Abstract
Two field experiments were conducted at AL-Rashidia Location, west north Mosul city , Nineveh province, during two successive growing of 2008 : spring and autumn, in a sandy Loam soil to study the response growth , yield and quality of four sunflower genotypes to boron levels and timing of foliar application. Each experiment comprised four sunflower genotypes (Euroflor , Record , Coban and ALbena) , three levels of boron foliar application (0,3 and 6 mg. l-1) , and three timing of boron sprayed on the plant leaves one dose during (6 leaves stage , budding stage and 50 % flowering stage) . They were conducted according to randomized completely block design with split – split plot with three replications. Results showed that the genotype Euroflor gave a high mean values of leaf area , head diameter , number of seeds / head , 1000 seed weight , seed yield and oil yield , while Albena genotype gave a high value of seed oil percentage for both seasons spring and autumn respectively. Boron sprayed on the plant leaves with concentration 3 mg. l-1 led significant increase in leaf area , head diameter , number of seeds/ head , 1000 seed weight , seed yield and oil yield , while increasing concentration of boron to 6 mg. l-1 increased seed protein percentage and protein yield. Delaying timing of boron foliar application to budding stage achieved highest values for most characters. Interaction genotypes x boron levels gave significant increase in leaf area , head diameter , number of seeds / head , 1000 seed weight and seed yield. Similar result were obtained from the interaction between boron levels x timing of boron application , further more, the same trend was recorded for seed oil percentage parameter. Moreover, genotypes x time of boron application, genotypes x boron levels x time of boron application had a significant affect on some characters under study.
