水稻谷粒成熟期往往会碰到不稳定的气候(较低的昼夜平均温度和降雨量),导致子粒积累减弱和质量下降,结果子粒不饱满,产量降低。充分供应水稻所需营养元素,是使水稻提早成熟和增加产量的好方法。用氮肥溶液作根外追肥可使营养器官产生的物质加速流入子粒,采用矿质肥(硝酸铵、尿素、过磷酸钙)加入微量除莠剂——2,4—D,这叫“雪尼康采”法。这种方法与收割前喷氯化锰使大多数稻叶迅速死亡的方法不同。它是使稻叶象自然衰老那样缓慢地枯死。其中2,4—D的作用在于加强氮素毒性的消除并使氮素加速渗透到作物的叶内去。目前,根外追肥广泛利用尿素,因为它比较容易渗透到植物组织内,尿素喷洒后30分钟就可渗透到谷粒中去。在叶内尿素酶的作用下,迅速 Rice grain maturation often encounter unstable climate (lower average day-night temperature and rainfall), leading to weakening of grain accumulation and quality decline, the result is not full grain, yield reduction. Full supply of nutrients needed by rice is a good way to make rice mature earlier and increase yield. Nitrogen fertilizer solution for root top dressing can accelerate the flow of substances produced by vegetative organs into the grain, the use of mineral fertilizers (ammonium nitrate, urea, superphosphate) adding trace amounts of herbicide - 2,4-D, called “ ”law. This method is different from the rapid death of most rice leaves with manganese chloride before harvest. It is to make the rice leaves die slowly as they naturally do. The role of 2,4-D is to strengthen the elimination of nitrogen toxicity and to accelerate the infiltration of nitrogen into the leaves of the crop. At present, urea is widely used in top dressing on the root because it penetrates into the plant tissue more easily and penetrates into the grain within 30 minutes after the urea is sprayed. In the leaves of urease, rapidly