The Effect Of Root Cutting On Growth And Development Of Rice

The effect of different degree root cutting when transplanting on growth and yield of rice were studied, with taking the production and the climatic conditions of middle Jilin Province regions as the foundation. Using Song-122, the experiments were carried out at experimental base of Jilin Agricultural University from 2004-2005.The roots were artificially cut at transplanting stage: A0 (when transplanting, seedling roots were completely cut); A0.5 (leaving seedling roots length was 0.5cm); A1 (leaving seedling roots length was 1cm); A1.5 (leaving seedling roots length was 1.5cm); A2 (leaving seedling roots length was 2cm); ck (seedling roots were not cut).After transplanting rice seedlings in the field, and waiting to turn green rice of seedlings, sample plants were marked card and investigated morphological characters every 2 weeks; Chlorophyll content was measured every 2 weeks too. In rice main growth period, the dry matter accumulation all rice organs were measured. Roots bleeding sap were measured at late tillering, heading and milky stages. Took system soil block and measured the root system distribution at ripening period.Net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂concentration (Ci) and transpiration rate were measured at grain filling stage. After harvest, yield components were analyzed. The results showed:After mildly root cutting ( A1, A1.5, A2 ) , the date of tillering, heading, full heading and mature period were brought forward, and after serious root cutting (A0, A0.5) the date of these stages were delayed, but the difference among these treatments were not distinct. As a whole, the mature time of A1.5, A2 was 3-5days earlier and A0, A0.5 was 2-4days later.The tillering formation in early stage was restrained of root cutting treatments, the greater the root was cut, less tillers the rice plant had. Meanwhile, partial tillers occurred slowly, period of efficient tillering was prolonged, died tillers were fewer and there no evident difference in tillers number between root cutting treatment and ck in later period. Rice plant height in different growth stages and leaf area of root cutting treatments in both growth early stage and mid-stage were restrained, but root cutting can make rice maintain higher leaf area index (LAI) and functional blades in later stage. Except for booting stage, root cutting can improve Chlorophyll content of rice leaves, but the difference between root cutting treatments and ck was not distinct. In different growth stages, aboveground dry matter accumulation of rice was lowered due to root cutting, but simulation of dry matter on panicle during heading stage and grain filling stage was increased and the ratio of dry matter of A0, A0.5 and A2 became lower than ck during mature stage, and maybe this was the one reason of leading the yield...