Interaction soil compaction and soil moisture in physiological responses of freshly planted coffee

Abstract

In the field, coffee is subject to the stress of soil compaction and lack of water, which may cause changes in the physiological responses of the plant. The objective of this study was to evaluate the physiological responses of the coffee tree under different soil moisture content and compaction degrees in the soil subsurface. The experimental design was in blocks, arranged in a factorial scheme, with four replications. The first factor corresponds to the two wetlands, 50 and 100% of the soil field capacity. The second factor corresponds to 60, 70, 80 and 90% of soil subsurface compaction. The experimental plot consisted of a Coffea arabica L. plant grown on a polyvinyl chloride column. The physiological responses were evaluated at 180 days of planting. The photosynthetic rate, carbon consumption, CO2 concentration in the substamatic chamber, internal carbon / atmospheric carbon ratio, water efficiency and absolute coffee growth rate were influenced by the different compaction degrees and soil moisture content. The transpiration rate and the root weight ratio were influenced only by the humidity, as opposed to the stomatal conductance and the foliar temperature, which were by degrees of compaction. The ratio of root system per soil layer was influenced by compaction degrees and soil depth. The limitation of root growth and lack of water are the main causes of the decrease in physiological responses. Subsurface compaction and water deficit together potentiate the effect negatively on the physiological responses of freshly seeded coffee plants.