EFFECT OF NACL SALINITY ON GROWTH AND DEVELOPMENT OF JOJOBA CLONES .2. NODAL SEGMENTS GROWN-INVITRO

In an effort to determine the degree of correlation between effects of salinity in vitro and in vivo, the response of nodal segments of jojoba (Simmondsia chinensis) was studied in four superior clones under salinities of 0 - 274 mM NaCl and in a mixed group of clones under 171 mM NaCl. In general, NaCl up to 137 mM did not markedly inhibit rate of shoot elongation, biomass and node production in superior clones 106, 104, and 154, but higher levels distinctly inhibited growth. Growth of clone 64, one of the superior clones, showed inhibition at all salinity levels. Clone 154 was the most tolerant of the four up to 205 mM NaCl. Sodium accumulation was highest in shoots of clone 64 and lowest in clone 154. Potassium content decreased progressively with salinity in all but clone 154, in which no change in potassium content occurred. The response of other clones of the mixed group to 171 mM NaCl was highly variable, some exhibiting 70-80% inhibition in shoot elongation as compared with the control, and others remaining largely unaffected even when sodium accumulated to high levels. When these results were compared with findings of the preceding ex vitro study, it was found that in spite of anatomical and physiological differences, the response to salinity of nodal segments in vitro and that of the whole plant in vivo was similar, supporting the idea that in vitro screening of organs offers an efficient, inexpensive method of preselecting for salt tolerance.