Selection Of Superior Cultivars, Photosynthetic Characteristics And Water Physiology Of Prunus Armeniaca×sibirica In Loess Hilly Area Of North Shaanxi

The Loess Hilly Area of North Shaanxi is one of important production base of apricot, Prunus armeniaca×sibirica in China. Longwangmao, main cultivars in North Shaanxi, has lower economic benefit because it is early abloom, poorer freezing resistance and it is planted in atrocious habitat. So it is starved that better variety of freezing resistance should be introduced into the area, scientific planting and rational water management should be actualized. In this paper, we introduced 4 cultivars,Longwangmao,Yiwofeng,Baiyubian,Youyi from Hebei province in 1996, and meanwhile, we compared growth, phonological phase, yield, apricot quality, freezing resistance and photosynthetic characteristics of 4 cultivars. At the same time, we studied the growth rule and water characteristic of Longwangmao. The main results showed as follows:(1) According to synthetically analysis and comparsion of growth, phonological phase, yield, apricot quality and freezing resistance, the Youyi was the best and adapted to be extended in the Loess Hilly Area of North Shaanxi, next is Yiwofeng.(2) In the Loess Hilly Area of north Shaanxi, the phonological phase of apricot trees on sunny or semi sunny slope was earlier 5-7 days than that of shady or semi shady slope, and more easily damaged by late frost. So the trees should be planted on shady or semi shady slope. The result of comparing light curve of Longwangmao, Yiwofeng, Youyi showed that light saturation point was 600,600 and 400μmol/(m~2·s)respectively, most lower than that of Amygdalus communis L (1 714μmol/(m~2·s))and Prunus persica(1 479μmol/(m~2·s)). This may be one of reason that the trees on shady or semi shady slope grow and beard better than that on sunny or semi sunny slope.(3) The diurnal variation of stomatal conductance(Gs) of Longwangmao, Yiwofeng and Youyi were similar to their diurnal variation of photosynthetic rate(Pn), which showed that Pn variation was mainly affected by stomatal factor. Among the 3 species, Longwangmao and Yiwofeng had higher Pn and transpiration rate (Tr)than those of Youyi. So Youyi was suitable to be grown in more light and soil moisture condition.(4) In the Sand-covered loessal soil and Yellow cinnamon soil, leaf water potential, relative water content(RWC), water saturated deficit and tissue density of Longwangmao was significantly affected by soil moisture. The Prnuus armeniac×sibirica had stronger drought resistance. With decline of soil moisture, the leaf water-holding ability of Prnuus armeniac×sibirica in Yellow cinnamon soil was bigger degree of declining than that of in Sand-covered loessal soil, This showed that the tree had stronger drought resistance in Yellow cinnamon soil than that of in Sand-covered loessal soil.(5) The results of water consumption and water use efficiency of Longwangmao showed that the Prnuus armeniac×sibirica had remarkably over evaporation phenomena under enough soil moisture, but under moderation aridity of soil moisture, the water use efficiency of Prnuus armeniac×sibirica could be remarkably improved.(6) The stem diameter, side-shoot length, dry weight of shoot, dry weight of root and biomass of Longwangmao declined with the declining of soil moisture. The growth of Longwangmao in Yellow cinnamon soil was remarkably higher than that of in Sand-covered loessal soil. It was need above 52% f_θof soil moisture to get bigger biomass.