Papaya seedlings, cv. Baixinho de Santa Amália ("Solo" group), were transplanted to three contiguous structures: (a) greenhouse (plastic covering), (b) shadowed greenhouse ('sombrite' net - 30%, over plastic sheet), and (c) screen house ('sombrite' net - 30%, exclusively), established side-by-side in an area for papaya cultivation under natural conditions. The greenhouse lateral and frontal parts were protected with anti-aphid screen. At transplanting and subsequently in mensal intervals, during the first cropping year, plants were monitored in relation to: height, basal trunk diameter, number of active leaves, and foliar area. Cultural practices were according to technical regulations of the Brazilian law of organic agriculture. Since the initial harvesting, all fruits produced were counted and weighted. Compared with the natural environment, protected cultivation induced increases in plant height (20%). In the greenhouses, particularly in the one without additional covering of 'sombrite', stimulatory effects also occurred, relating to trunk diameter (30%), leafing index (20%) and foliar area (36%) on each evaluation date. Organic papaya cultivation in greenhouses made possible highly significant surplus in marketable fruit yield (67% from weight and 49% from number) within the research period. In addition, cv. Baixinho de Santa Amália had not reached the greenhouses roof (4,5m) by the last quantified harvest, allowing to estimate, based on the linear growth rates registered, a productive cycle exceeding two years under protecting structures.
Carica papaya L.; protected ambient cultivation
