Effects of foliar versus soil water application on ecophysiology, leaf anatomy and growth of pineapple

Abstract

In the subtropics, pineapple [Anan- as comosus (L.) Merr.] can be grown in plastic green- houses to avoid low temperature, which is the main

limiting factor to production outside of the tropics. Foliar water application and subsequent evaporative cooling can help avoid excessive leaf temperatures in

greenhouses during the hot seasons. The effects of fo- liar versus soil irrigation on ecophysiology, leaf anat- omy and leaf temperature of pineapple in protected

culture were tested to determine if the crop could re- ceive sufficient irrigation to avoid plant stress solely

from misting the foliage. Materials and methods – Rel- ative water content, relative chlorophyll content,

normalized difference vegetation index, membrane

stability, and cross sectional leaf anatomy were mea- sured at periodic intervals. Pineapple plants were

subjected to soil irrigation, misting and drought.

At the beginning and at the end of the experiment, to- tal leaf area, plant biomass and assimilate partition- ing to leaves, stems and roots were measured. Results

and discussion – The normalized difference vegetation index revealed differences among treatments after

fifteen days without irrigation. Pineapple plants en- dured thirty days of water stress without membrane

damage. Plants irrigated by applying water only to the leaves did not receive adequate water amounts and showed similar signs of drought stress as those of the non-irrigated treatment. Conclusion – Based on ecophysiological, anatomical and growth responses, soil water application alone is sufficient for avoiding water stress and excessively high leaf temperatures of pineapple plants grown in protected culture in the subtropics, whereas only misting the leaves does not provide