RESPONSES OF DRY-MATTER PRODUCTION AND PARTITIONING IN THE AERIAL PART OF RICE GROWN AT DIFFERENT ALTITUDE LOCALITIES TO TOP DRESSING WITH NITROGENOUS FERTILIZER
Li Cunxin, Lin Dehui (Kunming Institute of Botany, Academia Sinica, Kunming)
Under the stdies of physiological-ecological laws on high-yielding culture of rice (Oryza sativa L.) in the plateau in 1983-1985, we had made a comparison between dry-mailer production and partitioning after top dressing with nitrogenous fertilizer (urea) of rice, grown at three localities, i. e., Yuanjiang (dry-heal river valley about 400 m altitude) , Kunming (warm-cool plalcau lake-shore about 1900 m altitude) and Lijiang (cold-cool plateau area, about 2400 m altitude) in Yunnan province. The treatments of top drcssing, on the basis of 20 kg/mu urea applied as a basal dressing, were applied with 10 kg/mu urea at the young panicle differentiation, pikelet differentiation and reduetion division stage, (these stages of fertilizer application are briefly known as early, midele and late ear manuring) respectively. Each treatment was teplicated three: times. The main results, obtained are: as lollows. 1. At the yellow ripe stage, total dry-matter productions of rice applied middle and late ear manuring are relatively near and are: obviously higher than that applied early ear manuring at Yuanjiang; the dilterenees among three treatments are small at warm-cool Kunming, the order of differences is middlelalecarly ear manuring, but the order is earlyniiddlelate ear manuring at cold-cool Li-jiang. 2. The earlier the top dressing with nitrogenous fertilizer is, the larger are the leaf area index and the ratio of leaf dry weight making up total dry weight. The differences among three trcalmentsare relatively obvious at the cold-cool, high-altitude localities. 3. Before full heading, the earlier the top dressing with nitrogenous fertilizer is, the more is the amount of dry-matter produced at three localities, among various localities compared with one another, such case is even more markedly al the low-altitude localities. 4. During grain filling stage, the treatment of early ear manuring decreased in weight of secondary sink (stem+ leaf sheath) of rice grown al the low-heal and warm-cool localities, and more weight is decreased at the low-heal localities. The treatments of middle and late ear manuring increased in weight of secondary sink (stem 4+leaf sheath) of rice grown at the warm-cool localities, while the weight of them is decreased at the low-heat localities All the secondary sink of rice, without reference to early or late top dressing, increased the dry weight at cold-cool, high-altitude localities in the meantime, but the treatments of middle and late ear manuring increased more dry weight of the secondary sink. 5. In regards to the percentage of ear weight making up total weight at the yellow ripe stage, at low-heat and warm-cool localities, the percentages of rice applied early ear manuring are lower than those treated with middle and late ear manuring, and yet the percentages of rice treated with middle and late ear-manuring are conformable on the whole, at cold-cool localities, however, the earlier the lop dressing is, the higher is the percentage.