含水率对土壤水分胁迫的响应没有叶片含水率灵敏。土壤相对湿度较高处理的叶面积指数在抽雄阶段达到最大,土壤相对湿度较低处理的叶面积指数在灌浆期达到最大。比叶面积前期呈迅速下降趋势,后期维持稳定并略有下降趋势;比叶重在开花期前呈明显上升趋势,开花期后呈稳定并略有上升趋势,比叶重在生长末期显著高于生长初期。(6)夏玉米地上生物量累积对土壤水分变化反应灵敏,玉米各生育期的生物量干重均随土壤相对湿度的下降而降低。拔节期和抽雄期干旱造成的夏玉米地上生物量增长幅度发生十分明显下降。干旱条件下夏玉米地上生物量平均每天增幅速率在1.15g/d-1.74g/d之间,增幅速率随土壤相对湿度的下降而下降。
[Abstract]:Corn is widely cultivated worldwide, and its total yield exceeds that of wheat and rice, ranking first among the three major food crops. In China, the rapid development of grain crop production promotes the increase of total grain production, among which corn contributes the most. Drought has reduced maize production over the entire growth period, even more than other factors combined. Based on the simulated experiment data of summer maize at seven leaf stage in Gucheng Ecological Environment and Agrometeorological Test Station in 2013, the response of photosynthetic characteristics of maize leaves to drought occurrence and development and its critical conditions were studied. The effects of drought occurrence and development on the growth characteristics of summer maize were expounded. The main conclusions are as follows: (1) mild drought occurred after 15 days, moderate drought occurred after one month, and special drought occurred two months later. Under the condition of light drought, photosynthesis of maize leaves at jointing stage was "midday depression". Photosynthetic rate (PN), transpiration rate (Trr), stomatal conductance (Gs) and water use efficiency (Wue) of the first expanded leaf at the top were sensitive to drought. (2) in the whole growth period, both the Tr and Gs of maize leaves showed a decreasing trend with the occurrence and development of drought, and WUE showed an upward trend. There were significant differences between treatments and treatments. With the development of drought, the difference of soil relative humidity decreased, the latter decreased, and the difference between treatments also decreased. The difference between treatments and treatments was smaller, and the difference between treatments was also small. (3) the leaf moisture content of summer maize decreased linearly with the development of drought, and was significantly related to the soil relative humidity, which could indicate the drought degree of maize. With the development of drought, the photosynthetic limiting factors of maize changed from stomatal limitation to non-stomatal limitation. The greater the drought intensity and the longer the duration, the earlier the conversion time of leaf photosynthetic limiting factors. (4) the response of leaf chlorophyll content (Spad) to drought stress was hysteresis, which was less sensitive than photosynthetic rate and other parameters. The electron transfer rate, photochemical quenching coefficient and photochemical efficiency decreased obviously from milk-filling stage to milk-ripening stage, which indicated that drought resulted in the decrease of electron transport level. (5) the moisture content of summer maize stem reached the maximum at jointing stage (about 93%), and the response of stem water content to soil water stress was less sensitive than that of leaf water content. The leaf area index of the treatment with higher soil relative humidity reached the maximum at the stage of heading and the leaf area index of the treatment with lower soil relative humidity reached the maximum at the filling stage. The specific leaf area decreased rapidly in the early stage, remained stable and slightly decreased at the later stage, and the specific leaf weight increased obviously before anthesis, stabilized and slightly increased after anthesis. The specific leaf weight at the end of growth was significantly higher than that at the early stage of growth. (6) the aboveground biomass accumulation of summer maize was sensitive to the change of soil moisture, and the biomass dry weight of maize decreased with the decrease of soil relative humidity at each growth stage. The increase of aboveground biomass of summer maize caused by drought at jointing stage and heading stage was obviously decreased. The average daily growth rate of aboveground biomass of summer maize was between 1.15g/d-1.74g/d under drought condition, and the increasing rate decreased with the decrease of soil relative humidity.
【学位授予单位】：中国气象科学研究院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S513;S423

【参考文献】