砾石覆盖量对夏玉米作物系数及水分利用效率的影响

摘要

In order to evaluate the effects of gravel mulching in arid and semi-humid regions of China on soil water storage ,crop growth ,crop yield and water use efficiency ,based on the measured data of summer corn grown at Yangling in 2014 and the meteorological data ,evapotranspiration of the reference crop was calculated at various growth stages by adopting the formula of Penman-Monteith .The actual crop evapotranspiration was calculated by adopting the formula of field water balance equation ,then the variation of the crop coefficient of different growing periods was analyzed ,as well as the water use efficiency under different mulching levels .The results showed that gravel mulching could maintain water at the beginning of crop growth by 12 .8% ,reaching the maximum at the jointing stage ,and then became decreased be-cause of canopy .A linear relationship between gravel degree and crop coefficient was found .The larger the amount of coverage ,the higher the increases of the corresponding crop coefficients at different growing stages .Leaf area and plant height had good regression relationships with crop coefficient ,and thus corn evapotranspiration can be forecasted during the growth period .Gravel mulching made the growing period shortened ,reaching a the maximum of nineteen days .Grav-el mulching also preserved soil moisture better ,and reduced soil evaporation ,increased soil water storage and water re-tention capacity ,thereby increasing crop water use efficiency and yield by 4 .65% ~38 .17% and 2 .94% ~32 .00% ,respectively .The effects became enhanced when the mulching coverage was increased extensively within the extent of this research .%为评价半湿润易旱地区砾石覆盖对土壤贮水量、作物生长与产量及水分利用效率的影响，利用杨凌地区夏玉米2014年实测数据及气象数据，基于Penman－Monteith公式计算了砾石不同覆盖量下全生育期内参考作物蒸发蒸腾量，并根据FAO推荐的分段单值平均法，计算夏玉米各生育期作物系数，以及砾石不同覆盖量下作物水分利用效率。结果表明：砾石覆盖的保水效果主要体现在作物生长初期，拔节期最大砾石覆盖处理0～200 cm土壤贮水量较对照增大12．8％，后期由于冠层覆盖影响其效果减弱；夏玉米全生育期作物系数与覆盖量呈线性关系；覆盖量越大，不同生育阶段的作物系数也相应增加；叶面积和株高与作物系数有着较好的回归关系，可以对生育期内的玉米蒸散量进行预报；砾石覆盖可以缩短夏玉米生育期的天数，最大可缩短19 d；砾石覆盖能促进作物生长，提高作物产量，且在该试验覆盖量范围内，覆盖量越大，增产增效越明显，随覆盖量增加，各处理分别较对照提高4．65％～38．17％；作物水分利用效率随覆盖量的增大分别较对照提高2．94％～32．99％。