Phenotypic plasticity of leaves and yield of pineapple grown under shade conditions

Abstract

The high temperature and solar radiation of the tropical regions can burn and reduce the fruits size of the pineapple. An alternative to the farmers of this crop is the shading of the plants, providing the climatic conditioning. Therefore, the objective was to evaluate the different shade conditions in the chlorophyll content and morpho-anatomy of pineapple leaves on fruit production. shading on the chlorophyll content, leaf morphology and anatomy, and pineapple productivity. The experiment was conducted in field and was of a randomized block design with four replicates of five treatments comprising 0% shading (pineapples grown in full sunlight), 45.0% shading (provided by adjacent cassava plants), 48.3% shading (provided by adjacent jack bean plants), and 30 and 50% shading (provided by shade netting). The anatomical, histological and biochemical characteristics of the leaves, along with the yield and percentage of sunburned fruits, were determined 16 months after planting the pineapples. Pineapples grown under natural shade provided by cassava or jack bean plants exhibited phenotypic plasticity with “D” leaves presenting trichomes of decreased length and vessel elements of reduced diameter. Under cassava shading, the thicknesses of the abaxial epidermis and chlorophyll parenchyma and stomatal density were increased, while the thickness of the aquiferous hypodermis and the percentage of sunburned fruits were reduced. Under jack bean shading, the thicknesses of the mesophyll, chlorophyll parenchyma and leaf blade were reduced. No significant differences in the yield of pineapple fruit were detected between treatments, although netting and shading by cassava produced significant reductions of sunburned fruit.