| Pecan(Carya illinoinensis) is one of the famous nuts trees in the world, which also has ecological and economic values. It can produce high grade nuts and can be used as landscaping tree and high grade timber. At present, the commercial production of this specie on a large scale has not formed in China. Propagation technique is one of the key techniques that restrict its industrial development. As pecan has strong deep root characteristic, the development of lateral roots is not easy. When using traditional field nursery method, seedlings are called bare roots seedlings, which have few lateral roots, and the survival rate of transplanting is low. Meanwhile, this kind of seedling is unfit for long distance transport. The traditional pecan nursery of may lengthen its period of seedlings cultivation and downgrade the quality of seedlings, which may limit its extension. In order to solve the problems above, we evaluated the effect of root controlling technique on rootstock quality by three kinds of root controlling technique to cultivate pecan rootstocks. Different container size and substance formula were used, and appropriate combination were select.Research was carried out at the Pecan test base of Meitao Fruit Agriculture Cooperation during 2013-2015, and seeds of Pecan variety “Eliot†which wasis fit for dwarfing rootstock cultivation were chosen for cultivating annual seedling. The main results were as follows:1. Selection of growth regulator and its concentration:Seedling roots in different root-cutting treatment(exsected a certain length of root tip)were respectively soaked, irrigated with different kinds of growth regulator in different concentration.Results showed that,combined with rootcutting treatment,100mg/L-150mg/L GGR and IBA improved shoot growth and roots quality of seedlings by different degree. 150mg/L GGR had best effect of improving the shoot growth. 200mg/L IBA had best effect of improving the roots quality. Irrigating with 10mg/L GGR in early stage had best effect of improving the seedling quality.Control the remaining length of taproot to 2-3cm is the optimal root-cutting treatment.2. The root controlling effect of multiple treatment combined with container were compared: Results showed that, 120g/L-180g/L CuCO3 preparation may inhibit the growth of seedling,especially 180g/L CuCO3 may significantly inhibit its growth. 60g/L CuCO3 and ZnCO3 had no significant effect on seedling growth. 120g/L-180g/L ZnCO3 combined with growth regulator and aerial root controlling technique could significantly improve seedling growth and quality.Seedlings cultivated by comprehensive technique of root controlling container and growth regulator have better quality than that with chemical root controlling technique.3. Selection of container size and substance formula: Compare to seedlings cultivated in five sizes of non-woven bag and bare root seedlings, results indicated that seedlings cultivated in nonwoven bag with a size of 20cm×25cm have optimal rate in all growth performances. However, 20cm×15cm non-woven bag is optimal when considering the cost. In order to select the optimal formula, we designed {4,2} Monotypic center of gravity mixture experiment which included ten kinds of substance formula, and established regression equation. The result showed that peat soil vermiculite : perlite : garden soil = 0.4006:0.1029: 0.2462:0.2503(volume ratio) is the optimal formula. |
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