Revista Brasileira de Milho e Sorgo (Aug 2007)
CONSERVATION AND DETERMINATION OF THE VIABILITY OF MAIZE POLLEN GRAIN
Abstract
In maize breeding programs, factors related to receptivity length of stigma, longevity of pollen grain in the plant, differences in the period of blossoming among plants and conservations of the genetics resources are some aspects that reinforce the importance of pollen grains storage. In this research the influence of water tenor, period and storage environment were evaluated in regard to the viability and germination of maize pollen grains. The assays took place in laboratories of Analyses of Seed Molecular Biology of the seeds sector and in the experimental area of Agricultural Department of UFLA. In the pre-tests, different culture methods were verified to evaluate the in vitro germination as well the best time to collect the pollen grains. The germination pollen grains in different water tenors was also evaluated: 51,7%; 29,4%, 21,7%; 17,7%; 17%. In a second experiment the pollen grains with water tenors of 51,7%; 29,4%; 21,7% were stored in deep freezer (-86oC), fridge (4oC), and liquid nitrogen (-193oC) for 14 and 30 days. After the storage, the germination and viability of pollen grains were evaluated in vitro in culture medium and through the tetrazoilium test, respectively. The viability of stored pollen grain for 14 days in different water tenors and storage places/environment was also tested in vivo through auto fecundation in plants of Le-57 inbred lines and GNZ 2004 hybrid, when both showed receptive style-stigmas. For the evaluation of germination and viability of pollen grains, a completely randomized design was used, in factorial scheme 2 (period of storage) x 3 (water tenors of pollen grains) x 3 (places storage), with four repetitions. In the pre-tests higher values of germination of pollen grains were observed in culture medium containing 10% sucrose; 0,03% boric acid; 0,15% calcium chloride (M2), and when the collection took place at 9 a.m. the viability of pollen grains was reduced substantially below 21,7% of water tenor indicating they don’t tolerate the desiccation. For a better conservation during the storage, the pollen grains should be dried until 21,7% of water tenor and storage in liquid nitrogen.
