Effect of leaf rust (Puccinia recondita) F. spp. Tritici on yield depression in bread wheat Triticum aestivum L.

Nine bread wheat varieties grown throughout in Pakistan were tested for their yield losses due to leaf rust and response to leaf rust caused by Puccinia recondita f. sp. tritici. Wheat varieties Abadgar, Moroco, Inqlab-91, MH-97, Sarsabz, Salman-97, Zardana, Saryab-92 and NR-58 grown in RCBD at Nuclear Institute of Agriculture, Tandojam. Plants were inoculated with spores suspension of uredospores (mixture of local existing virulence) of Puccinia recondita fsp. tritici. The resistance to Puccinla recondita fsp. tritici was evident on all the leaves of Inqlab-91, Salman-97, Abadgar and NR-58, till 10 days after inoculation, but Moroco, Sarsabz, MH-97 and Zardana did not show' any type of Immesistanee against Puccinia recondita f. sp. tritici. The disease severity and average co-efficient of infection of leaf rust differed among the varieties Salman- 97 and Inqlab-91 were immune followed by Abadgar and NR-58 with the severity value of (0) respectively. Whereas Moroco showed the fast rate of disease development followed by Sarsabz, MH-97, Saryab-92 and Zardana with the severity values of (100S, 10S, 5MSS) respectively. NR-58, Sarsabz and Zardana significantly increased plant height in resistant varieties Salman-97 followed, but it was decreased in Moroco, followed by MH-97, Inqilab 91 Abadgar and Saryab- 92. The earhead formation was earlier in MH-97 followed by Sarsabz, Saryab-92, Abadgar and Moroco, but it was delayed in NR-58 followed by Zardana, Salman- 97 and Inqilab-91. Spike length was significantly increased in Salman-97, followed by Inqilab-91, Saryab-92, Abadgar and NR-58 but it was restarted in Moroco followed by Sarsabz, MH-97 and Zardana. The highest number of spikelets/spike was obtained from Salman-97, followed by Ingilab-91, Abadgar, Saryab-92 and NR-58, but-the lowest number of spikelets/spike were obtained from Moroco followed by Sarsabz, MH-97 and Zardana. Fvie maximum number of grains/spike were obtained from Salunan-97, followed by Inqilab-91, Saryab- 92 and Abadgar, but Highly leaf rust susceptible wheat variety Moroco showed poor performance followed by Sarsabz, MH-97, and Zardana. The 1000-grain weight (gm) was significantly increased in resistant varieties Salman-97, followed by Inqilab-91, Saryab-92 and Abadgar, but the Moroco gave lower 1000-grain weight followed by Sarsabz, MH-97 and Zardana. The net grain yield kg/hectare was significantly increased in resistant varieties Salman-97, followed by Inqilab- 91. Sarsabz, MM-97, Zardana and NR-58 decreased saryab-92 and Abadgar but it in highly leaf rust susceptible cultivar Moroco followed. The results showed that Inqilab-91 followed by Salman-97, Abadgar and NR-58 still performed well and gave maximum yield as compared to leaf rust susceptible wheat varieties. The yield losses in Moroco, Sarsabz, MH-97 and Zardana caused by Puccinia recondite f. sp. tritici, may be due to change in virulence of leaf rust population conducive weather conditions for disease development or due to poor performance/response of few resistant genes present in the varieties.