| As the largest apple growing area in China,the Loess Plateau is often threatened by drought,water shortage and soil nutrient deficiency,which seriously limits the development of apple industry in this area.Malus prunifolia,an apple rootstock,is a unique apple rootstock resource in this area.It has strong comprehensive resistance.At present,the way of seedling propagation is mainly used in production,but there are few provenances.M.prunifolia seed is a hybrid,with large variation in seedling propagation and irregular orchard trees.Taking the seedling propagation as the control,the evaluation of the comprehensive resistance of asexual propagation seedlings is of great significance for the effective utilization of this resource and promoting industrial development.Different grafting height and planting height of apple rootstock have important effects on plant growth and stress resistance.Therefore,by comparing the growth,flowering and branching of apple plants under different rootstock planting heights and the drought resistance of plants under different grafting heights,this paper explores the impact of rootstock grafting height on drought resistance and the impact of rootstock planting height on growth and development,so as to provide a theoretical basis for the research of apple planting technology in the future.In this experiment,potted 1-year-old seedlings and tissue culture seedlings of M.prunifolia were grafted with apple’Qincui’,in which M.prunifolia seedlings were grafted at low position(10cm from the ground)and M.prunifolia tissue culture seedlings were grafted at low position(10cm from the ground)and high position(60cm from the ground).Three kinds of seedlings were treated with long-term drought,and the effects of asexual reproduction and grafting height on drought resistance of M.prunifolia were studied.In addition,the seedlings of M.prunifolia and M.prunifolia tissue culture seedlings sown in the same year were used as experimental materials for hydroponic low nutritional stress treatment,and the effect of asexual reproduction of M.prunifolia on low nutritional stress resistance was studied.Apple plants grafted on M.prunifolia,M26 and M26/M.prunifolia rootstock under three planting heights of full burial(≤0cm),half burial(5-10cm)and full exposure(≥15cm)were used as experimental materials to compare the effects of rootstock planting height on plant growth,branching and flowering.The main results are as follows:1.After long-term drought stress,the changes of plant biomass,root index,net photosynthetic rate(P_n),transpiration rate(T_r),instantaneous water use efficiency(WUEi),total chlorophyll content and antioxidant enzyme(SOD,POD)activity in leaves of M.prunifolia seedlings were not significantly different from those of M.prunifolia tissue culture seedlings.The leaf relative water content(RWC),free proline content,leaf relative conductivity and malondialdehyde(MDA)content of M.prunifolia tissue culture seedlings were significantly different from those of seedlings.Using the above indexes to calculate the membership function,the results are:tissue culture seedlings 0.5113,seedling 0.5393,the difference is not significant.The result showed that under long-term drought stress,there was no significant difference in drought resistance between tissue culture seedlings and seedlings of M.prunifolia.2.After long-term drought stress,the changes of root index,RWC,P_n,T_r,WUEi,total chlorophyll content and antioxidant enzyme(SOD,POD)activity of M.prunifolia high grafted seedlings were less than those of low grafted seedlings.The changes of plant biomass,free proline content,leaf relative conductivity and MDA content in leaves of M.prunifolia high grafted seedlings were significantly less than those of low grafted seedlings.Using the above indexes to calculate the membership function,the results are:high grafted seedlings 0.5628,low grafted seedlings 0.5113,the difference is significant.The results showed that high grafting(60cm from the ground)could improve the drought resistance of M.prunifolia.3.Under low nutritional stress,the changes of biomass,root index,P_n,photosynthetic pigment content,antioxidant enzyme(SOD,POD)activity,endogenous plant hormone zeatin nucleoside(Z+Zr),IAA and ABA content of M.prunifolia seedlings were not significantly different from those of M.prunifolia tissue culture seedlings.The changes of leaf relative conductivity,MDA content and free proline content of M.prunifolia tissue culture seedlings were significantly different from those of seedlings.Using the above indexes to calculate the membership function,the results are:tissue culture seedlings 0.5281,seedling 0.5526,the difference is not significant.The result showed that there was no significant difference in low nutritional stress resistance between tissue culture seedlings and seedlings of M.prunifolia.4.The plant height growth and dry perimeter growth of M.prunifolia decreased with the increase of rootstock planting height,the number of total branches and the proportion of medium and short branches increased with the increase of rootstock planting height,the content of P_nand total chlorophyll in leaves decreased with the increase of rootstock planting height,and the average number of flowers increased with the increase of rootstock planting height;The plant height growth,dry week growth and total branch number of dwarf intermediate rootstock M26/M.prunifolia decreased with the increase of rootstock planting height,the proportion of medium and short branches increased with the increase of rootstock planting height,the content of P_nand total chlorophyll in leaves decreased significantly with the increase of rootstock planting height,and the average number of flowers decreased with the increase of rootstock planting height,of which 2 plants with total leakage(≥15cm)did not flower;The plant height growth,dry week growth and total branch number of dwarf rootstock M26 decreased with the increase of rootstock planting height,the proportion of medium and short branches increased with the increase of rootstock planting height,the content of P_nand total chlorophyll in leaves decreased significantly with the increase of rootstock planting height,and the average number of flowers decreased with the increase of rootstock planting height,among which one plant with total leakage(≥15cm)did not flower.Based on the above indicators,the results show that for Malus prunifolia,the rootstock is most suitable when the planting height is more than 15cm.The plant growth is low,the tree body is dwarf,which is convenient for management.At the same time,there are many total branches and flowers,and the proportion of medium and short branches is high,which is conducive to the fruit.For dwarf intermediate rootstock M26/Malus prunifolia and dwarf rootstock M26,when the rootstock planting height is≤0cm,it is not conducive to the fruit.When the rootstock planting height is more than 15cm,it inhibits the plant growth.The rootstock planting height is the most appropriate when it is 5-10cm,which can effectively control the tree height,dwarf the plant and ensure the growth of the tree body.At the same time,the number of flowers and the proportion of medium and short branches are high,which is conducive to the fruit. |
PDF Full Text Request