Effect of leaf rust disease on photosynthetic rate, chlorophyll contents and grain yield of wheat

The objective of the present study was to investigate what extent the leaf rust disease severity affects the photosynthesis and grain yield in wheat. This was done by estimating disease severity, photosynthetic rate, chlorophyll contents and grain yield loss in six wheat varieties under the natural and fungicide treated conditions. Among six wheat varieties/lines (Galaxy-13, Millat-11, Lasani-08, Faisalabad-08 and two wheat lines NW-1-8183-8 and NW-3-3341-7), the mean severity level of leaf rust was the highest on Galaxy-13 and Faisalabad-08, however, grain yields were also higher in Galaxy-13, Millat-11 and FSD-08. Wheat lines NW-1-8183-8, NW-3-3341-7 and wheat variety Millat-11 showed less severity with high yield. One application of fungicide, propiconazole reduced the rust infections significantly and enhance the photosynthetic rate and chlorophyll contents, resulting in significantly higher yield in fungicide treated plots. On the basis of leaf rust severity and grain yield assessment, wheat varieties Galaxy-13 and FSD-08 were found highly tolerant against rust diseases. Maximum cost-benefit ratio was found in NW-3-3341-7 (1:12.2) when treated against rust fungicide. The study concluded that rust disease significantly reduced the grain yield when not protected by fungicide. Integration of host resistance with minimum fungicide application can reduce the deleterious effect of leaf rust and gives maximum net returns.