Modeling Freezing Injury in Alfalfa to Calculate Forage Yield: II. Model Validation and Example Simulations
Modeling Freezing Injury in Alfalfa to Calculate Forage Yield: II. Model Validation and Example Simulations
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DOI：
10.2134/agronj1998.00021962009000050020x
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发表时间：
1998-09
期刊：
影响因子：
2.1
通讯作者：
V. Kanneganti;W. Bland;D. Undersander
中科院分区：
文献类型：
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作者：
V. Kanneganti;W. Bland;D. Undersander
冻害可导致紫花苜蓿(Medicago sativa L.)大面积减产。在寒冷的气候中暴露在严冬中。紫花苜蓿模型必须以累积的方式模拟冻害效应，以便能够准确地计算出一种作物多年的牧草干物质(DM)产量。ALFACOLD是在Alsim 1(Level 2)紫花苜蓿模型中集成了耐寒、秋眠和冻害等功能而开发的一个紫花苜蓿模拟模型。ALFACOLD模型每天计算牧草产量，同时模拟同一作物多年的冻害。这项研究的目的是测试ALFACOLD模型计算田间牧草干物质产量的能力。在威斯康星州的两个地点，对39个品种在两年内播种，并在播种后三年的四割制度下管理，根据测量的牧草产量对该模型进行测试。ALFACOLD模型计算的年牧草干物质产量在测产的12%以内，而ALSIM模型的误差为35%。田间测量的单季产量(n=874)与相应的ALFACOLD计算的产量的回归表明，70%的测得牧草产量的变异性可以用该模型解释。收获1、2和3的DM产量的实测值和计算值之间的平均差异为<；7%，但该模型高估了第四茬产量38%。ALFACOLD模型计算了所有地点、品种、年份和产量的平均产量，平均标准偏差为600公斤ha-1产量。
Freezing injury can cause extensive yield loss in alfalfa (Medicago sativa L.) exposed to severe winters in cold climates. Alfalfa models must simulate freezing injury effects in a cumulative way, so that forage dry matter (DM) yield can be accurately calculated during multiple years of a crop. A companion paper presents ALFACOLD, an alfalfa simulation model developed by integrating functions of cold tolerance, fall dormancy, and freezing injury into the ALSIM 1 (Level 2) alfalfa model. The ALFACOLD model calculates forage yield on a daily basis, while simulating freezing injury across multiple years of the same crop. The objective of this study was to test the ALFACOLD model's ability to calculate field-measured forage DM yield. The model was tested against measured forage yield from 39 cultivars seeded in two years and managed under a 4-cut system for 3 yr after the seeding year at two sites in Wisconsin. Averaged across the sites, cultivars, and years, the ALFACOLD model calculated annual forage DM yield to within 12% of the measured yield, compared with an error of 35% with the ALSIM modeL A regression of field-measured yield of individual harvests (n = 874) on the corresponding ALFACOLD calculated yield indicated that 70% of the measured variability in forage yield was explained by the model. The average difference between measured and calculated DM yield for Harvests 1, 2, and 3 was <7%, but the model overcalculated fourth-cut yield by 38%. Averaged across all sites, cultivars, years, and cuts, the ALFACOLD model calculated yield with an average SD of 600 kg ha -1 cut -1 .