| Xanthoceras sorbifolia Bunge,also known as Papaya,Wendengge,civil official fruit,belongs to the genus Xanthoceras,which belongs to the family Xanthoceraceae.Its application in industry,food,medicine,greening barren mountains,soil and water conservation has a very far-reaching development prospects.In this paper,Xanthoceras sorbifolia seeds and one-year-old Xanthoceras sorbifolia seedlings were studied,the optimum proportion of different media and container,the effects of salt stress on Xanthoceras sorbifolia growth,the effects of different drought resistance and water saving measures on soil physical properties,the growth and photosynthesis of Xanthoceras sorbifolia seedlings were studied,it provides theoretical guidance for the propagation of Xanthoceras sorbifolia and the extension of drought-resistant afforestation technology.The results of this study are as follows:（1）The combination of container（13 cm×17 cm）and substrate（peat:vermicompost=1:1）is recommended for seedling raising.Now planting is the best transplanting method to improve the survival rate of Xanthoceras sorbifolia.Seed germination and seedling growth of Xanthoceras sorbifolia were significantly affected by different media and container sizes（P<0.05）,the combination of container（13 cm×17 cm）and substrate（peat:earthworm dung=1:1）had the best effect on seed germination and seedling growth of Xanthoceras sorbifolia,the seed germination rate and seedling height,diameter and biomass were 1.82,2.50,1.69 and 5.90 times higher than those of other treatments,respectively.The survival rate and growth rate of Xanthoceras sorbifolia seedlings were significantly higher than those of 2D and 6d（P<0.05）.（2）The growth inhibition of Xanthoceras sorbifolia seedlings increased gradually with the increase of salt stress concentration from 0.2%to 2.0%.The plant height and diameter biomass of Xanthoceras sorbifolia decreased by 8.82%-45.74%,5.63%-30.83%,23.36%-47.95%compared with CK when the salt concentration was in the range of 0.2%-2.0%.The plant height,biomass and diameter of Xanthoceras sorbifolia were all higher than 0.2%salt at 0.4%salt concentration,and all growth indexes of Xanthoceras sorbifolia seedlings were lower than 0.4%salt concentration,the concentration of 1.6%-2.0%salt decreased significantly（P<0.05）.The results showed that Xanthoceras sorbifolia.had salt tolerance.Therefore,the soil salinity of Xanthoceras sorbifolia should not exceed 0.4%.（3）The net photosynthetic rate（Pn）,stomatal conductance（Gs）,transpiration rate（Tr）,intercellular CO2concentration（Ci）and water use efficiency（WUE）of Xanthoceras sorbifolia seedlings were inhibited by increasing salt stress concentration from 0.2%-2.0%.The photosynthetic gas exchange parameters were significantly different between 0.2%-2.0%nacl treatment and CK treatment（P<0.05）.The photosynthetic physiological indexes decreased with the increase of salt concentration,and the concentration of 2.0%salt decreased to the lowest.（4）There were significant differences in Pn,Gs,Tr,Ci,WUE of the lower canopy fruit seedlings under the treatment of water retaining agent compared with that under the treatment of film covering,grass covering,water retaining agent and control（CK）（P<0.05）.Fm,Fv’/Fm and diameter PSⅡwith water-retaining agent were significantly higher than those with control（CK）（P<0.05）,there was no significant difference between Fm,Fv/Fm,Fv’/Fm and PSⅡwith film coating,grass coating and water saving measures（P>0.05）,and each growth value of applying water retaining agent was the largest.The light contract efficiency and water use efficiency were improved obviously by applying water retaining agent to cover the grass.（5）Soil moisture parameters such as total porosity,capillary porosity,non-capillary porosity,capillary water holding capacity,field water holding capacity and soil water content were the largest under the water-retaining agent mulch measure,and were significantly higher than those of CK（P<0.05）;Compared with CK,soil bulk density was significantly decreased by applying water-retaining agent（P<0.05）.Applying water-retaining agent to cover grass can improve soil water retention and soil physical properties best.（6）All water-saving and drought-resistant measures could increase soil water content and promote the growth of Xanthoceras sorbifolia seedlings.The shoot growth,diameter,biomass and nutrient content of shoot were significantly higher than CK（P<0.05）,which were 71.0%,57.55%,36.50%and 10.87%higher than CK respectively.Application of water-retaining agent and covering grass could promote the absorption of water and nutrients,and promote the growth and biomass accumulation of Xanthoceras sorbifolia seedlings.To sum up,the best combination of substrate and container is（13cm×17cm）and substrate（peat:vermicompost=1:1）,and the best transplanting method is to plant on the spot;The soil salt content of Xanthoceras sorbifolia should be less than 0.4%.Applying water-retaining agent and covering grass is the best measure to save water and resist drought. |
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