تأثير مرض الصدأ الأصفر في بعض الصفات الطيفية لمحوصل القمح تحت الظروف المروية و البعلية

الملخص EN

The spectral reflectance of wheat under two environmental stresses are studied: the first is the yellow rust disease; which representing the biotic stress and the other is irrigation; representing the abiotic stress.

An artificial infection of Puccinia striiformis f.

sp.

tritici has been applied on 23 /3/ 2009 on four wheat varieties: Acsad65, Doma1, Sham10 and Sham6 under irrigated and rainfed conditions.

The results indicated that the disease symptoms appeared after /13/ days from infection.

Either disease or water stress led to increase the red reflectance values, but to decrease the near infrared reflectance (NIR) and normalized differences vegetation index (NDVI) values.

The significant differences in the values of NIR and NDVI between healthy and diseased plants appeared many days before the visible symptoms took place, but the significance in the red reflectance values didn’t appear until the visible symptoms were shown.

Early detection of disease was obserred about one week before the symptoms has appeared using NIR and NDVI.