Produção, qualidade e efeitos microclimáticos no cultivo de tomate industrial em diferentes coberturas do solo no município de Baraúna - RN

Abstract

Two experiments were conducted from July to November 2008, and from September 2009 to January 2010 at WG FRUTICULTURA Farm in Barauna, State of Rio Grande do Norte, Brazil. The aim was to evaluate yield, quality and microclimatic effects in the processing tomato cultivation with different mulching. The experimental design was complete randomized blocks with four replications. The treatments were arranged in split plots, and they were represented by the type of mulching: non-covered (control), black polyethylene film, silver polyethylene film (double-sided black and silver), white polyethylene film, and black polypropylene (non-woven textile NWT). The subplots were represented by the type of hybrid tomato: SM-16 and Mariana, both with dual purpose, fresh and industrial consumption. The attributes evaluated were: number of marketable fruits per plant (NMF), number of unmarketable fruits per plant (NUF), total number of fruits per plant (TNF), commercial yield (CY), unmarketable fruits yield (UFY), total fruits yield (TFY) and mean weight of marketable fruits (MWMF). The hybrid SM-16 presented higher marketable fruits yield; the black and silver polyethylene provided the lowest marketable fruits yield; the tomato grown with white polyethylene provided greater profitability. The attributes evaluated were soluble solids and total soluble sugars, titratable acidity, vitamin C, pulp firmness and soluble solids/titratable acidity. The types of mulching did not affect the percentage of soluble solids, total soluble sugars and total soluble sugars/titratable acidity; the black polypropylene provided the highest levels of vitamin C and titratable acidity; the non-covered soil and black polyethylene film presented the lowest levels of vitamin C and titratable acidity, respectively; the hybrid SM-16 presented firmer fruits than the hybrid Mariana. To evaluate the effect of microclimate of each type of mulching, four micrometeorological towers were distributed in the useful area on the various treatments from August 28th to November 13th 2008. The attributes evaluated were: global solar radiation, net radiation, soil heat flux at 2.0 cm depth, and soil temperatures at 2.0 cm depth and air ones at 50 cm from the surface (°C). In the second experiment, from September 1st 2009 to January 11th 2010, because of the availability of tools, the air and soil temperatures monitoring was only possible under the same conditions of the first experiment. The white polyethylene and non-woven textile presented the highest and lowest intensity of reflected radiation (6.86 MJ m-2 and 5.93 MJ m-2), respectively; the non-covered soil and NWT presented the largest variations of the soil heat flux; polyethylene films provided the largest daily variation of the soil temperature than NWT and non-covered soil