Effect of Nutrient Deficiencies on the Water Transport Properties in Figleaf Gourd Plants

Effects of nitrogen, phosphorus, and potassium deficiencies on water transport properties in figleaf gourd plants were studied. Plants were treated for different period of deficiency and physiological parameters such as stomatal conductance, photosynthesis and transpiration were measured. Cell and root pressure probes were utilized to measure turgor and root pressures, half-times of water exchange and hydraulic conductivities to analyze water transport properties. When plants were grown in nitrogen or phosphorus deficient nutrient solutions, they became insensitive to mercury, suggesting that aquaporin was closed resulting in reduced hydraulic conductivity. Inclusion of tungstate, however, restored the sensitivity of cells to mercury, indicating the importance of internal nutrient concentration, not the incoming nutrient supply. The hydrostatic hydraulic conductivity of roots grown in nitrogen deficient solution, representing apoplastic pathway of water transport, was reduced but this reduction was dramatically recovered by the application of tungstate, indicating the importance of nutrient availability from storage pools in relation to water status of plants.