Effect of stratification, gibberellic acid (GA3) and promalin on the germination of Pistacia atlantica Desf. seeds [germination percentage; seedlings height; number of leaves; root length; shoot and root dry weight].

Four experiments were conducted in 1992-1993 in an attempt to improve the germination percentage of Pistacia atlantica Desf. seeds using 0, 2, 4, 6 and 8 weeks of stratification at 4-6 C in combination with different GA3 (0, 250, 500, 750, 1000 or 1250 ppm) or Promalin (0, 250, 500, 750, or 1000 ppm) concentrations. Experiment 1: stratification had no significant effect on germination percentage, seedling height, number of leaves, root length, shoot and root dry weight of P. atlantica. The effect of GA3 on germination percentage, seedling height, root length and dry weight seems to be concentration dependent. Shoot dry weight was significantly improved by GA3 at all concentration levels compared with the control; number of leaves on the contrary was not significantly affected by GA3 concentration. The interactive effects of stratification and GA3 were only significant with respect to seedling height, shoot and root dry weight. Experiment 2: germination percentage, seedling height, number of leaves, root length, shoot and root dry weight of Pistacia atlantica were in most cases not significantly improved by the different stratification duration. The effect of GA3 was either insignificant (germination percentage) or concentration dependent (seedling length, number of leaves, root length, shoot and root dry weight). Furthermore, the letter two parameters (shoot and root dry weight) in most cases significantly decreased by increasing GA3 concentration. The interactive effects were significant with respect to seedling height, number of leaves, root length, shoot and root dry weight. Experiment 3: only two parameters (number of leaves and root dry weight) were significantly improved by all stratification durations, while the other parameters did not respond significantly, in most cases, to the different stratification periods. GA3 at all concentration levels significantly improved shoot and root dry weight per seedling, while its effect on the other parameters (germination percentage, seedling height, number of leaves and root length) was concentration dependent. Furthermore, the interactive effects with respect to number of leaves and root length were significant, while insignificant with respect to germination percentage, seedling height, shoot and root dry weight. Experiment 4: the different stratification durations and the different Promalin concentration levels failed in most cases to cause a significant improvement of germination percentage, seedling height, root length, number of leaves, shoot and root dry weight. The only exception was root dry weight which was significantly increased in response to the different stratification durations. The interactive effects were significant with respect to seedling height, number of leaves, root length, shoot and root dry weight, while they were insignificant with respect to germination percentage.