Could shading reduce the negative impacts of drought on coffee? A morphophysiological analysis

Abstract

Based on indirect evidence, it was previously suggested that shading could attenuate the negative impacts of drought on coffee (Coffea arabica), a tropical crop species native to shady environments. A variety (47) of morphological and physiological traits were examined in plants grown in 30-l pots in either full sunlight or 85% shade for 8 months, after which a 4-month water shortage was implemented. Overall, the traits showed weak or negligible responses to the light × water interaction, explaining less than 10% of the total data variation. Only slight variations in biomass allocation were observed in the combined shade and drought treatment. Differences in relative growth rates were mainly associated with physiological and not with morphological adjustments. In high light, drought constrained the photosynthetic rate through stomatal limitations with no sign of apparent photoinhibition; in low light, such constraints were apparently linked to biochemical factors. Sun-grown plants displayed osmotic adjustments, decreased tissue elasticities and improved long-term water use efficiencies, especially under drought. Regardless of the water availability, higher concentrations of lipids, total phenols, total soluble sugars and lignin were found in high light compared to shade conditions, in contrast to the effects on cellulose and hemicellulose concentrations. Proline concentrations increased in water-deprived plants, particularly those grown under full sun. Phenotypic plasticity was much higher in response to the light than to the water supply. Overall, shading did not alleviate the negative impacts of drought on the coffee tree.

PHOTOSYNTHETIC PERFORMANCE AND LEAF WATER POTENTIAL OF GULUPA (Passiflora edulis Sims, PASSIFLORACEAE) IN THE REPRODUCTIVE PHASE IN THREE LOCATIONS IN THE COLOMBIAN ANDES

“…This agrees with the fact that, in Granada, there are higher radiation, clear skies, and the soil is not water saturated (as was seen by the water soil content), which favor water uptake by the roots and its transport by the xylem due to the fact that it generates a high stomatal sensitivity to environmental changes (Rocha et al, 2004). Cavatte et al, (2012) reported that a low moisture content in the soil and high radiation in the day increase the nocturnal ability for hydration. When comparing the transpiration rate, the stomatal conductance and the water potential, a finer stomatal control was observed for Granada, evidenced by the fact that a slight decrease in stomatal conductance, caused a decrease in the transpiration that was clearly reflected in an increase in the water potential, which although also was observed in Chia, was less evident.…”

Physiological Responses to Hypoxia and Manganese in Eucalyptus Clones with Differential Tolerance to Vale do Rio Doce Shoot Dieback

“…In all the analyses, the quantity of blue light applied was 10 % of the photosynthetically active radiation (PAR), in order to maximize stomatal opening. More details were described by Cavatte et al (2012).…”

Efeito responsivo de mudas de paricá ao estresse hídrico

“…The total daily transpiration (TDT) was estimated by gravimetry, by means of the weight difference of the pots with a one-hour interval between 07:00 and 18:00 as described by Cavatte et al (2012).…”