梨枣花果期耗水规律及其与茎直径变化的相关分析

设置4个水分处理,研究了4年生梨枣2010年及2011年花果期不同供水条件下土壤水分动态和耗水规律,分析了梨枣日耗水量与茎直径变化间的相关性,建立回归模型.结果表明:(1)2a内各处理梨枣耗水量随土壤供水量的增加而增大,其日耗水量最大值均出现在灌水后1周内；各处理果实膨大期日耗水强度大于开花坐果期.(2)2a内各处理茎直径日变化平均值(MTD)、茎直径日最大值(MXTD)均符合Logistic函数关系,MXTD与MTD在表征梨枣茎秆生长规律方面效果一致,各处理茎直径变化指标(MTD、MXTD)增长率因水分处理的不同而存在差异.(3)高水分(T1处理)条件下茎直径变化指标(MTD、MXTD、MDS(茎直径日最大收缩量)、DG(茎直径日生长量))在表征枣树耗水状况方面不敏感；在低水分(T4处理)条件下,日耗水量与茎直径日最大收缩量(MDS)相关系数较其他3个茎直径变化指标(MTD、MXTD、DG)高且达极显著水平,说明MDS能够更好的表征低水分处理的梨枣耗水规律.在此基础上建立耗水量与茎直径变化回归模型,为评价梨枣耗水状况提供依据.

Water consumption of pear jujube trees (Ziziphus jujuba Mill.) and its correlation with trunk diameter during flowering and fruit development periods

Pear jujube (Ziziphus jujuba Mill.) as a common tree crop in the Loess Plateau region ofChina, but its ecological and economic benefits have failed to be fully realized because of the shortage of water resources. Therefore, improving jujube yield and water use efficiency are key goals. Studies of the water deficit index and water consumption rules can help to design more optimal irrigation systems and improve water use efficiency. In 2010 and 2011, we studied the water consumption of 4-year-old jujube plants subjected to one of four soil water treatments during their flowering and fruit development periods. We analyzed the correlation of water consumption to variation in trunk diameter and established a regression model. Our goal was to determine how pear jujube stem diameter responded to water conditions during the flowering and fruit development periods to determine a suitable water deficit index to use in building irrigation systems. The flowering and fruit development periods of pear jujube are critical water demand periods. Because these two processes define the main period of reproductive growth, they determine the quantity, volume, weight, and yield of fruit. Stem diameter change indexes included daily mean trunk diameter (MTD), daily maximum trunk diameter (MXTD), maximum daily shrinkage in trunk diameter (MDS), and daily growth of stem diameter (DG). The results indicated that (1) the tree water use increased with an increase in soil water content. Regardless of the treatment differences in soil water conditions, the maximum daily water use all occurred during the week following irrigation, and water consumption during the fruit expansion stage was greater than in flowering and fruit set stages. (2) Two years of experimental data proved that the logistic function could precisely express the changes in MTD and MXTD in the critical water demand periods of jujube, so these two indexes were equivalent in terms of assessing jujube trunk diameter growth during the study period, even though the growth rate varied annually and among treatments. (3) Under the high-water treatment, the indices derived from the trunk diameter (MTD, MXTD, MDS, and DG) were not sensitive to water consumption, while in the low-water treatment, MDS had a highly significant correlation with daily water use compared with the other indexes, indicating its potential as an indicator of jujube water consumption under water deficit conditions. The regression model between water consumption and trunk diameter that we established can be used to analyze the sensitivity of stem diameter variation to water deficit and to detect the water consumption status of pear jujube trees.