2.营养生长期对环境条件的要求蔬菜种子一旦发芽便开始了营养生长。营养器官是指根、茎、叶,这里只讨论根系及叶片的生长特性及与环境条件的关系。 (1)根系的生长特性:根的主要功能是吸收水份及矿质营养,蔬菜的生长发育需大量的水份和矿质营养,它们都是由根从土壤中吸收而来。根的吸收能力,主要决定于根系的表面积大小,根总表面积的扩大是依靠根的分枝,伸长及根毛的发生。根的分枝:根的吸收功能各个部位不同,较老的木栓化的根也能吸水,但吸水量很小,主要的吸收功能在新生的幼嫩根区,因此都要求蔬菜作物有能强烈分枝和大量产 2. Vegetative Requirements for Environmental Conditions Vegetative growth begins once germination of vegetable seeds occurs. Vegetative organs refer to the roots, stems and leaves, where only the growth characteristics of the root system and the leaves are discussed and their relationship to environmental conditions. (1) root growth characteristics: The main function of the root is to absorb water and mineral nutrition, the growth and development of vegetables require a lot of water and mineral nutrition, which are absorbed from the roots by the roots. The absorptive capacity of the root depends mainly on the surface area of ​​the root system. The expansion of the total root surface area depends on the branching, elongation and root hairs of the root. Roots branches: the absorption of different parts of the roots of different parts of the older corked roots can absorb water, but the amount of water absorption is small, the main absorption function in the nascent young root zone, and therefore require vegetable crops can Strong branches and mass production