The role of time of emergence in determining the growth of individual plants in swards of subterranean clover (Trifolium subterraneum L.)
The role of time of emergence in determining the growth of individual plants in swards of subterranean clover (Trifolium subterraneum L.)
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出苗时间在决定地下三叶草（Trifolium subterraneum L.）草丛中个体植物生长中的作用
DOI：
10.1071/ar9630628
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发表时间：
1963
影响因子：
1.9
通讯作者：
G. Wilkinson
中科院分区：
文献类型：
--
作者：
J. Black;G. Wilkinson
通过试验，分别评价了出苗期前生长速率和出苗期竞争环境对地下三叶草单株后续生长的影响。在阿德莱德的韦特农业研究所，巴克斯沼泽品种的草被种植在大种子箱里。采用四种不同的播种处理，在棋盘格中交替播种的植株被推迟了0、2、4和8天。分别记录各株的出苗期和末干重。较早播种和较晚播种的植物在出苗时间上有相当大的重叠。因此，通过比较各处理早播和晚播植物出苗日单株产量的单独回归，可以证明，在同一草地上同一天出苗的植物，在相同的竞争环境中，具有非常不同的出苗前生长速率，其后续生长基本上相同。换句话说，在不存在差异化竞争效应的情况下，未发现出现前增长率对随后增长的影响。另一方面，单株最终干重与出苗期密切相关。延迟出苗5天导致最终产量减少约50%，延迟8或9天至少减少75%。鉴于苗期前生长速度本身的影响微不足道，这种减少完全是由于来自已苗期植物的竞争日益激烈。尽管出现模式差异很大，但所有草的总产量非常相似，表明植物之间在利用有效生长因子方面几乎完全补偿。
An experiment was carried out which enabled a separate assessment to be made of the influence of, firstly, pre-emergence growth rate, and secondly, the competitive environment at emergence on the subsequent growth of individual plants of subterranean clover. Swards of the Bacchus Marsh variety were grown in large seed boxes at the Waite Agricultural Research Institute, Adelaide. Four different sowing treatments were applied whereby the sowing of alternate plants in a checkerboard grid was delayed by 0, 2, 4, and 8 days. Emergence date and final dry weight were recorded individually for each plant in the experimental swards. There was considerable overlap in emergence times between the earlier and the later-sown plants. Consequently by a comparison of the separate regressions for earlier and later-sown plants of yield per plant on day of emergence for each treatment, it could be demonstrated that plants with very different pre-emergence growth rates but emerging on the same day in the same sward, and hence into the same competitive environment, gave essentially the same subsequent growth. In other words, in the absence of differential competitive effects, there was no detectable influence of pre-emergence growth rate on subsequent growth. On the other hand, the final dry weights of individual plants were very strongly related to day of emergence. A delay in emergence of 5 days brought about a reduction in final yield of about 50%, and a delay of 8 or 9 days of at least 75%. In view of the negligible influence of pre-emergence growth rate, per se, this reduction is attributable solely to the increased severity of competition from plants already emerged. In spite of the wide variation in emergence patterns, the total yields of all swards were very similar, indicating an almost complete compensation between plants in the utilization of available growth factors.