REPRODUCTIVE CHARACTERISTICS AND SEED QUALITY IN FRAGMENTED POPULATIONS OF Pinus chiapensis (MARTÍNEZ) ANDRESEN

Abstract

Pinus chiapensis (Martínez) Andresen is a fast-growing tree, appreciated for its wood quality, whose northern populations, in the state limits of Puebla and Veracruz, Mexico are small, fragmented and with reduced regeneration. The objective of this study was to characterize some reproductive traits associated with regeneration of seven Pinus chiapensis populations in these states. A total of 125 trees were sampled (15 to 22 trees per population) and the seed harvested from a sample of 10 mature cones per tree was evaluated. The length, width and dry weight of the cones, the potential for seed production, percentages of filled, empty and plagued seeds, aborted ovules and the average weight of the seed were determined. A germination test was carried out in a controlled-environment chamber. Significant differences were detected between populations in all variables evaluated. The average cone length and width were 95.9 and 28.7 mm, respectively; both positively correlated with the altitude of origin of the population. The average potential number of seeds per strobilus was 89, of which 59.0 % were aborted ovules, 22.6 % empty seeds, 0.9 % plagued seeds and 17.5 % filled seeds, which indicates a low efficiency of seed production (1 to 16 filled seeds per cone). The high percentage of aborted ovules indicates pollination problems associated with the small size of the populations. A reproductive efficiency of 25.6 mg of seed per gram of strobilus was found. The seed showed a germination capacity of 75.7 %, a peak value of 3.74 % per day and a germinative value of 9.74. Despite the low production of filled seeds and the high percentage of empty seeds, the evaluated populations produce filled seeds of acceptable germination quality.