Tissue Culture And Micrografting Of’Jinboxiang’ Walnut(Juglans Regia L.)

Using stem segment as explants, tissue culture and ex vitro grafting systems were constructed.(1) The best initial culture time is in May and June, explants collected during this time, the viability is higher, more sensitive to exogenous hormone, and more differentiation.(2) The optimum medium for initial culture is MS medium containing1.0mg·L-16-BA,0.3mg·L-1IBA and30g·L-1Sucrose.(3) Subculture in DKW medium containing1.0mg·L-16-BA,0.01mg·L-1IBA got the highest multiplication and growth coefficient.(4) The best rooting system is1/2MS medium (halved macro elements and ammonium nitrate) containing2.0mg·L-1IBA, and lights culture after initial7days darkness treatment. Rooting rate could be up to65.56%.(5) Experiments on stems rooting were conducted after cultured in1/2MS medium containing10mg·L-1IBA with darkness treatment for6days. And the rooting rate could be up to86.7%.(6) the plantlets were harden one week in closed culture bottle and following week in opened bottle under light had higher survival rate which was up to70%.(7) the plantlets were grown in complex substrate containing perlite and vermiculite had optimum effect, which the survival rate was72%after transplantation.(8) The most appropriate treatment of walnut seeds used for rootstocks is stratification by sand, the germination rate could be up to80%, and with orderly emergence of seedling.(9)5-7days after walnut seeds germination, just before true leaf expanding, grafting at this time, highest survival rate was obtained, which reached77.5%.(10) The survival rate of walnut grafted could up to82.5%, when grafting was after harden-off for one week under scattering sunlight.(11) When grafts interface were covered by willow bark, the survival rate of walnut grafted could up to86.7%.(12) Retain the Walnut seeds and intact roots could improve the survival rate of walnut grafted survival rate to be72.7%.(13)When cleft graft on stocks, the length of joints between1.5～2.0cm were the best, and the survival rate was71.1%.(14) The scion with4leaves had higher graft survival rate, which is up to76%.