| The objective of the study was to select several simple, easy to operate and preselected indicators effected water use efficiency and speed up the process of dwarf-rootstock breeding in different apple rootstocks. The seedlings of fourteen 1-year-old apple dwarfing rootstocks(T337,M9,P22,Mark,SH1,F1,F2,F3,F4,M26,MM106,MM111,M7,M116) were used as test materials to determinate water use efficiency index such as morphological parameters and photosynthesis parameters in the field. Then several major indicators were selected by using correlation analysis and regression analysis to study water use efficiency of each leaf index characters. At the same time, for screening relatively strong drought resistance of good rootstocks, the difference of fourteen rootstocks water parameters were analyzed by PV technology, and drought resistance were comprehensively evaluated by anti membership function and cluster analysis. Finally, in order to explore the mechanism of drought resistance of rootstocks roots, taking two rootstock-scion combinations of 2-year-old apple seedlings Changfu 2/M9-T337 and Changfu 2/MM106 as test objects,a pot culture experiment was conducted in a rainproof shed to study the apple root morphological and physiological characteristics under moderate drought and well-watered conditions. The results were as follows:1,In the field, the study was to determinate water use efficiency index such as morphological, photosynthesis parameters of fourteen apple dwarfing rootstocks. And then several indicators were comprehensively analyzed. The results showed that: the sequence of δ13C of 14 apple rootstocks leaf were: M26>T337>M9>Mark>F1>F4> P22>F2>MM111> SH1>MM106>F3>M7>M116;correlation analysis showed that: δ13C and WUEi、Pn、Ci、SLW、gmin were significantly correlation; Stepwise regression analysis showed that the major factors caused the differences of rootstocks leaf δ13C were gmin and Ci. We could conclude that the differences of leaf δ13C were the common results of Pn、Ci、SLW、gmin and a series of morphological and physiological parameters, especially gmin and Ci were main influence factors. So, gmin and Ci were important indexes of high water use efficiency in apple rootstocks.2,The water parameters of different rootstocks were analyzed by PV technology and the results indicated that: not only the Ψstlp, Ψssat, RWCtlp, ROWCtlp, Va and εmax varied, but also the drought resistance was different in fourteen apple rootstocks. Through anti membership function and cluster analysis, the fourteen apple rootstocks were classified into three drought resistance groups. The strongest one included F4, M9 and P22;The stronger one included M26,Mark,T337,F1 and MM111;The relatively weak one included M116,F3,MM106,SH1, M7 and F2.3,The drought stress decreased root morphological characteristics and root hydraulic conductivity of two rootstock-scion combinations, and the reduction of dwarfing rootstock-scion combination Changfu 2 /M9-T337 was significantly less than semi-dwarfing rootstock-scion combination Changfu 2 /MM106; Under different water conditions, there were significant differences in root soluble sugar and phytohormone content of the two rootstock-scion combinations. Under drought stress, sorbitol, sucrose and ABA content in root increased compared with the control. So, the differences in the root system and physiological characteristics of the two rootstock-scion combinations under drought stress suggested that the root system of the two rootstock-scion combinations had different water absorption and utilization under drought stress, and the dwarfing rootstock-scion combination Changfu 2/ M9-T337 had better drought tolerance. |
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