Relationships of Soil Moisture Stress to Different Aspects of Growth in Ladino Clover

Abstract

AbstractThe relationships of soil moisture content or soil moisture stress to growth in Ladino clover have been investigated in containers under controlled environmental conditions and in field plots. Relationships involving the following aspects of growth or plant functioning are reported: (1) transpiration rate, (2) green weight production, (3) dry weight production, (4) dry matter percentage, (5) shoot elongation, (6) photosynthesis rate, (7) respiration rate, (8) chemical composition, (9) flower formation (number and size), and (10) seed production.Dry weight production of vegetative material, photosynthesis, and respiration rates were not affected appreciably until the moisture content in the entire root zone approached the permanent wilting percentage. Green weight production and shoot elongation were reduced significantly when the soil moisture content fell into the lower half of the available range. Chemical composition, flower formation, and seed production were also influenced by moisture conditions within the available range.The different relationships obtained illustrate that the increasing soil moisture stress experienced by Ladino clover as the readily available moisture is depleted does not have a uniform effect upon various aspects of its functioning and growth. Thus there is no one simple and general relation between soil moisture conditions and all aspects of plant functioning. Some plant processes are relatively insensitive to increasing moisture stress over the available range while others are distinctly affected. Such soil moisture‐growth relationships are also dependent upon plant characteristics, soil conditions, and climatic factors. Information on these relationships should suggest opportunities for more effective irrigation by considering both the soil moisture stress and the physiological stage of plant development in the timing of water applications.