Effect of gibberellic acid on breaking post harvest dormancy in seeds of Zea mays L

The experiment was conducted during Summer 2012 in (Lab. Experiment: In laboratory seed technology - Field Crops Department / Collage of Agriculture - Green Qassim University) and (Field experiment: in one field of Abo-Gharaq / Babyonl), to investigate the response of synthetic Maize variety(Buhooth 106) to different planting Date and different levels Gibberellins(GA(3)), A split plot arrangement in randomized complete block design, with three replication was used. The treatments Were three planting Dates (D-1, D-2 and D-3) with five levels of Gibberellins GA(3) (0, 25, 50, 75, 100 and 200) ppm. significant differences were found among planting Dates and Gibberellins levels with Their interactions for same the studied traits. The Lab Experiment in treatment third date (D-3) was superior in germination percentage (64%), germination period (3.491 day/seed) and germination action (36.97%); So Gibberellins level (100ppm) was superior in germination percentage (89.33%), germination period (3.328 day/seed), coefficient speed germination (29.93) and germination action (35.27%); Overlap among the traits found(D-3 * 100ppm Gibberellins) in germination percentage (94.33%), germination period (3.063 day/seed), coefficient speed germination (32.80) and germination action (40.13%). The field experiment in treatment third date (D-3) was superior in leaf area (530.13 cm(2)), grain weight (188.47 mg), plant biological yield (277.17 g) and plant grains yield (99.40 g) and harvest index(35.82%), So Gibberellins level (100ppm) was superior in leaf area ( 577.78 cm(2)), No. of grains/kernel (565.78), grain weight (195.22 mg), plant biological yield (267.66 g), plant grains yield (101.56 g) and harvest index (37.91%). A linear relationship was found between studied traits and both planting Date and Gibberellins levels (D3 * 100ppm Gibberellins) in leaf area (608 cm(2)), No. of grains/kernel (589), grain weight (204 mg), plant biological yield (288.90 g), plant grains yield (112.69 g) and harvest index (39%).