EFFECT OF DIFFERENT LEVELS AND TIMING OF BORON FOLIAR APPLICATION ON GROWTH, YIELD AND QUALITY OF SUNFLOWER GENOTYPES (Helianthus annuus L.
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) 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 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 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. INTRODUCTION The importance of boron deficiency for sunflower has been reported by Blamey (1976) and Chatterjee and Nautiyal (2000) Boron fertilization of sunflower on soil with a ph 4.9 resulted increased yield and seed oil content for two genotypes (Brown and Hu, 1997) Concomitant with the increased oil content, protein content for one cultivar was significantly decreased by boron fertilization. The decrease in protein content was not as great as the increase in oil brought about by boron fertilization, presumably indicating a change in the kernel to hull ratio. Even in conditions where seed yield was not affected by boron fertilization higher levels of boron reduced seed oil content Received 17/2/2010 accepted 20/9/2010 Mesopotamia J. of Agric. (ISSN 1815 316X) Vol.(39 No.(3) 2011 17 (Beauguillaume and Cadeac, 1992) (Bredenhann, 1999) High boron supply after anthesis resulted in lower seed oil and higher protein contents (Meszaros and Simits, 1992) also found a decrease in seed oil content with increasing levels of boron application. Baldini and vannozzi (1996) have found that an increased supply of boron improves hull ability. The aim of the present research was to through some light on the factors which govern the effect of different levels and timing of boron foliar application on growth yield and quality of sunflower genotypes. METERALS AND METHODS Two field experiments were conducted at AL Rashidia location 20 km in the west north Mosul city Nineveh province during two successive growing seasons of 2008: spring and autumn, in a sandy loam soil to study the effect of different levels and timing of boron foliar application on growth yield and quality of sunflower genotypes. Each experiment comprised four sunflower genotypes (Euroflor, Record Coban and ALbena) with three levels of boron foliar application(0,3 and 6 mg. l) and three timing of boron application (6 leaves stage budding stage and 50 flowering stage) The experimental design was split split plot in a randomized completely block design with arrangement keeping with genotypes as main plots the sub plots were assigned to boron foliar application, while timing of boron application as sub sub plots with three replications according to Steel and Torrie (1980) The Duncans multiple range test (Duncan, 1955) was used to compare among means (Anonymous,2001) A representative soil sample (0 to 30 cm depth) was taken before planting (Table 1) using the methods description by Black (1985) Page et al.(1982) and Tendon (1999) Boron determined by Jac kson Table (1) Some physical and chemical characteristics of the experimental site. Autumn season Spring season Soil analysis I physical analysis: