Effects of Tiller-inhibitor on Growth and Yield Formation of Early Sup er Hybrid Rice Jinyou 458

The effects of the tiller-inhibitor(TI) on th e growth and yield formation of the early super hybrid rice Jinyou 458 were stud ied.Compared with the check(no TI sprayed),the TI treatment(1.5 kg/hm2 of TI sprayed at the SN-n stage or critical leaf stage of effective tillers; N=No.of leaves on main culm,n=No.of elongated internodes) reduced invalid an d smaller tillers resulting in a marked increase of the proportion of the big ef fective tillers with 4 or more leaves at the maximal tiller stage,increased the panicle length,spikelets per panicle,spikelet density,secondary branches and the spikelets and seed setting rate on them,plant height and LAI and biomass i n the middle and late growing stages,strengthened the photosynthetic capacity b y increasing leaf temperature of the top three leaves and improving the populati on light transmission at the booting stage and raising the leaf SPAD values,but it elongated the internodes of plants and decreased the stem thickness.Therefo re,the TI treatment finally increased the grain yield for a coordinative improv ement in such characteristics as the panicle-bearing tiller rate,productive pa nicles,spikelets per panicle,seed setting rate and grain weight.