| Kudzu is an economic plant with very good potential of production, It also a very good plant for water and soil conservation purposes, A lot of research prove that Kudzu planted can get very good economic and ecological benefit. There are serious soil erosion and desertification in our country; it is a good choice to use Kudzu to solve these problems according to local situation, and it is also very important to develop sustainable agriculture in arid or semiarid regions in our country. For the purpose to know characters of the plant more and use it more efficient, to do some research about its physiology and cultivation is very necessary, and photosynthesis is an important part of physiology, so study on Kudzu's photosynthesis is important and necessary. Pot culture experiment was conducted to study Kudzu's photosynthetic characteristics by TPS-1 photosynthetic apparatus from pp-systems Company of England,The results show that:1. The photosynthetic characteristics of Kudzu are different in different growth periods, and every growth period has its own central limiting factor. In leafing date, diurnal variation in the photosynthetic rate of Kudzu Yao (Pueraria thomsonii Benth.) was a slow decline process but the photosynthetic rate of Kudzu Fen (Pueraria lobata (Willd.)Ohwi) had a little midday depression. The daily averages of photosynthetic rate is in a low level in this period, the central limiting factors in this period are internal factors of plant such as growth period and leaf age. In growing period, two types of Kudzu's diurnal variation in photosynthetic rate were"twin-peaked"curves,the main reasons of midday depression were strong light and high temperature at noontime but not the limiting of the plant stomata. In period of prosperityâ… , Kudzu's diurnal variation in photosynthetic rate were"twin-peaked"curves, but in this period the main reason of midday depression was the limiting of the plant stomata according to other photosynthetic parameters. In period of prosperityâ…¡, diurnal variation in photosynthetic rate were also"twin-peaked"curves, but other photosynthetic parameter didn't have the synchronous changes, and photosynthetic rate at midday depression time kept in a high level, so we have to do further research to find the reasons of this phenomena. In period of downfall, diurnal variation in photosynthetic rate were also"twin-peaked"curves, but daily averages of photosynthetic rate is much lower than periods before, it is because of internal factors of plant, the leaves had been downfall and the photosynthesis ability of them had been declined.2. A positive exponential correlation x = aebybetween photosynthetic rate(y) of Kudzu leaves and light intensity(x) was observed under different soil water contents. According to analysis result of software SPSS, Soil water contents had a significant effect on photosynthetic rate, but in the same Soil water content, two types of Kudzu's photosynthetic rates have no significant differences. The suitable soil water content is about 20%, if Soil water content is less than 10%, the photosynthesis of Kudzu will be stagnated, the leaves became wilt, some of leaves even drought up and died. Soil water contents also had a significant effect on transpiration rate and stomatal conductance, but in the some soil water content, different leaves in some position may have different transpiration rate and stomatal conductance, it's because the internal factors of plant.3. In suitable soil water content,the connection between photosynthetic rate(y) of Kudzu leaves and light intensity(x) also is x = aeby.In different leave positions the light saturation points were different, And when the light intensity was higher than the light saturation point, photosynthetic rate of the young leaves, the mature leaves and the old leaves were difference, the higher ones maybe two to six times higher than the lower ones. The light compensation point of kudzu leaves is about 30-40μmolï¹’m-2ï¹’s-1. The transpiration rate and stomatal conductance of young leaves were much lower than mature ones, it may be the reason of difference in photosynthetic rate between them.4. Nitrogen fertilizer had a significant effect on photosynthetic rate of Kudzu, but the effect of phosphate fertilizer doesn't significant, and two kinds of fertilizer don't have interaction effect. Salt stress has a significant effect on Kudzu's growth, the higher salt concentration is, the serious effect is, even cause death. According to the great effect of salt stress, we can estimate that salt stress also has a serious limit to the photosynthesis of Kudzu. After Kudzu planted for two years, soil organic matter has a significant increase。... |
