Changeability in Stripe Rust Infection and Grain Yield of Wheat Associated to Climatic Conditions

STRIPE rust infection caused by Pucciniastrii formis f. sp. tritici was investigated in ten Egyptian wheat cultivars under field conditions during two seasons (2016/17 and 2017/18) at two locations (Sakha and Sids) differ climatologically in Egypt. Variable levels of rust infection followed by a significant reduction in grain weight were recorded at both locations. Stripe rust infections for Sids location (20S - 90S) were higher than those of Sakha location (TrMS - 70S). Average coefficient of infection (ACI) and grain weight loss for Sids location, reaching 90 ACI (Gemmeiza-11) and 23.12% (Giza-160), were higher than those of Sakha location up to 70 ACI and 16.72% in Giza-160. Grain weight loss was strongly associated with ACI among cultivars for both locations, recording r=0.9044 for Sakha location and r=0.8866 for Sids location. Climatic variations were recorded at both locations during the first four months of 2017 and 2018. Rainfall and relative humidity for Sakha location were higher than those of Sids location while wind speed for Sids location was higher than that of Sakha location. Temperatures were relatively close at both locations. ACI values for Sids location were higher than those of Sakha location, revealing correlation with climatic factors. This suggests that wind speed may play an important role in dispersal while relatively heavy rainfall may have opposing effects. The temperature was the main limiting factor for stripe rust infection (negatively associated), followed by relative humidity (positively associated). Our discovery represents a powerful tool for predicting disease infection and management.