火烧和刈割对关中地区紫花苜蓿生长特性及土壤水分变化的影响

Effects of firing and cutting treatment on alfalfa growth characteristics and soil water changes in Guanzhong area

为了探究紫花苜蓿生育期内植株动态生长规律及对土壤0-300 cm深度水分变化的影响,试验以2年生的紫花苜蓿为研究对象,在返青前对前茬分别进行火烧和刈割处理,记录整个生育期内植株株高的动态变化,并在开花期植株生长基本停滞阶段采集0-300 cm深度土层土壤测定含水量。结果表明：火烧和刈割处理后的紫花苜蓿生长轨迹一致;火烧处理后的紫花苜蓿相比刈割处理返青期提前、最大生长速率出现时间提早,在返青期到现蕾期火烧处理后的紫花苜蓿株高显著高于刈割处理,但在结荚成熟期两者株高无显著差异;火烧处理后的紫花苜蓿土壤含水量分布曲线呈＂〈＂字型,刈割处理后呈＂3＂字型;火烧处理后的紫花苜蓿相比刈割处理土壤含水量更低,相对土壤干层厚度更厚,在0-200 cm土层深度两者土壤含水量差异显著,在200-300 cm土层深度两者无显著差异;紫花苜蓿生长对土壤水分是消耗过程,株高动态变化与土壤垂直层面含水量变化呈显著负相关,尤以火烧处理后0-200 cm土层负相关性更强。说明根据植株生长轨迹和土壤水分分布规律,在保证土壤水分充足的情况下火烧处理相比刈割处理有利于紫花苜蓿提早、提快生长。

The aim of the present study was to explore the dynamic growing law of alfalfa and analyze the influence on water content of soil（depth： 0-300 cm）. The 2-year alfalfa was selected as research object. Before its turning green,the front stubble alfalfa was treated by firing and cutting,respectively. The dynamic changes of the plant height in their whole growth period were recorded,and the soil layers（depth： 0-300 cm） were collected to measured its water content in alfalfa＇s flowering period while the growth of plants was almost at a standstill. The results showed that the growth process curve of alfalfa after firing and cutting treatment revealed a similar trend. The reviving period of alfalfa after firing treatment was earlier than that after cutting. Meanwhile,the maximum growth rate appeared slightly earlier than that after cutting. From reviving period to budding period,the plant height of alfalfa after firing treatment was obviously higher than that after cutting treatment. However,from flowering period to poding period,there was no significant difference in both plant height. After firing,the soil water content distribution curve showed a＂＂change,but after cutting it presented a＂3＂change. Compared with cutting treatment,the soil water content was changed to be lower,and the soil dry layer become thicker after firing treatment. The water content of soil after firing treatment was obviously lower than that after cutting treatment in 0-200 cm depth,while the soil water content showed no significant difference in 200-300 cm depth. The growth of alfalfa was a process of soil water consumption,and the dynamic change of plant height and soil water content change in vertical layer were significant negative correlation,especially there was more significant negative correlation of alfalfa after firing treatment in soil depth between 0-200 cm. According to the plant growth curve and the distribution law of soil water,comparing with cutting the front stubble alfalfa,the firing treatment was good for alfalfa＇s earlier and faster growing in the case of sufficient soil water.