Requerimentos reprodutivos de duas culturas agrícolas no agreste pernambucano

Abstract

Phenology and reproductive biology assist in understanding the requirements of plants grown for the formation of fruits and seeds as well as in the management of pollinators when needed. This study aims to investigate the phenology and the reproductive biology Macadamia integrifolia (Proteaceae) and the tangelos Nova and Lee in the Experimental Station of the Agronomic Institute of Pernambuco (IPA), the municipality of Brejão (PE). The vegetative and reproductive phenophases of M. integrifolia (n = 7), tangelo Nova (n = 6) tangelo Lee (n = 6) were followed every two weeks from July / 2014 to June / 2015. The intensity of flowering and fruiting were estimated, the pattern of flowering was described and the correlation between rainfall and the occurrence of phenophases was tested. The investigation of the floral biology included analysis of anthesis period, stigmatic receptivity, as well as pollen and nectar availability. The reproductive system was determined by means of controlled pollination in the field. The floral visitors and their frequency of visits were determined by means of focal observations. The results are distributed in two chapters: The first one regarding M. integrifolia and the second one regarding the tangelos. In the first chapter the phenological events were not influenced by rainfall. Lepidopterans, himenopterans and dipterans were the most frequently observed visitors, which visited in low frequency. The species is self-compatible, had low fruit set, low reproductive efficiency and pollen limitation. In the second chapter, the varieties showed similar phenological patterns. Flowering occurred three times, with a peak in December (dry period), and there was no significant correlation between precipitation and analyzed phenological phases. The varieties have terminal inflorescences, hermaphroditic, actinomorphic flowers that were visited by Hymenoptera, Diptera and Lipidoptera species; bees were the most frequent. Both plants are self-compatible and the fruits resulted from and the fruits resulted from cross-pollination has similar to those resulted from the natural pollination. Pollen limitation and a low reproductive efficiency were observed, a result that may be related to the frequent pesticide spraying. These compounds may cause floral abcision and reduce pollinators‟ populations (and, consequently, fruit set), especially in plants that need pollinators to.