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为了提出一种合理的数学分析方法确定“巨峰”葡萄结果期开始灌溉的精确土壤水势阈值.针对以土壤水势实时监测及果实粒径无损测量、数据拟合等方法获取的果实膨大速率关于土壤水势的离散数据曲线,采用基于Matlab编程的3次样条插值法对所形成的散点图进行曲线平滑化处理,考察一阶求导后曲线的斜率变化并结合新梢生长等指标的显著性差异进行综合分析,确定了果实幼果期、第1次快速膨大期、转色期各生长阶段划分的临界值和对应时期开始灌溉的土壤水势阈值.将“巨峰”葡萄结果期的果实生长划分为急速膨大、快速膨大、缓慢膨大、收缩4个阶段并确定了幼果期、果实第1次快速膨大期、转色期开始灌溉的土壤水势阈值分别为-11.64、-14.86和21.00 kPa,可为指导果树的水分管理提供关键参数,为农业精准灌溉技术中土壤水势阈值的研究奠定了理论依据.“,”The objective is to Present a reasonable mathematical analysis method to determine the precise soil water potential threshold for starting irrigating in the fruiting stage of“Kyoho”grapevine.After using the methods of real-time monitoring soil water potential, non-destructive measurement of fruit size and collecting the data that formed the discrete curve of the relationship between the berry enlargement rate and soil water potential,the figures are given a scatter plot curve smoothing processing via the cubic spline interpolation method based on Matlab software,and then they are inspected through the changes of derivative curve slope.Finally, the significant differences between the growth of shoots indicators are conducted by comprehensive analysis.The critical values to distinguish the different stages of the period of berry set,berry first rapid growth period and veraison are determined,as well as the soil water potential thresholds to start irrigating at the corresponding stages of“Kyoho”grapevine.The development of berries during the fruiting stage in“Kyoho”grapevine are divided into four phases,including high speed growth phase,rapid growth phase,slow growth phase and shrinking phase.In addition to this, the soil water potential thresholds to start irrigating during the period of berry set,berry first rapid growth period and veraison are determined as -11.64,-14.86 and 21.00 kPa respectively,which can be used to guide the water management in the cultivation of fruit and provide key parameters and theoretical basis for the research in precision irrigation technology upon soil water potential threshold.