EFFECT OF NITROGENOUS FERTILIZER ON FINAL PARTITIONING OF THE ~(14)C FED BEFORE AND AFTER FLOWERING OF PADDY RICE GROWN AT DIFFERENT ALTITUDE LOCALITIES
Li Cunxiu, Lin Dehui (Kunming Institute of Botany, Academia Sinica, Kunming 650201)
The paddy rice in the field experiment, grown at three different altitude localities, viz. Yuanjiang (north tropic type about 400 m altitude), Yuxi ( middle subtropics type about 1600 m altitude) and Dali ( north subtropics type about 2000 m altitude) in Yunnan province in 1988, had been fed with the 14C to the paddy rice to have been treated with different levels of nitrogenous fertilizer, during the booting and grain filliag stage, respectively. All the samples of the aerial plant parts had been collected at the yellow ripe stage, and divided into vegetative mass (included leaves, leaf sheath, stem, ear axis and pedicel and its dicback parts) , rice and chaff, and then determined dry weight and specific activity of the 14C, respectively, and that the percentages of the 14 C in each part had been calculated by dry wcigth. The main results arc as follows: 1. Final partitionings of the 14C fed at the booting stage occur mainly in the vegetative mass and the chaff. The 14C-perccn(agc of final partitioning in the vege- tative mass is positive correlation (r= 0.9449) to the percentage of final vegetative mass made up total dry weight, the chaff competes with the vegetative mass for the assimilate at the booting stage, final partitioning ratio of the 14C in the chaff is contrary to the partitioning ratio in the vegetative mass, the nitrogen application creates larger vegetative mass; the 14 C-percentage of final partitioning in the vegetative mass is higher, too. When the paddy rice grown at high altitude-localities compared to those grown at low altitude-localities, under the same way of nitrogen application, the ratio of the 14C in the vegetative mass is higher, too, because there is higher percentage in the vegetative mass. 2. Because the ability to assemble carbohydrate has not yet formed at the booting stage, final partitioning in rice of the 14C fed in this stage may be considered that assimilate accumulated in the vegetative mass before flowering had been rcpartitioning towards the grain after flowering. The final partitioning of the 14C fed to paddy rice at the booting stage, grown at low heat localities, is positive correlation with seed-setting numbers per unit leaf area at the grain filling stage, but the above described relations weaken in the paddy rice grown at the planting site of high altitude, and final partitioning ratio of the 14C in rice increases with the increase in ratio of ear manuring. It will be shown that when the grain of paddy rice assembles carbohydrate assimilated before flowering at high altitude-localities, it is subjected to combined regulation of the sink size and activity. 3. Final partitionings of the 14C fed at the grain filling stage occur mainly in rice, the percentages of final partitioning in rice depend mainly on seed-setting numbers (r= 0.9503) per unit leaf area at this time. The application of nitrogenous fertilizer increased in final percentage of the 14C in the vegetativ mass, the larger the ear manuring ratio and the higher the altitude are, the larger the final percentages of the 14C occure in the vegetative mass.