| Pinus koraiensis is the main afforestation tree species in Northeast China,and it is also an important precious timber tree species in China.Because Korean pine grafted seedlings are the main source of afforestation seedlings of Korean pine economic forest,it is particularly important to select reasonable cultivation measures to promote the growth of Korean pine grafted seedlings and early flowering and fruiting of scions.Studies have shown that suitable rootstocks of the same genus can promote the flowering of scions.Fertilization in autumn can alleviate the ’ nutrient dilution ’ of grafted seedlings during the lignification period and ensure the normal growth of scions in the next growing season.Rootstock pruning can solve the ’ rootstock substitution ’ phenomenon of Korean pine grafted seedlings.Fertilization in the growing season can ensure the physiological function and productivity of scions.However,the interaction between autumn fertilization and rootstock type on the growth,physiology and flowering of Korean pine grafted seedlings has not been reported,and the effects of rootstock pruning intensity and nitrogen application rate in growing season on the growth and physiology of Korean pine grafted seedlings with different rootstock types after autumn fertilization are still unclear.In this study,P.sylvestris,P.koraiensis and P.armandii grafted seedlings were used as materials to explore the effects of nitrogen application rate and rootstock type on the growth,physiology and flowering of Korean pine grafted seedlings in autumn.Effects of rootstock pruning intensity and nitrogen application rate in growing season on growth and physiology of Korean pine grafted seedlings under different nitrogen application treatments in autumn.Further improve the cultivation system of Korean pine grafted seedlings,and provide technical reference and theoretical support for determining the suitable rootstock type,nitrogen application level and rootstock pruning strength of Korean pine grafted seedlings.The main results are as follows :(1)Nitrogen application in autumn can significantly promote the growth of three rootstock types of Korean pine grafted seedlings in the next growing season.The rootstock type was Korean pine,and the nitrogen application rate in autumn was 1.0 g / plant.The height growth and basal diameter growth of Korean pine grafted seedlings were the largest in the next growing season.The rootstock types were P.sylvestris and Korean pine,and the scion growth increased first and then decreased with the increase of nitrogen application rate.The rootstock type was P.armandii,and the scion growth increased with the increase of nitrogen application rate.(2)Nitrogen application in autumn can significantly promote the physiological indexes of grafted seedlings of three rootstock types at the end of growing season.The rootstock type was Korean pine,and the nitrogen application rate in autumn was 1.0 g / plant.The nitrogen concentration,chlorophyll content and soluble protein content of Korean pine grafted seedlings were the highest at the end of the growing season.The rootstock types were P.sylvestris and Korean pine,which increased first and then decreased with the increase of nitrogen application rate.The rootstock type was P.armandii,which increased with the increase of nitrogen application rate.(3)Rootstock type and nitrogen application rate in autumn had significant effects on flowering plant rate and total number of flowers in the next growing season.The rootstock type was P.sylvestris,and the nitrogen application rate in autumn was 1.0 g / plant.The flowering plant rate and total flowering number of Korean pine grafted seedlings in the next growing season were the largest.The rootstock type is that the scion of P.armandii does not bloom in the next growing season;the scions of P.sylvestris and Korean pine only had male flowers in the next growing season.With the increase of nitrogen application rate,the flowering plant rate and the total number of flowers increased first and then decreased.(4)Nitrogen fertilizer application in growing season can significantly promote the scion growth and the increase of chlorophyll content and nitrogen concentration of scion needles of P.sylvestris and Korean pine.Regardless of the pruning intensity,with the increase of nitrogen application in the growing season,the scion growth,chlorophyll content and nitrogen concentration of the grafted seedlings of Korean pine showed an increasing trend.When the pruning intensity of the rootstock was 40 % and the nitrogen application in the growing season was 18 g / plant,the maximum.(5)Under different pruning intensities,the effects of nitrogen application rate in growing season on NSC content of scion needles of P.sylvestris and Korean pine were different.Under no pruning and 40 % pruning intensity,the NSC content of scion needles decreased first and then increased with the increase of nitrogen application rate in growing season.Under 70 %pruning intensity,the NSC content of scion needles increased first and then decreased with the increase of nitrogen application rate.The NSC content of scion needles was the highest when the rootstock pruning intensity was 40 % and the nitrogen application rate in the growing season was 18 g / plant.(6)Under the same rootstock pruning intensity and nitrogen application rate in growing season,the growth and physiological response of Korean pine grafted seedlings treated with autumn nitrogen application were better than those of Korean pine grafted seedlings without autumn nitrogen application.In summary,nitrogen application in autumn can improve the physiological level of the scion at the end of the growing season and promote the growth of the scion in the growing season of the three rootstock types of Korean pine grafted seedlings.The rootstock type is Korean pine,and the nitrogen application rate in autumn is 1.0 g / plant.The application of nitrogen fertilizer in autumn promoted the flowering of the scions of P.sylvestris and Korean pine in the next growing season.The rootstock type was P.sylvestris and the nitrogen application rate in autumn was 1.0 g / plant.Rootstock pruning and nitrogen application in the growing season could significantly affect the scion growth,chlorophyll content,nitrogen concentration and non-structural carbohydrate content of grafted seedlings of Korean pine.The best performance was achieved when the rootstock type was Korean pine,the rootstock pruning intensity was 40 %,and the nitrogen application rate was 18 g / plant.Under the same pruning intensity and nitrogen application rate in growing season,the performance of seedlings treated with nitrogen application in autumn was better than that of seedlings without nitrogen application in autumn.The rootstock type is Korean pine,nitrogen application in autumn is 1.0g / plant,40 % rootstock pruning intensity,and nitrogen application in growing season is 18 g /plant,which is most conducive to promoting the growth of Korean pine grafted seedlings and improving physiological indicators. |
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