Super-high yielding characteristics and regulation techniques in Ⅱ youhangl using as ratoon rice cultivar

6.7 hm2 demonstration areas of super-high yielding ratoon rice were established in Youxi County of Fujian Province.The average yields from 2003 to 2005 were 12 375 kg·hm-2 in main cropping season and 7907 kg·hm-2 in ratoon rice.Output investigation and test result analysis indicated that:①The output of ratoon rice and the quantity of total spikelets in the per m2 area display extremely remarkable relation, in main rice, spikelets per spike was related best to yield; in ratoon rice, the spikes per m2 was related best to yield.②To realize superhigh yielding byⅡyouhangl, the key in main cropping season was how to cultivate further big spike on the basis of adequate spike and breaked through the bottleneck of total spikelets per m2, forms 45000—50000 spikes per m2 of storehouse capacity; the key for ratoon rice was boosting germination rate of auxiliary bud, forming more spikes than that of main rice and offsetting shortage of small spikes by using more spikes, forms 35000 spikelets per m2 of storehouse capacity.③The main techniques for super-high yielding were:optimized growing period, excavated latent productivity of climate resources, sowing and planting early in order to prolong vegetative growth period, cultivating rice in ridge bed with intermittent furrow irrigation, advancing fertilizer practice, maintaining soil moisture and aeration, cultivating developed shape and high functional root system; cultivating main rice well, improving vitality of root system at later stage, leaving higher rice stubble and dressing heavy fertilizer to promote buds and tillers of ratoon rice.