ABSTRACT

Analyses of New Zealand farm systems require estimates of herbage yield and quality. These are available for perennial ryegrass and white clover pastures but not for other common pasture species. We used five lucerne datasets to derive functional relationships between growth rate and temperature. This required three functions to account for partitioning in lucerne between spring and autumn and differences between seedling and regrowth crops. The maximum mean daily growth rate of 206 ± 5.95 kg DM/ha/d occurred with full canopy cover at mean air temperatures between 15°C and 22°C. This represents the upper end of the temperature range available. The relationship was summarised into a matrix that could be incorporated into existing forage forecasters for farm system analyses. Alternatively, a simplified model assessed growth rate in relation to thermal time. This showed after 140°Cd accumulated from 1 July, lucerne initiated spring growth at 11.9 kg DM/ha/°Cd until mid-January and then decreased to 6.7 kg DM/ha/°Cd from mid-January to 30 June for fully irrigated crops. An exponential heightchron relationship was also calculated to estimate crop height based on the thermal time required per mm as photoperiod changed. This relationship allows lucerne quality to be predicted from the leaf:stem ratio.

摘要

新西兰农场系统的分析需要估计牧草产量和质量。这些可用于多年生黑麦草和白三叶草牧场，但不适用于其他常见的牧场物种。我们使用五个卢塞恩数据集来推导生长速率和温度之间的函数关系。这需要三个函数来解释春季和秋季之间苜蓿的分配以及幼苗和再生作物之间的差异。在平均气温介于 15°C 和 22°C 之间的全冠层覆盖情况下，最大平均日增长率为 206 ± 5.95 kg DM/ha/d。这代表了可用温度范围的上限。这种关系被总结成一个矩阵，可以并入现有的草料预报器以进行农场系统分析。或者，一个简化的模型评估了与热时间相关的增长率。这表明在从 7 月 1 日累积 140°Cd 之后，苜蓿在 1 月中旬之前以 11.9 kg DM/ha/°Cd 开始春季生长，然后在 1 月中旬至 6 月 30 日期间降至 6.7 kg DM/ha/°Cd，完全灌溉庄稼。还计算了指数高度时间关系，以根据光周期变化时每毫米所需的热时间来估计作物高度。这种关系允许从叶：茎比预测紫花苜蓿质量。还计算了指数高度时间关系，以根据光周期变化时每毫米所需的热时间来估计作物高度。这种关系允许从叶：茎比预测紫花苜蓿质量。还计算了指数高度时间关系，以根据光周期变化时每毫米所需的热时间来估计作物高度。这种关系允许从叶：茎比预测紫花苜蓿质量。