摘要：Sunflower crop has an ability to maintain high level of viability in varying 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 2007 were conducted at Pir Mehr Ali Shah, Arid Agriculture University Rawalpindi, Pakistan to evaluate and document the oil and fatty acid accumulation in different circles/whorls of sunflower heads as influenced by varying environments. Sunflower hybrid S-278 was planted in randomized complete block design with four replications. Each head was divided into three equal circles (outer, middle and central) at maturity, thereafter, oil and fatty acid distribution was separately determined in each circle. Oil and fatty acid accumulated in three circles differed significantly. Outer circle accumulated higher oil content during spring which decreased to the minimum in central circle while, autumn season showed contrasting results in which oil contents progressively increased from outer to central circle. The maximum oleic acid was observed in outer circle which decreased to minimum in central circle during the both spring and autumn seasons, however, linoleic acid consistently increased from outer to central circle during both the seasons. Thus, oleic and linoleic acid depicted inverse relation with circles. Saturated fatty acid (palmatic acid and stearic acid) did not depict any consistent pattern for accumulation in different circles during both the seasons. Overall, spring planted crop exhibited significantly higher values for oil and oleic contents in comparison with autumn planting, which may be attributed to higher temperature, sunshine hours and accumulation of more growing degree days during the spring.
