EFFECTS OF MOISTURE STRESS ON LEAF APPEARANCE, TILLERING AND OTHER ASPECTS OF DEVELOPMENT IN TRITICUM-TAUSCHII

A glasshouse study was conducted to describe the dynamics of leaf and tiller appearance of four accessions of T. tauschii (Tt 04, Tt 17, Tt 65 and Tt 74) and to determine the influence of moisture stress (treat ments were high and low moisture, imposed seven days after transplanti ng) on these and other aspects of development in this wild wheat. Unde r high moisture conditions, accessions differed greatly in flag leaf d imensions, culm length and seed number per spike, the values being low er in Tt 04 than in the other accessions. Low moisture strongly reduce d values for these traits, with Tt 04 being least affected, but overal l, there was no apparent association between the values obtained for t hese variables in the high moisture conditions and the effects of mois ture stress. For three of the four accessions, final leaf number on th e main culm was significantly lower in the low moisture treatment than in the respective control (P < 0.05), but the differences between tre atments (ca. 0.5 leaves or less) were very small. Maximum tiller numbe r, on the other hand, was strongly reduced by low moisture, and initia tion of tillering was inhibited until water was reapplied. There were no apparent after-effects of the moisture regime on the rate of subseq uent tiller appearance. The four accessions differed in their leaf app earance rates, giving phyllochron values (117-142 degrees Cd leaf(-1)) within the range reported for hexaploid wheat. Low moisture tended to increase phyllochron, but in only one accession was this effect signi ficant. Thus, depending on the accession, low moisture did not affect, or slightly decreased (by ca. 15-20%) the rate of leaf appearance. Th ese effects were similar to those reported for cultivated wheat sugges ting that there would be little scope for using these accessions of T. tauschii in breeding for stress tolerance.