Micropropagation Of Almond's Rootstocks

The micropropagation procedures of two kinds of Almond's rootstocksansen and Nemaguard had been researched, including the establishment of aseptic cultures, shoot proliferation, selection of suitable medium and hormone, rooting and acclimatization. A feasible and practicable micropropagation system of these two rootstocks had been made. High survival rate of the explants can be achieved when the explants were collected in the end of March. Washing the explants under running tap water to remove some of the dirt and contaminations, and in 0.1% Hgcl2 for 8mm (for Hansen) and I 0mm (for Nemaguard), rinsed 3~?4 times with sterile water . The stems, with single bud, were cultured on Murashige and skoog (1962) medium (MS) added with I .Omg/L N6-benzyladenine (BA) and 0.2mg/L gibberellic acid (GA3). The survival rate were 87.5% (for Hansen) and 82% (for Nemaguard). During the shoot proliferation, we found that MS basal medium was more suitable for growth and subculture of the shoots than MS-RN G~ and OS basal mediums. The exogenous application of cytokinins were very necessary for shoots proliferation, the multiple effect of BA was better than kinetin (KT). In a suitable range, 0--- 1 .Smg/L, the higher concentration of BA was used. the higher proliferation rate was achieved. Combinations of cytokinin and auxin can stimulate the growth of shoots, and the effect of indole-3-acetic acid (IAA) was better than indole-3-butyric acid (IBA) and naphthalane acetic acid (NAA). 0.2mgIL GA3 andlO0mg/[. lactalbumin hydrolysate (LH) improved the proliferation rate and made the shoots growth better. For Hansen, the optimum proliferation medium was MS basal medium supplemented with 1.5mg/L BA. 0.lmgIL IAA, 0.2mgIL GA3 and IOOmg/L LH; and MS basal medium supplemented with 2.Smg/L BA, 0.lmg/L IAA, 0.2mg/L GA3 and IOOmg/L LH was also found to be favorable for Nemaguard's proliferation, It was good to keep the cultures at 25扖 ~梸28 ~C on a I 0----] 2hr.photoperiod with a light intensity of 2,000lx on the cultures, and to subculture Hansen's cultures every 3odays, Nemaguard's cultures every 40 days. The proliferation rate were 5.02 and 4.25. MS basal medium added 0.5mg/L GA3, 0.lmgIL IAA and O.lmg/L IBA made the shoots elongation and better growth. One-half MS basal medium was more favorable on root formation than MS medium. The 3 rooting rate was increased significantly when we added auxin in the medium. It was good to use 0.5mgIL IBA to induce root, the higher rooting rate (62.5%) and better roots were obtained. Dark treatment in the root initiation phase stimulated to root, the rooting rate were over 85%, and 0.1% activated charcoal (AC) improved to root. Soaking of the base of the shoots in lOOmg/LIBA solution for 15mm, then transplanting into I/2MS medium without hormones obtained over 95% rooting rate. Ex-vitro rooting treatment had not gotten successful results. Three-steps acclimatization procedure was used to acclimatize the plantlets successfully to free Iivin~ condition. The survival rate were over 70%.