Photosynthesis response of sunlit and shade pepper (Capsicum annuum) leaves at different positions in the canopy under two water regimes.
1994
Alvino A. | Centritto M. | De Lorenzi F.
Pepper plants were grown in lysimeters under 2 different water regimes: the control regime (well-watered (W) treatment) was irrigated whenever the accumulated 'A' pan evaporation reached 4 cm, whereas the water-stressed (S) treatment was watered whenever the predawn leaf water potential fell below -1 MPa. Control plants maintained predawn leaf water potential at -0.3 MPa, but S plants reached values lower than -1.2 MPa. Midday leaf water potentials were about twice as low in the S plants as in the controls. Water stress reduced LAI during the period of crop growth, and dry matter production at harvest. Stressed apical leaves appeared to reduce stress by changing their inclination. The CER values of the S treatment were significantly lower than those of the W treatment in apical and middle leaves, whereas the CER of basal leaves did not differ in either treatments. In the S treatment, reduction in the CER values of sunlit apical leaves was more evident in the afternoon than at midday or early in the morning, whereas basal leaves were less affected by water than basal stress leaves if sunlit, and negligibly in shaded conditions.
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