| We conducted a series of field experiments in 2003 at Tongzhou Distinct, Water-circulation and Modern Water-saving Technology Experimental Field, Institute Geography and Resource of Science, Chinese Academy of Science. The study focused on radish growth and development, the photosynthetic parameters (net photosynthetic rate, stomotal conduction, CO2 concentration of the intere-cell, transpiration rate et. al. ) of the radish leaves, the key enzyme in the photosynthesis-Rubisco, the physiology indexes of the radish (the chlorophyl content, the content of the malondiadehyde in the leaves, the content of the solubility glucide and the vitamin C in the root of the radish ), the leaf water potential and the process of the water-consuming under the conditions of drip irrigation and flood irrigation. From the experiment results, during the growth of the autumn-winter radish in Huabei Plain, it could be concluded that:(1). Different irrigation treatments had a certain impact on radish growth. Under the conditions of drip irrigation, the average growth rate, the net assimilation rate, the ratio of the root weight and crown weight were superior to the corresponding growth index under the condition of flood irrigation. Moreover, the market qualities of radish with drip irrigation excel the ones with flood irrigation.(2). Different irrigation treatments had a certain impact on the photosynthetic rate of the radish leaves. The net photosynthetic rate with drip irrigation is always higher than one with flood irrigation during the growth. Based on the changing of plant physiological parameters related with the photosynthesis, the results showed that the transpiration rate rose, the stomatal conduction fell, the CO2 concentration of the intere-cell lessened, and the vapor pressure deficit of leave increased under the condition of flood irrigation. All the above changes were not propitious to the leaf photosynthesis.(3). Different irrigation treatments had a certain impact on the Rubisco enzyme closely related to the photosynthetic rate of the radish leaves. There are differences in the Rubisco activity and Rubisco content between different irrigations. Under the treatment of drip irrigation, the photosynthesis rate is very significantly correlative to initial Rubisco activity, total Rubisco activity and Rubisco content, which is always higher than those under the treatment of flood irrigation. Analyzing the relativity of the photosynthetic rate and the Rubisco content, we can see that the correlation coefficient in drip irrigation was higher than that in flood irrigation.(4). Different irrigation treatments had a certain impact on the chlorophyll content, the content of the malondiadehyde in the leaves, thecontent of the solubility glucide and the vitamin C in the root of theradish. The chlorophyll content of the radish leaves in drip irrigation is higher than that in flood irrigation before the harvest. And the content started to fall during the harvest. The treatment of flood irrigation could prevent the leaves from getting senescence during the harvest. The content of the malondiadehyde in the leaves in flood irrigation is obviously lower than that in drip irrigation. However, these factors were harmful to the quality of the radish root. The contents of the soluble glucide and the vitamin C in the root of the radish under the condition of drip irrigation were higher than those under flood irrigation.(5).Different treatments had no significant impact on the daytime changes of the leaf potential. No matter what the drip irrigation and flood irrigation, the peak of the leaf potential in both of them at 7:00 a.m., and the lowest at 13:00 p.m.. Seeing from the amount of the water consuming, daytime average value and the percentage both in drip and flood irrigation, we could conclude that there was no significant effect on the characteristic of the water consuming in the period of the radish growth under the condition of different irrigations. The irrigating amount in drip irrigation was 291. |
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