The objective of this study was to investigate the influence of water stress conditioning on the photosynthesis response of switchgrass (Panicum virgatum L.) and tall fescue (Festuca arundinacea Schreb.) to moisture deficiency. Tillers of the two species were grown in the same, controlled, environment and were subjected to three conditioning water stress cycles, or were kept well watered. After drought conditioning all plants were subjected to moisture deficiency while photosynthesis and leaf water potential were monitored. Measurements were taken between –0.8 and –4.0 MPa and the rate of water stress was 0.49 MPa/day. The conditioning of switchgrass produced a 26% reduction in the photosynthesis rate during drought, while that of tall fescue produced a 57% reduction in photosynthesis. Both species maintained elongation and photosynthesis down to lower leaf water potentials after drought conditioning than before conditioning. The conditioning water stress cycles decreased the leaf conductance, mesophyll resistance and transpiration of tall fescue plants after rewatering. The leaf water potential of conditioned switchgrass plants was lower upon rewatering after three conditioning water stress cycles than the leaf water potential of non-conditioned plants, while the leaf conductance, mesophyll resistance and transpiration of conditioned and non-conditioned tillers were equal. These data indicate an improvement in the drought tolerance of tall fescue and switchgrass plants, emphasize the importance of knowing the previous water stress history of the plants in moisture deficiency experiments, and help to choose proper irrigation management for switchgrass and tall fescue.
Aronson, L. J., Gold, A. J., Hull, R. J. (1987): Cool-season turfgrass responses to drought stress. Crop Science, 27, 1261-1266.
Beadle, C. L., Stevenson, K. R., Neumann, H. H., Thurtell, G. W., King, K. M. (1973): Diffusive resistance, transpiration, and photosynthesis in single leaves of corn and sorghum in relation to leaf water potential. Can. J. Plant Sci., 53, 537-544.
Stout, W. L., Jung, G. A., Shaffer, J. A., Estepp, R. (1986): Soil water conditions and yield of tall fescue, switchgrass, and Caucasian bluestem in the Appalachian Northeast. J. Soil and Water Cons., 41, 184-186.
Jones, M. B., Leafe, E. L., Stiles, W. (1980): Water stress in field-grown perennial ryegrass. II. Its effect on leaf water status, stomatal resistance and leaf morphology. Ann. Appl. Biol., 96, 103-110.
Jones, M. M., Rawson, H. M. (1979): Influence of rate of development of leaf water deficits upon photosynthesis, leaf conductance, water use efficiency, and osmotic potential in sorghum. Physiol. Plant., 45, 103-111.
Nyakas, A. (1997): Comparative anatomy of leaves between C3 and C4 grasses in Hungary. First International Seminar on Soil, Plant and Environment Relationships. Debrecen Agricultural University. 1, 261-269.
, , .
Comparative anatomy of leaves between C3 and C4 grasses in Hungary1261269)| false