Screening Sorghum Accessions for Resistance against Anthracnose and Grain Mold through Inoculating with Pathogens

Abstract

Aims: The aim of this study was to identify resistant accessions against pathogens, causing anthracnose and grain mold. Study Design: Study was laid out in a randomized complete block design with three replications. Data for anthracnose rating, grain mold severity, seed weight, and percent germination rate were analyzed using the command PROC GLM. Place and Duration of Study: The study was carried out at the Texas AgriLife Research Farm, Burleson County, Texas, in 2010, 2014, and 2015 growing seasons. Methodology: Forty-seven accessions were planted in 6 m rows 0.31 m spacing. Plants were inoculated by placing Colletotrichum sublineola colonized grain in the plant whorls 30 days after planting. Disease evaluation was initiated 30 days post-inoculation and thereafter on a weekly basis for three consecutive weeks. Grain mold experiment: Three treatments were used: 1) plants sprayed with A. alternata alone, 2) a mixture of A. alternata, F. thapsinum and C. lunata, 3) control plants sprayed with sterilized water and exposed to natural infection. At 50% bloom, three panicles per line within replication were inoculated for each treatment. Results: Eleven accessions, including PI641874, PI656070, PI656115, and PI534167 were consistently resistant when challenged with the anthracnose pathogen, C. sublineola. Accessions PI534047 and PI574455, exhibited resistance to moderately resistance grain mold response when challenged with the treatments. Seed weight, germination rate, and mycoflora analysis which are factors in determining grain mold resistance also were measured. Across the accessions, mean seed weight ranged from1.4 g to 4.3 g per 100 kernel and germination rate ranged from 26 to 87%.  Conclusion: The resistant accessions identified in this study can be used in breeding programs to develop anthracnose and grain mold resistance lines.