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Photosynthesis and Water Vapor Exchange of Pigeonpea Leaves in Response to Water Deficit and Recovery
Author(s) -
Lopez Francis B.,
Setter Tim L.,
McDavid Charles R.
Publication year - 1988
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1988.0011183x002800010030x
Subject(s) - photosynthesis , stomatal conductance , water stress , biology , horticulture , transpiration , water use efficiency , osmotic pressure , vapour pressure deficit , botany , agronomy
Pigeonpea [ Cajanus cajan (L.) Millsp.; cv. UW‐10], a crop being developed for use in low‐rainfall environments, was studied during development of water stress and recovery after rewatering to determine the treatment effects on photosynthesis and leaf diffusive conductance. Plants were grown in a greenhouse and leaf gas exchange was measured at various photosynthetic photon flux densities during an 8‐d period of water stress development and during an 18‐d period of recovery following rewatering. Predawn total water potential (ψ w ) declined by 1.0 MPa after 8 d of withholding water, whereas the pressure component of water potential (ψ p ) remained positive due a decrease in the solute component of water potential (ψ p ) from −1.2 to −1.7 MPa. During stress development, decreases in leaf diffusive conductance ( g L ) occurred earlier than decreases in photosynthetic CO 2 exchange rate (CER), indicating that a water conservation mechanism was induced. Differences in g L between unwatered and control plants were first detected at 5 d after withholding water. Differences in CER between control and unwatered plants were not detected until Day 8 of the treatment. As a result of these CER and g L changes, the CO 2 concentration in the intercellular air space ( C i ) decreased during the period from 5 to 8 d after withholding water. After rewatering, CER and gL slowly recovered over an 18‐d period. It is concluded that pigeonpea responds to water stress by partially limiting the rate of water loss and maintaining a low CER, and it responds to rewatering by slowly recovering CER and g L .