Comparative Studies On The Effects Of Several New Plant Growth Regulators On Nitrogen Metabolism And Photosynthesis Characters Of Rice

This paper studied the effects of several new plant growth regulators on rice nitrogen metabolism, grain and brown rice protein contents, grain protein yield and photosynthesis characters which served as the theoretical basis for exploiting new plant growth regulators (PGR) and popularizing new technology of increasing rice protein content. Two new plant growth regulators having significant effects were selected from them. The results were shown as follows:1. Applying plant growth regulators could delay dropping chlorophyll content to some extent. In milk stage and maturity stage, Chlorophyll content of PGR4 treatment was the highest and had a minimum magnitude of decrease, and PGR3 treatment took second place. Net photosynthetic rate of PGR treatments were higher than that of CK treatment. Net photosynthetic rate of PGR4 treatment was the highest and PGR3 treatment took second place. CO: concentrations among cells of PGR treatments were lower than that of CK treatment, that of PGR4 treatment was the lowest and PGR3 treatment took second place.2. Contents of total N and protein N in the functional leaves and stem-sheaths of early and late rice were decreased gradually with progressing stage of rice growth. Magnitudes of decrease of total N content and protein N content in functional leaves and stem-sheaths of PGR treatments in early and late rice were higher than that of CK treatment. These magnitudes of decrease in PGR4 treatment were the highest and PGR3 treatment took second place. In early milk stage, total N content and protein N content in functional leaves and stem-sheaths of PGR treatments in early and late rice were lower than that of CK treatment, but in late milk stage, there were higher than that of CK treatment, because dropping speed of them were larger than that of CK treatment after milk stage.3. Research results of the experiments in early and late rice showed that the differences of nitrate reductase activities (NRA), glutamine synthetase activities (GSA) and glutamine transferase activities (GTA) in functional leaves and GSA, GTA in grain among PGR treatments were large in early milk stage. Then these differences grew smaller and smaller with progressing stage of rice growth. These key enzyme activities of PGR treatments were higher than that of CK treatment. These key enzyme activities of PGR4 treatment was the strongest and PGR3 treatment took second place. In early milk stage, the differences of protease activities in rice functional leaves among PGR treatments were smaller in early stage, but there were larger in middle and late stages. Protease activities of PGR treatments were stronger than that of CK treatment and PGR4 treatment took the strongest, PGR3 treatment took second place.4. Research results of the experiments in early and late rice showed that total N contentand protein N content of PGR treatments in five growth stages were higher than that of CK treatment; In ripe stage, both total N content and protein N content in grain of early and late rice were in the order of PGR4>PGR3>PGR2>PGR1>PGR5>CK. Total N content and protein N content in brown rice of early and late rice showed the same tendency. Of all these treatments, total N content and protein N content in brown rice of PGR4 treatment was the highest: protein N content of early brown rice was increased by 1.41 g-kg"1 compared with CK treatment and protein content was increased by 8.81 g-kg"1; protein N content of late brown rice was increased by 0.97 g-kg*1 compared with CK treatment and protein content was increased by 6.06 g-kg'1. PGR3 treatment took second place: protein N content of early brown .rice was increased by 1.37 g-kg"1 compared with CK treatment and protein content was increased by 8.56 g-kg"1; protein N content of late brown rice was increased by 0.58 g-kg"'compared with CK treatment and protein content was increased by 3.63 g-kg"1. Protein yields of grain in early and late rice were higher in every PGR treatment than in CK treatment. The protein yields of PGR4 treatment was the highest, the p...