Optimum harvest moment and preservation of the seed of Andropogon gayanus cv. CIAT-621

Yolanda González Rosado
Estación Experimental de Pastos y Forrajes Indio Hatuey, Central España Republicana 44280, Matanzas, Cuba

ABSTRACT
A study was conducted on Andropogon gayanus cv. CIAT-621 to learn the optimum harvest moment of its seeds, as well as their germinative performance during storage and their response to different treatments. To study the optimum harvest moment, the seed was harvested 14, 21, 28, 35, 42 and 49 days after the massive onset of flowering. The highest production of pure seed occurred between 14 and 21 days (17,5 and 25,9 kg/ha, first harvest) and at 28 and 35 days (28,2 and 20,2 kg/ha, second harvest) in the first year; however, it was higher at 28 days (29,56 kg/ha, first harvest) and at 21 days (13,6 kg/ha, second harvest) in the second year. The production of fertile seed was higher at 21 days (4,02 kg/ha, first harvest) and at 28 days (10,11 kg/ha, second harvest in the first year; while in the second year it was higher at 28 days (12,11 kg/ha, first harvest) and at 21 days (5,07 kg/ha, second harvest). During the seed conservation, the highest germination percentages were obtained with the elimination of the glumes at 20 months of cold storage, with the same treatment at 8 months and when applying 5ºC during 15 days at 20 months of storage. Under ambient conditions, the highest value occurred with the elimination of the glumes at 8 months. The seed viability decreased during both types of storage and reached values of 0 and 80 % at 20 months under ambient and cold storage, respectively.
It is concluded that the seeds of this species should be harvested between 21 and 28 days after the massive onset of flowering, moment in which 90 % of them in their pure fraction, contain from 75 to 100 % of the maximum size. They show post-harvest dormancy associated to the glumes, which can be attenuated through a combination of treatments: if it is stored in refrigeration, by applying pre-cooling at 5ºC during 15 days before planting or eliminating the glumes; if the storage occurs under ambient conditions, they should be sown 8 months after harvest.