Growth dynamics and adaptability of wheat at changed environments

The experiment was laid out in RCB design using 10 varieties sown during November, 1992 in different ecological zones of NWFP by following uniform cultural practices. A number of morphological and physiological characteristics were measured for the wheat varieties tested at different locations (Peshawar, Swat and D.I.Khan) to assess their growth and yield parameters. Under the growth behaviour at varied environments, the RGRs (Relative Growth Rates) of shoots and roots of tested cultivars showed different patterns. These important growth parameters proved the reliability of Peshawar and Swat as high yielding environments for general adaptability. Different varieties like Pirsabak-85, Koh-i-Noor-83 at Peshawar, Sarhad-82 at Swat and Faisalabad-85 and Pirsabak-85 at D.I.Khan showed linear and curvilinear increases in RGR of roots and shoots, emphasizing general trend of growth dynamics over environments. The stability results showed that variety Chenab-79 not only produced higher mean seed yield across the locations but was considered the stable variety having regression co-efficient (bi) 0.80 and deviation from regression -0.225. This was followed by Pak-81 and Pirsabak-91 with 0.97 and 0.86 bi and deviation from regression 0.121 and 0.0236 respectively. Furthermore, a significant linear trend was found between the varietal yield and environmental mean yield of the above stable varieties. It was further documented that varieties characterized by regression co-efficients (bi) of he order of 1.00 and deviation from regressions near to zero had average stability over all environments while those having above and below 1 regression co-efficients were regarded as above and below average stability. On the basis of this model, Pirsabad-91, Pak-81 and Chenab-79 proved to be the average stable cultivars. Koh-i-noor-83 was misfit for both the environments i.e above and below average stable environments. It is probable that these unstable varieties were very sensitive to changes in the environment when small changes produced large changes in yield. These varieties yielded little in some locations but as the environments improved, thus higher yields were observed.