Effects Of Diferent Planting Depth Of Apple Dwarting Rootstock On Diatribution Of Root System, Hormone Content,fruit Yields And Quality

In the present study, to obtain the optimal planting depth for apple dwarfing interstock,Fuji and Gala apple trees grafted on dwarfing interstock were respectively planted withdifferent planting depth (5,10,15,20and30cm for intersock)in Yangling, Fengxiang,Yongshou and Pucheng, Shaanxi Province,then3-year old trees were used to investigate theeffects of the planting depth on root system distribution, root hormone, fruit yields and quality.The results showed that：1. In dwarfed apple orchard, the fine roots (＜2mm) mainly distributed in the soil layerof0–40cm, and the fine roots were more than80%of total roots. In the treatment of15–20cm planting depth of dwarfed interstock, the sum of fine and total roots were more than that inother treatments. The sum of the fine roots was increased by13.6%–41.5%, and the sum oftotal roots was increased by18.2%–33.3%than other treatments, the weight of the dry rootswas increased by11.2%–68.4%. When the planting depth of dwarfed interstock is15cm, thesum of the fine roots, total roots and the weight of the dry roots was increased by10.1%–51.6%,13.8%–56%, and22.6%–66%respectively, which is in Fengxiang, Yongshouand Pucheng. Dwarfed Gala with15–20cm planting depth of dwarfed interstock, thevariation of roots was consistent with Fuji.2. In July, August, September and October, dwarfed interstock depth of15cm,0-20cm,20-40cm and40-60cm soil layer, the IAA, ZR, GA content were the highest which promotedthe root growth; however, the ABA content which could inhibit root growth of all the threesoil layers was less; while the (IAA+GA3+ZR)/ABA ratio was the highest, which showedthat it was helpful for stimulating the growth of root system, when the dwarfed interstockdepth is15cm.3. In yangling, under the condition of15cm planting depth of dwarfed interstock, theyield of Fuji was higher than other treatments by1.26-1.26kg, the single fruit weight washigher by37.6–60.1g, the soluble solid contents increased by0.6–2.3%, the fruit hardnessincreased by9.7–12.7%. Moreover,15cm treatment showed more competitive advantage, i.e., fruit coloring and the titratable acid. Planting dwarfed interstock in15–20cm couldsignificantly improve the skin color; increase the overall color of the fruit and the degree ofred. In Fengxiang, Yongshou and Pucheng, under the treatment of15cm planting depth ofdwarfed interstock, the fruit qualitiy was better than other treatments, the variation wasconsistent with that which is in Yangling.4The deeper interstocks buried, the higher trees grew. At Yangling, when the interstockdepth of Fuji apple tree was15cm, the crown diameter was259.8cm; the sum of leaderbranches was up to16, and the branch angle was90-100°. At Fengxiang, Yongshou,Pucheng and other places, when the interstock depth was15cm, the crown was middle, andthe tree had more branches. At Yangling, interstock depth of Gala apple tree was15cm; thecrown diameter was254.4cm; the sum of leader branches was up to13, and the branchangle was90-100°. It showed that the variation between Gala and Fuji was consistent.In summary, the treatment of dwarfed interstock depth of15-20cm promoted the fineroot and the root hormone content growing, while inhibited hormone content of fruit. Theresult lead the tree absorbed more nutrients for growth and developed the fruit quality.