บทคัดย่องานวิจัย

หมวดหมู่ : ฐานข้อมูลงานวิจัย

Relationship between leaf water potential and gas exchange activity at different phenological stages and fruit loads in peach trees

Marsal, J. and Girona, J.

Journal of the American Society for Horticultural Science. Vol: 122 Issue: 3 Pages: 415-421.

1997

บทคัดย่อ

Relationship between leaf water potential and gas exchange activity at different phenological stages and fruit loads in peach trees.

Relationships between midday leaf water potential and predawn leaf water potential, stomatal conductance (gs), and net CO2 assimilation rate (A) were determined at different fruit growth stages and for 2 years with different fruit loads in a 'Sudanell' peach [Prunus persica (L) Batsch] plot subjected to two regulated deficit irrigation (RDI) strategies plus a control irrigation treatment. A postharvest RDI (PRDI) treatment was irrigated at 0.35 of the control after harvest. The second treatment (SPRDI) applied RDI during Stage II, the lag phase of the fruit growth curve, at 0.5 of the control and postharvest at 0.35 of the control. The control treatment and the PRDI and SPRDI when not receiving RDI were irrigated at 100% of a modified Penman crop water use calculation (ETo) in 1994, a full crop year, and 80% in 1995, a year of nearly zero crop. In 1995, with 80% of the 1994 irrigation rate and no crop, the midday leaf water potential was higher, probably because of the lower crop load, while predawn leaf water potential was lower, probably because less water was applied to the soil. The relationship of gs and A with midday leaf water potential during Stage II was steeper than during postharvest. Low midday leaf water potential was not indicative of a depression in gs and A in Stage III. Osmotic leaf water potential at turgor loss as derived from pressure-volume curves was more negative during Stage III and postharvest (about -2.9 MPa) than in Stage II (about -2.7 MPa). The midday leaf water potential measurements together with osmotic leaf water potential determinations seemed to be more useful to characterize peach tree water status than predawn leaf water potential under soil water deficits because of their better relationship to midday stomatal closure.