Study On Physiological Characteristic Of Photosynthesis In Water Culture Young Apple Seedling Under Partial Rootzone Drying

Water culture young apple seedlings (Malus demestica Borkh.W.Gala) were grown in ether a glasshouse(GH) or a controlled environment cabinet(CEC) to assess the effect of partial rootzone drying(PRD) > total root-zone stress(TRS) and no rootzone stress (CK) with ploythylene glycol (PEG6000) of physiological characteristic on photosynthesis .The results were as follows: Both in the GH and CEC, net photosynthesis rate (Pn) of PRD were lower than CK, but higher than TRS. In the GH, Pn of TRS was restrained under lower PAR than PRD and CK. The relationships between net photosynthesis rate (Pn) and stomatal conductance (Gs), Gs and transpiration (E), Pn and E are significant postive correlation, and T and Pn is significant negative correlation at P=0.01 level respectively. Because of lower Gs of TRS than CK and PRD, on the one hand the relationship between Gs and T is no significative correlation, on the other hand the relation between Pn and T is significant negative correlation. All of these tell us that high temperature of leaves maybe a important factor about lower Pn on TRS.In the CEC, there are no significative correlation between Pn and Gs of TRS and CK, however the relationship between Pn and GS is significative postive correlation at P=0.01. PRD is more sensitive to Gs than CK and PRD maybe tell us we can reach the best water use efficiency by it and we will have a more important question about how to regulate the degree of PRD needed to research in futureWhether in the GH or in the CEC, the contents of Car, Chi and the activity of SOD were decreased, the contents of MDA were increased on TRS. Keeping the contents of protective substance (Chi, Car and so on) and the activity of antioxidant enzymes ( SOD and so the like)etc may play key role in preventing the decline of the photosynthetic rate on PRD.