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SEED AND OIL DISTRIBUTION IN DIFFERENT CIRCLES OF MATURE SUNFLOWER HEAD

SHUAIB KALEEM   AND FAYYAZ-UL-HASSAN*

Abstract: High degree of adaptability, wide range of climatic conditions, high photosynthetic capacity and harvest index allow sunflower crop to be productive in broad range of environments. Prevailing temperature at pollination and after anthesis affects pollen health, fertilization process and ultimately the seed filling and assimilate partitioning that varies in different circles/whorls of sunflower heads.   Field experiments one each in spring and autumn were conducted at Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi, Pakistan to document  the assimilate partitioning (as achene) and oil accumulation in different circles/whorls of sunflower heads as influenced by varying environments. Four sunflower hybrids were planted in randomized complete block design with two factors factorial (hybrids & circles) experiment with four replications. Each head was divided into three equal circles (outer, middle & central). Achene and oil distribution was separately recorded in each circle. All four hybrids produced heads of larger diameter in spring crop than those produced by autumn season crop. Outer circle produced higher number of achenes, those were heavier in weight and accumulated higher oil content in all four hybrids as compared to middle and central circle in spring crop, while oil content showed minor increase from outer to central circle in autumn crop, which showed the least number of rows and hull kernel ratio. Hull kernel ratio showed contrasting results as compared to other traits which progressively increased from outer to central circle in spring crop while consistently decreased in autumn crop in all the four hybrids. Number of achene, achene weight, hull kernel ratio and oil content in all three regions (outer, middle and central) of spring sown sunflower heads were more than those of autumn crop heads. Opposite relationship between head circles, hull kernel ratio and oil content was observed for both the seasons.

Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi, Pakistan