Impacts of shading in field on micro-environmental factors around plants and quality of pineapple fruits.

The aim of the current research was to investigate the impacts of shading on micro-environmental factors and quality of pineapple fruits. The shading experiments were conducted in the field in 2010 with a pineapple cultivar Yueyinaoka categorized cayenne as material. Field-grown pineapple plants were shaded severely (S1, about 25% of nature sunlight) and slightly (S2, about 75% of nature sunlight) when the fruits were about 6 cm in width in horizon (about 30 days after blossom), respectively. Plants growing under natural sunlight were considered as control (S0). Micro-environmental factors (temperature and relative humidity) around plants, chemical quality and aroma components of pineapple fruits were measured. The results indicated that temperature was decreased and RH (relative humidity) increased in some degree after shading. Compared with S0, temperature of S1 was decreased by 2oC to 4.5oC in the whole day, RH of S1 was increased by 0.5% to 6.0%. Temperature of S2 was decreased in a low degree by 1oC to 1.5oC in the whole day. RH of S2 was really close to that of S0 in the whole day, especially at noon. The chemical quality of pineapple fruit was somewhat decreased by shading treatments. Compared with S0, TSS and contents of total sugar in the fruits of S1 and S2 were declined, especially in S1. The contents of total acid of S1 and S2 were both increased compared with S0, but not significantly. There were more kinds of aroma components detected in the pineapple fruits of shading treatments, but the major added aroma components identified in S1 and S2 were alkenes with higher total relative contents. The total contents of ester aroma components of S1 and S2 were both lower than that of S0. In addition, the characteristic aroma component of pineapple fruits, propanoic acid 3-(methylthio)-methyl ester, was only identified in the fruits of S0, and not in S1 and S2.