Morpho-Genetic Expression of Sunflower Under Varied Temperature and Moisture Regimes.

Sunflower is a potential crop for rainfed ecology that can help meet the edible oil needs of the country. In vitro and in vivo experiments were conducted during 2003 and 2004 at the University of Arid Agriculture Rawalpindi. In the laboratory, a study was conducted to determine the effect of temperature and moisture stress on the germination of sunflower hybrids. Five hybrids (Super 25, Parsun-1, SMH 9706, Award and Hysun-33) at six temperature (10,15,20,30,35C) and three moisture levels (0,-7,-14 bars) were tested in the experiment. The maximum germination rate was observed at 20 and 25C at O bar in all the hybrids, at 10C very poor germination was recorded at -7bar while at -14 bar there was no germination at 35C. These result proved that a temperature range of 20- 30C is conducive for germination, while moisture level of O bar to -7 bars is reasonably good In the Field experiment the same sunflower hybrids were planted on 11th, 23rd July, 6th , 16th , 26th, August during autumn and 16th February, 3rd , 15th March, 9th , 27th, April during spring in randomized complete block design with plit plot arrangements replicated three times.Planting dates were kept in the main plots and hybrids in subplots. Sunflower hybrids exhibited significant differences for heart unit accumulation during both the seasons (autumn, spring). The hybrid Hysun-33 remained on the top for heat units, this provided the clue that Super-25 is an early maturing and Hysun-33 is late maturing hybrid, however, all the hybrids gained more heat units in the spring season as compared to autumn. Among the planting dates, the significant differences were found in both the seasons for heat units accumulation. In autumn, the 11th February planted crop gained the maximum heat units. The results showed that the crop consuming the maximum heat units gave the maximum yield during both the seasons. Significant differences were found for all the growth and yield attributes among the hybrids during both the seasons. The maximum yield was recorded for Hysun-33 during during both the seasons. Planting date also influenced the growth and yield attributes significantly. The maximum yield was obtained from the crop planted on 11th of July during autumn and 16th of February during spring seasons. However the spring planted crops performed better for yield and yield attributes. Sunflower hybrids exhibited significant differences for oil and fatty acid composition. During autumn, amongst hybrids, Hysun-33 performed better for oil and oleic acid while Award remained at the top for plasmatic and linoleic acid. However, during speing, Super-25 accumulated the highest oil and linoleic acid while Hysun-33 was the best for stearic and oleic acid. Planting dates also influenced oil and fatty acid composition significantly. Overall, spring plantation accumulated higher oil and oleic acid in comparison with autumn planting. However, autumn planting accumulated less oil but higher linoleic acid that depicted an inverse relationship of oleic and linoleic acid. During autumn, late August planting accumulated the maximum linoleic and the minimum oleic acid. During speing, late April planting exhibited the highest oleic and least linoleic acid.