Carbon Isotope Discrimination in Coffee Genotypes Grown under Limited Water Supply |
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Authors: | Meinzer F C Goldstein G Grantz D A |
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Institution: | Hawaiian Sugar Planters' Association, P. O. Box 1057, Aiea, Hawaii 96701. |
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Abstract: | Photosynthetic gas exchange, plant-water relations characteristics, and stable carbon isotope discrimination (Δ) were evaluated for five Coffea arabica L. genotypes growing under two soil moisture regimes in the field. The Δ of leaf tissue was strongly correlated (r = −0.95) with inherent water use efficiency (ratio of assimilation to stomatal conductance; A/g). The variation in inherent water use efficiency (WUE) among genotypes was 30% for plants irrigated weekly. The higher WUE exhibited by some of these plants resulted from reduced g rather than increased photosynthetic capacity at a given g. Withholding irrigation for 1 month caused Δ to decline substantially in expanding leaf tissue of all genotypes. A strong correlation (r = 0.92) was found between Δ and plant hydraulic efficiency estimated as the ratio of g to the diurnal range in leaf water potential (Ψl). The Δ values for plants irrigated weekly adequately predicted drought-induced changes in Δ (r = 0.99) and midday Ψl (r = 0.95). The results indicated that Δ might be used to evaluate several aspects of plant performance and response to specific environmental conditions, once suitable background physiological data have been gathered. |
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