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Abstract
The present study was conducted in Tissue Culture Laboratory of Agric. Bot. Department, Fac. Agric., Ain Shams Univ., during the period from March 2005 to May 2007 to study the effect of jasmonic acid (JA) at 10-6, 10-5, 10-4 M and Boron (B) at 9.1 and 12.4 mg/l as well as their combinations on in vitro tuberization of two potato cultivars; Spunta and Diamont. Single node cuttings were used for microtuber production using MS medium supplemented with 0.7 % agar, 80 g/l sucrose and kinetin at 2 mg/l and were incubated in dark at 15° C. Control medium was free from JA and contained the basic concentration of B (6.2 mg/l boric acid) in Murashige and Skoog (MS) medium. additional B to the medium greatly affected microtubers induction and growth. Boron showed an increase in microtubers number, fresh and dry weights, percentage of microtuberized explants and microtubers size. These effects were directly proportion to the concentration of boron. Adversely, JA showed significant reduction in the previously mentioned parameters at 10-6, 10-5 M while at 10-4 M concentration, they were resulted in completely. Suppression boron treatment showed an increase in total soluble carbohydrates and plant growth promoters IAA, GA3 and zeatin concentrations and reduced ABA in the resultant microtubers. The opposite trend was true with JA treatments. The positive effects of B application in the tissue culture medium were extended to the resultant minitubers in the greenhouse. The presence of B with JA at 10-6 and 10-5 M in the medium reduced the inhibition effect of JA on the developed microtubers especially when the low concentration of JA (10-6 M) was accompanied with the high concentration of B (12.4 mg/l). The effects of B and JA on microtubers induction and development as well as the correlation changes in total soluble carbohydrates and endogenous phytohormones were determined and discussed. In relation to microtuber vigority and subsequent minituber production.