Effects of soil water deficit on gas exchange characteristics and water relations of orchard lychee (Litchi chinensis Sonn.) trees

• Published in: Tree physiology Vol. 14; no. 10; pp. 1177 - 1189
• Main Authors: BATTEN, D.J, MCCONCHIE, C.A, LLOYD, J
• Format: Journal Article
• Language: English
• Published: Victoria, BC Heron 01.10.1994
• Subjects: Agronomy. Soil science and plant productions; agua del suelo; Biological and medical sciences; biological rhythms; drought; drought stress; eau du sol; echange gazeux; Economic plant physiology; estoma; estres de sequia; feuille; Fundamental and applied biological sciences. Psychology; gas exchange; hojas; intercambio de gases; irrigation; leaves; Litchi chinensis; plant water relations; relaciones planta agua; relation plante eau; riego; ritmos biologicos; rythme biologique; seasonal variation; secheresse; sequia; soil water; stomata; stomate; stress du a la secheresse; transpiracion; transpiration; variacion estacional; variation saisonniere; Water relations, transpiration, stomata; Irrigation; Litchi chinensis; Fruit; Water deficit; Stomatal conductance; Water stress; Abscission; Transpiration; Fruit crop; Dicotyledones; Angiospermae; Sapindaceae; Spermatophyta; Fruit tree; Gas exchange
• ISSN: 0829-318X; 1758-4469
• DOI: 10.1093/treephys/14.10.1177

Eight-year-old Iychee (Litchi chinensis Sonn.) trees, cv. 'Bengal,' growing in krasnozem soil were subjected to soil water deficit from one month before flowering until harvest by covering the ground with polyethylene sheeting and withholding irrigation. The ratio of daytime stomatal conductance of unirrigated to irrigated trees decreased 20% during the three months of increasing water deficit. Predawn leaf water potentials of irrigated trees averaged about -0.3 MPa throughout the period, whereas they declined progressively to -0.9 MPa in unirrigated trees. Minimum daytime leaf water potential in the unirrigated trees decreased from -1.0 to -1.1 MPa at the beginning of the drought period to -2.2 to -2.4 MPa after three months, and calculated whole-plant conductance did not change with decreasing availability of water. The calculated soil-root water potential declined to less than -1.0 MPa in unirrigated trees. Capacitance effects on the relationship between leaf water potential and transpiration were significant only at low transpiration rates. Although unirrigated trees reduced soil water content at 0-30 cm depths to an equivalent water potential of -1.0 MPa, fruit shedding was significantly less than in irrigated trees. Water deficit had no effect on the fresh weight of pericarp, but caused increased seed size and decreased fresh weight of flesh, resulting in fruit from unirrigated trees being 16% lower in total fresh weight per fruit than fruit from irrigated trees.