Articles
Water relations of asparagus crop under different water supply and implications for plant-based irrigation scheduling
Article number
1150_54
Pages
385 – 390
Language
English
Abstract
Irrigation plays a major role in the production of herbaceous crops, since they are highly sensitive to water shortage.
Methods for irrigation scheduling using indirect measures of plant water demand (e.g., soil matric potential) result in well-known disadvantages (e.g., imprecise since not based on the actual plant demand, high leachate risk in sandy soils), whereas irrigation scheduling using direct measures of plant water demand (e.g., predawn leaf water potential (ψPD)) might be more promising.
Therefore, we aimed at developing a ψPD-based irrigation scheduling for asparagus as a model crop.
First, we investigated the plants’ responses to water stress and, second, identified stress thresholds related to ψPD. In a field trial in Geisenheim, Germany, ‘Gijnlim’ asparagus was grown in irrigated and non-irrigated plots (3 replications, randomized block design). Irrigated plots were watered, if soil tension was below -20 kPa.
Parameters of gas exchange, plant growth, spear yield and osmotic adjustment (OA) were analysed with respect to the applied water amount and ψPD. As expected, lack of irrigation reduced shoot growth, yield and ψPD. Parameters of OA, turgor loss point, osmotic potential and modulus of elasticity, did not change.
Thus, OA did not occur.
However, stomatal conductivity and assimilation rate were significantly reduced for ψPD below -0.15 MPa, when ψPD-classes ranging from -0.10 to -0.15, -0.15 to -0.20 and <-0.2 MPa, respectively, were compared.
This implies that ψPD-thresholds of herbaceous species lie far above of those of woody species already used in practice.
Thus, herbaceous crops may challenge the irrigation management using ψPD as irrigation signal.
Methods for irrigation scheduling using indirect measures of plant water demand (e.g., soil matric potential) result in well-known disadvantages (e.g., imprecise since not based on the actual plant demand, high leachate risk in sandy soils), whereas irrigation scheduling using direct measures of plant water demand (e.g., predawn leaf water potential (ψPD)) might be more promising.
Therefore, we aimed at developing a ψPD-based irrigation scheduling for asparagus as a model crop.
First, we investigated the plants’ responses to water stress and, second, identified stress thresholds related to ψPD. In a field trial in Geisenheim, Germany, ‘Gijnlim’ asparagus was grown in irrigated and non-irrigated plots (3 replications, randomized block design). Irrigated plots were watered, if soil tension was below -20 kPa.
Parameters of gas exchange, plant growth, spear yield and osmotic adjustment (OA) were analysed with respect to the applied water amount and ψPD. As expected, lack of irrigation reduced shoot growth, yield and ψPD. Parameters of OA, turgor loss point, osmotic potential and modulus of elasticity, did not change.
Thus, OA did not occur.
However, stomatal conductivity and assimilation rate were significantly reduced for ψPD below -0.15 MPa, when ψPD-classes ranging from -0.10 to -0.15, -0.15 to -0.20 and <-0.2 MPa, respectively, were compared.
This implies that ψPD-thresholds of herbaceous species lie far above of those of woody species already used in practice.
Thus, herbaceous crops may challenge the irrigation management using ψPD as irrigation signal.
Authors
J. Zinkernagel, K. Kahlen
Keywords
Asparagus officinalis L., gas exchange, osmotic adjustment, plant-based irrigation management, predawn water potential, stress threshold
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