我国黄河以北的广大地区,每逢播种时节,常遇严重干旱,不能及时播种。有的免强下种,也因土壤内缺少水份,不能及时发芽,使幼苗生长受到严重影响。怎么办呢?这就需要利用有限的水分进行播种。为了做到节约用水,就必须了解种子萌发时对水分的需要状况。种子在成熟后,离开母体之时,都带着一份营养成份齐备而数量充足的“食粮”,把它们贮存在胚乳或子叶中,以备种胚生长时的需要。在种胚萌发时,必须先用水将这些“食粮”变成可溶性物质。同时,还要用水将其中的高分子化合物如淀粉、蛋白质、脂肪等,分解为低分子化合物如糖、氨基酸及脂肪酸等。这里水既充当溶剂,又作为胚同化过程的参与者。这就是种子萌发时,水分的用处。种子萌发时,需要多少水分呢?实验证明, In the vast area north of the Yellow River in our country, there is often a serious drought whenever sowing, which can not be sown in time. Some kinds of strong-free, but also because of the lack of water in the soil, can not be germinated in time, the seedling growth is seriously affected. What to do? This requires the use of limited moisture for planting. In order to achieve water conservation, we must understand the seed germination of the water needs of the situation. After maturity, the seed leaves the mother’s body with a well-stocked “food” in sufficient quantities and stored in the endosperm or cotyledons to prepare for the growth of the embryo. During seed germination, these “foods” must first be made water soluble. At the same time, but also the water will be one of the polymer compounds such as starch, protein, fat, broken down into low molecular weight compounds such as sugar, amino acids and fatty acids. Water acts both as a solvent and as a participant in the process of embryo assimilation. This is the seed germination, the use of water. Seed germination, how much moisture it needs? Experiments show that,