Evaluation of the vigor of Albizia lebbeck (L.) Benth. seeds during seedling emergence

Marlén Navarro Boulandier
Estación Experimental de Pastos y Forrajes Indio Hatuey, Central España Republicana 44280, Matanzas, Cuba

ABSTRACT
During three years seeds were collected from the same mother plantation of A. lebbeck; the first stage of the research was focused on evaluating the effect of storage on germination and viability, as well as on identifying and characterizing the dormancy period in this species. The viability and germination reached their maximum expression at the beginning of the study (99,75 and 46,90 %, respectively); when comparing the values of these parameters during the 11 months of storage, remarkable differences were observed among them, because A. lebbeck seeds reinforce the impermeability of their seed coats since two months after the beginning of the storage stage. In order to determine the influence of the storage time (ST) and the sowing conditions (SC) on seedling emergence, a second stage was conducted, from the mathematical adjustment of the modified Weibull equation. For the germination rate (k) the highest values were found in treatments A (12,01 %) and B (8,92 %) when the seeds were sown at 5 and 9 months after the beginning of storage (mabs). The delay of the seeds to germinate (Z) showed significant differences for the values in C with regards to the sowing in A and B (3,0ab; 1,25a and 4,5c for A, B and C, respectively). The highest percentage of M was observed in the sowing performed at 5 mabs (48,0a %) in treatment A. The results of the factorial arrangement highlight maximum temperature as the value with the highest relation to the performance of seedling emergence. The third stage consisted in the study of the effect of different pregerminative treatments focused on breaking dormancy on seedling emergence in the experimental nursery. In the control treatment the highest value of seedling emergence was observed at 5 mabs (49,33 %), and between 9 and 11 mabs a drastic reduction of this indicator occurred; when cutting the seed coat before sowing at 0, 2and 5 mabs the highest percentages are obtained (88,0a, 79,67ab and 73,33ab %, respectively); the effect of puncturing the seeds was beneficial in all the evaluations because even in the least one (11 mabs) a value higher than the one recorded for the seed coat cut in the same period. The immersion of A. lebbeck seeds in water at ambient temperature during 24 hours only exceeded the control treatment in the evaluation corresponding to 11 mabs (6,0 vs 2,0 %). The cluster analysis defines the seeds of the evaluation that links the coat cut and the beginning of the storage stage (CCo) as the ones with the highest vigor, followed by the treatment that consisted in puncturing the seed coat at 0 mabs and the coat cut at 5 mabs.