Walnut Tree Pollen Quality in Cultivars with Various Flowering Times

Abstract

The increase in walnut tree crop is related to assortment, and also to good knowledge of biology in each cultivar. Walnut tree quality has a key role in choosing the pollination variety. A condition for doing a good pollination variety is to have good quality pollen, with high germination ability. Pollen quality is an important element on which flowers fecundation depends upon.. This paper proposed to study pollen in six walnut tree cultivars, having various flowering times. Local cultivars studied were ‘Germisara‘, ‘Roxana‘, ‘Mihaela‘, ‘Geoagiu 65‘, ‘Jupânesti‘ and ‘Orastie‘, all of them being considered to have good perspectives, owing to their fruit quality and high level of crops. Observations made were focused on flowering time, size of pollen grain, number of germinative pores, viability and germination of pollen grains, length of pollen tubes. Similar researches were conducted by de Luza J. G., V. S. Polito, (1985, 1988), G. Vergano, L. Radicati, I. Martino (1990), Pintea M. (1998), Sutyhemez M., S. Eti (2005) Research methods used were the ones recommended in the literature. Pollen grains size varied between 38.5 and 44.7 µ, the average number of germinative pores was 7, viability percentage was 96.9%, higher than germination percentage of 62.7%, and the average length of pollinic tubes was 159.5 µ, 12 hours after sowing. Variation limits for pollen grains and its viability are not in direct connection with flowering type. The results obtained were influenced both by cultivar, and by certain experimental and incidental factors.