Effect of some phytohormones on the growth of Alternaria solani and their possible role as resistance factors in tomatoes

Abstract

Plants resistance against early blight were obtained by Alternaria solani was examined using leaf disks from 7 cultivars of tomato (Lycopersicon esculentum mill) plants .Disks(1.5 mm diameter) were obtained from leaves of the same age per cultivar (30-80 days) postemergence. The leaf disks were spray- inoculated with a conidial suspension of A. solani, floated on solutions containing either 1-naphthaleneacetic acid(NAA), Indolacetic acid (IAA),6-benzylaminopurine(BAP),abscisic acid(ABA) or H2O. Treated leaf disks were incubated at 25ﹾC in the dark for 5 days. Determination of susceptibility was obtained and rating of leaf disks was recorded and compared with leaf ratings field trials. The significant range of reduction rating was found in NAA application (5.6-1.8),(6.3 – 2.0) and (6.8-1.7) for example after 30,60 and 80 days postemergence, and there was a significant data in vitro assay when leaf disks were taken from very late postemergence . Also it was found that Ace followed by super marmmand and super queen, respectively showed high positive response to these applications. Maximum resistance of early blight showed among different cultivars was obtained when ABA was applied.