Stomatal behavior and water relations of chilled phaseolus vulgaris cultivar masterpiece and pisum sativum
Eamus, D.; Fenton, R.; Wilson, J.M.
Journal of Experimental Botany 34(141): 434-441
ISSN/ISBN: 0022-0957 Accession: 006484747
Leaf diffusion resistance interpreted as stomatal resistance, leaf water potential (.PSI.w), solute potential (.PSI.s) and leaf turgor potential (.PSI.p) of the chilling sensitive species P. vulgaris were determined during chilling at 4.degree. C in the light. Chill-hardened and non-hardened plants were used. For comparison, the chilling resistant species P. sativum was also used. The results for chilled P. sativum were similar to those obtained for chill-hardened P. vulgaris plants receiving a chilling treatment. In both cases, a reduction in stomatal aperture and the maintenance of a positive leaf turgor were the responses to chilling. Leaves of chilled but non-hardened P. vulgaris plants maintained open stomata throughout the chilling treatment despite a severe wilt developing after 7 h at 4.degree. C. This was in contrast to the chill-resistant P. sativum, which showed a rapid closing and subsequent re-opening of the stomata to a new reduced aperture. During the first 12 h of chilling .PSI.w of P. vulgaris leaves changed from -0.47 MPa [mega pascals] to -1.24 MPa. On more prolonged chilling, .PSI.w tended to return to pre-chilling values. .PSI.p decreased from 0.42 MPa to zero after only 9 h of chilling, and remained at this value for the remainder of the chilling period. .PSI.s changed rapidly from -0.89 MPa to -1.35 MPa in the first 7.5 h, and after 9 h, .PSI.w and .PSI.s were equal, i.e., zero .PSI.p. The chilling resistant plant P. sativum maintained a positive .PSI.p throughout the chilling period, and there was little difference between values of .PSI.w and .PSI.s in control and chilled leaves.