玉米根系生长及向水性的模拟

SIMULATION OF GROWTH AND HYDROTROPISM OF MAIZE ROOTS

用面向对象的程序设计（ＯＯＰ）技术组建了玉米（Ｚｅａ ｍ ａｙｓ）根系生长的三维模型，并用该模型模拟了根系在不同土壤水分剖面以及有、无向地性响应时的生长过程，探讨了根系向水性产生的机制以及向水性与向地性之间的关系．模型中将根系前沿看作由根尖构成的群体，每个根尖都对其周围环境独自作出响应，其中只有少数能继续分支． 模拟结果显示，玉米根系各单根受局部水势的影响而以不同速率伸长，即可造成总体的向水性． 如果土壤剖面上的水势由下到上递减，由此引起的单根伸长速率的不均匀分布将使整个根系在总体上表现出收拢和一致向下的生长趋势，并导致下层的根量相对增加．根系的向地性虽能使上述趋势增强。

A three dimensional model simulating the formation of root system architecture of maize was designed using object oriented programming (OOP) techniques.The model has been used to simulate the growth of roots in contrasting water profiles with or without gravitropism,and the mechanism of hydrotropism of root system and its relationship with gravitropism has been studied. In this model,the frontier of root system was treated as a population of root tips,each member of which responded individually to its local environment,and only a few of them could branch.The results of simulation showed that hydrotropism of maize roots could arise through the control of the elongation rate of single root by its local soil water potential.The difference in growth rate caused by the gradient of water potential along the soil profile alone could cause the root system as a whole to grow predominantly downwards,resulting in a shift of root distribution towards deeper layers.Gravitropism enhanced the downward predominance of the growth of root system,but the mechanism was different from that of hydrotropism.