The
aim of this experiment is to search best concentration of GA and appropriate
duration (soaking hour) as well as to find out best interaction between best
concentration and best soaking duration. Soaking the seeds with 10-5 M GA for 8 h is best for growth and development of
sunflower cv. PAC 3776. Surface sterilized seeds sunflowers (Helianthus annus L.) were soaked in 0, 10-7, 10-5 and 10-3 M aqueous solution of gibberellic acid (GA) for 4, 8,
12 and 16 h and sown in pots filled with 4 kg homogenous mixture of soil and
farmyard manure in the ratio of 4:1. The plants were sampled at 50 and 70 days after
sowing (DAS), for analysis of shoot and root dry weight, leaf area index (LAI),
carbonic anhydrase activity (CA) and nitrate reductase (NR) activity, nitrogen
(N), phosphorus (P) and potassium (K) content at 50 and 70 DAS and seeds per
head, seed yield, and harvest index, acid value, iodine value and
saponification value at harvest (90 DAS). All parameters were found to be
significantly enhanced by the GA seed priming effect, with maximum stimulation
being noted following an 8 h soaking treatment with 10-5 M GA. Moreover, the most of the mentioned parameters were enhanced by 132.98%,
170.59%, 33.82%, 25.86% and 86.14% over the control at the 50 DAS except the
CA, N, and P found to be non-significant at this stage. N content was found to
be non-significant also at 70 DAS. Similarly, yield parameters were enhanced
also by 123.49%, 44.76%, 41.38%, 111.76% and 1.64% respectively at harvest over
control except iodine value. The objective of this experiment is to enhance the
quality of sunflower constituents through application of best concentration and
soaking time of GA.