Association studies for agro-physiological and quality traits of triticale x bread wheat derivatives in relation to drought and cold stress.

Correlation coefficient analysis conducted on 22 triticale x bread wheat derivatives along with six checks to select true- breeding derivative(s) for future hybridization programme with tolerance to drought and cold stress conditions as well as better quality traits revealed significant correlation of grain yield with spikelets per spike, biological yield, harvest index, leaf area index. Interestingly, the grain yield and drought susceptibility index showed no association. However, with cold tolerance it showed significant positive correlation indicating the desirability of certain plant traits under cold stress. The grain yield exhibited no association with quality traits which might assist in the predictability of high yielding varieties with high protein, total sugars, reducing sugars and non-reducing sugars. Path coefficient analysis revealed that biological yield had the highest positive direct effect on grain yield followed by harvest index, specific leaf weight, stomatal number, 1000 grain weight, stomatal size, spikelets per spike and days to heading. Therefore, indirect selection for these plant traits in order should be exercised in selecting drought tolerant genotypes. Two genotypes (RL-124-2P2 and RL 111P2) were found to be drought and cold tolerant with high grain yield, spikes per plant, spikelets per spike and leaf area index.

In vitro regeneration of Acacia catechu Willd. from callus and mature nodal explants--an improved method.

Callus was derived from cultured cotyledons on MS medium supplemented with 2,4-D (0.25 mg/l) and NAA (0.25 mg/l). Plantlets were regenerated from the callus and nodal explants on MS medium containing BAP (2.0 mg/l) and Kn (2.0 mg/l), and further multiplied on the same medium. Addition of adenine sulphate (25.0 mg/l), ascorbic acid (20.0 mg/l) and glutamine (150.0 mg/l) in the medium resulted in enhanced axillary branching. Multiple shoots formed after 6 weeks were separated and subcultured in the fresh medium of same composition. For rhizogenesis, microshoots of 2.0-2.5 cm length were dipped in sterilized IAA solution (10 mg/l) for 24 hr followed by transfer to half strength MS medium containing activated charcoal (0.02%) resulting in rooting (75%) within 8 weeks. The rooted plants were transferred to pots containing sterilized soil and sand mixture for hardening and 71% survival was recorded. Fifty true to type plantlets of A. catechu could be obtained within seven months of culture establishment.