EFFECT OF FOLIAR SPRAYING OF SOME CHELATED MICROELEMENTS ON GROWTH, YIELD AND CHOCOLATE SPOT DISEASE SEVERITY OF FABA BEAN

ABSTERACT: Field experiment using three faba bean cultivars namely Sakha 1, Sakha 4 and Giza 716 was carried out to study the efficacy of foliar spraying chelated Fe, Mn and Zn individually on vegetative growth, yield and its components, some biochemical constituents and its relation to chocolate spot disease severity caused by Botrytis fabae Sard. during two successive seasons 2017/2018 and 2018/2019 at Etay El-Baroud Agricultural Research Station Farm, El-Beheira Governorate. Sakha 1 cv. had the highest shoot dry weight and leaf area/plant in both seasons. Sakha 4 cv. was the earliest flowering and maturity in the first and second seasons, respectively. Sakha 4 cultivar had the tallest plant and the heaviest 100-seed weight in both seasons, but Giza 716 had the highest number of pods/plant, seed yield /plant and seed yield/fed. in the first season, however Sakha 4 cv. was surpassed the other cultivars in the second season. Chelated Fe, Mn and Zn foliar spray had excellent effects in increasing faba bean growth and yield compared to the fungicide Mancozeb and control treatments. Zn treatment significant increased mean values of shoot dry weight, leaf area/plant, number of branches/plant and seed yield/plant in both seasons. Also, it had the first grade in case of the plant height and seed yield/fed. in the first season, only. Fe treatment significantly increased number of pods/plant and 100-seed weight in the first season, and seed yield/fed. in the second season. Giza 716 cv. had the highest content of chlorophyll a, chlorophyll b and chlorophyll a+b in both seasons. Sakha 4 cv. had the highest percentage of the seed carbohydrates and protein contents. In case of peroxidase and polyphenol oxidase activities, Giza 716 cv. had the first grade. Fe significantly increased chlorophyll a in the first season and chlorophyll b and chlorophyll a + b in both seasons. Zn treatment significantly increased seeds total carbohydrates%, total protein %, leaves peroxidase and polyphenol oxidase activities. Sakha 1 cv. had the least chocolate spot disease severity in the first season and Giza 716 in the second season. The three tested faba bean cultivars sprayed with Mancozeb reduced disease severity in both seasons followed by Fe in the first season and Zn in the second one. Data clear that there were negative association between disease severity and peroxidase and polyphenol oxidase activities in all cases. So it could be concluded that the used micronutrients could resist the detrimental effects of Botrytis fabae on the plant growth and improve yield production.