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Effects of Water and Nitrogen Supply on Water Use Efficiency and Carbon Isotope Discrimination in Edible Canna ( Canna edulis Ker‐Gawler)
Author(s) -
Brück H.,
Jureit C.,
Hermann M.,
Schulz A.,
Sattelmacher B.
Publication year - 2001
Publication title -
plant biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 1435-8603
DOI - 10.1055/s-2001-16450
Subject(s) - canna , biology , water use efficiency , nitrogen , shoot , agronomy , horticulture , dry matter , botany , irrigation , chemistry , biochemistry , organic chemistry , starch
Transpirational water use efficiency (WUE) is affected by nutrient and water supply, but relatively little is known about the response of Andean root and tuber crops, such as edible canna ( Canna edulis Ker‐Gawler). Two Canna edulis genotypes were studied in semi‐controlled greenhouse experiments at the International Potato Centre (CIP) near Quito, Ecuador. Under conditions of low water supply, shoot dry matter (DM), leaf area and specific leaf nitrogen (SLN) all decreased, while WUE was higher and carbon isotope discrimination (Δ) decreased. The large water‐storing hypodermal cells characteristic of this plant's leaf morphology shrank, concertina‐like, the leaves became thinner, and the specific leaf area increased significantly (from 26 m ‐2 kg ‐1 to 43 m ‐2 kg ‐1 ). In a second experiment, plants were grown with three different levels of nitrogen supply: from low to high N supply, shoot DM increased significantly (from 16 to 37 g), along with leaf area and SLN. At the lowest level of nitrogen supply (N0), WUE was significantly lower and Δ increased. As expected, the linear correlation between Δ and WUE was negative, but variation in Δ could only explain 49 % of the variation in WUE. If, in addition to Δ, measured root fraction (RF) and estimated values of leaf‐to‐air vapour pressure deficit (Δe) and respiratory and unproductive carbon loss were used to calculate WUE, the correlation between measured and calculated WUE was substantially improved, except for the water stress treatment. It is considered that, for root and tuber crops, RF and Δe are the major variables when Δ of single leaves is to be used for up‐scaling to plant WUE.