Abstract
The stripe rust is the most striking among various factors that contribute towards enormous wheat yield losses in the northern Punjab and NWFP. Investigations revealed that there exists a direct linkage between the disease level of Puccinia striiformis Westend f.sp. Tritici Eriksson and weight loss of kernel in the most common wheat varieties sown in Pakistan. The kernel weight was significantly negatively correlated with the proportion of leaf area affected by stripe rust. The correlation coefficient (-0.9185) depicted highly significant effect of stripe rust on lowering 1,000 grain weight, ultimately the wheat yield. Variation in resistance level was also observed among different wheat varieties. The extensively cultivated wheat variety, Inquilab-91 proved to exhibit minimum kernel weight loss followed by Bakhtawar and Wafaq-2001. The Morocco, however, expressed as the most susceptible of all the varieties with maximum grain weight loss. Evaluation of disease resistance revealed that wheat variety Bakhtawar proved to be the moderately susceptible whereas Wafaq-2000, Inquilab-91 and Morocco ranked as susceptible to Puccinia striiformis. Among the four wheat varieties grown to assess the yield loss, sowing of Inquilab-91 and Bakhtawar was recommended because of their potential to withstand heavy yield losses inflicted by the stripe rust.