Effects of Bagging and Nitrogen on Peel Color and Translucency in pineapple (Ananas comosus) Fruit
Date Issued
2012
Date
2012
Author(s)
Wu, Yi-Zhang
Abstract
Pineapple (Ananas comosus L) is prone to translucency disorder during summer in Taiwan and the translucency severity increase with fruit maturity. The yellowing of the peel color is the most important harvest index, which is related to chlorophyll degradation. Nitrogen application may delay the yellowing, which may because enhancing the peel chlorophyll production or retarding degradation. Since light is essential to chlorophyll synthesis, shading may speed color turning. Besides, high temperature may affect the degradation of chlorophyll and thus delay the color turning. Therefore, the objective of this thesis was to discuss the effects of urea application after forcing, temperature and shading on peel color turning. The effect of temperature on pulp translucency was also investigated.
The transmittance, temperature inside the bag and pulp temperature was altered by bagging. Black plastic bag (BPB) and transparent plastic bag (TPB) increased temperature inside the bag, where silver cloth bag (SB) decreased it. Application of 8g /plant urea after forcing delayed fruit peel color turning, 50% of peel turned yellow, 4-5 days in spring fruits and 3 days in summer fruits. In combination with the urea application and bagging treatment, TPB resulted in 5-6 days earlier in spring fruits, and BPB and SB resulted in 3 days earlier. The effect on peel color turning of the same
treatment in summer fruits was similar but less significant. In spring, temperature increase may affect color turning in addition to the effects of shading due to the spring temperature was not too high to hinder color turning. Temperature in the field of summer was usually above 40℃ which was unfavorable to color turning; thus, the delay was contributed by shading only.
The pulp translucency was not obvious in spring fruits but severe in summer fruits. Comparing the pulp temperature during the fruit development, it was lower than 35oC in spring fruits and exceeded 40℃in summer fruits. Pulp temperature may be a key factor for occurrence of pulp translucency.
High temperature may hinder the color turning of the peel and which might contribute the misjudge of fruit maturity; thus, the pulp of the summer harvested fruits may often accompany the occurrence of pulp translucency. In summer fruits, even though the color turning of BPB and SB bagged was similar, the fruits with pulp translucency was less and lighter in the SB bagged fruits indicated that lowering the fruit temperature may decrease the occurrence of translucency.
Subjects
pineapple
translucency
nitrogen
peel color turning
bagging
Type
thesis
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