Effects of water stress on gas exchange of field grown Zea mays L. in Southern Italy: an analysis at canopy and leaf level

Abstract

Zea mays is cultivated in the Mediterranean regions where summer drought may lead to photoinhibition\ud when irrigation is not available. In this work the response of maize to water stress was evaluated by gas exchange measurements at the canopy and leaf level. Leaf gas exchange was assessed before, during and after water stress, while canopy turbulent fluxes of mass and energy were performed on a continuous basis. In the early growth period, a linear increment of net ecosystem photosynthetic rate\ud (PNE) to incoming of photosynthetic photon flux density (PPFD) was found and net leaf photosynthetic rate (PNL) showed the tendency to saturate under high irradiance. During water stress, the relationship between PNE and PPFD became curvilinear and both PNE and PNL saturated in a range between 1,000 and 1,500 lmol (photons) m–2 s–1. Leaf water potential (wl) dropped from –1.50 to –1.88 MPa during water stress, indicating that leaf and canopy gas exchanges were limited by stomatal conductance. With the restoration of irrigation, PNE, PNL and wl showed a recovery, and PNE and PNL reached the highest values of whole study period. Leaf area index (LAI) reached a value of 3.0 m2 m–2. The relationship between PNE and PPFD remained curvilinear and PNE values were lower than those of a typical well-irrigated maize crop. The recovery in PNE and PNL after stress, and wl values during stress indicate that\ud the photosynthetic apparatus was not damaged while soil moisture stress after-effects resulted in a sub-optimal LAI values, which in turn depressed PNE

Growth and gas exchange response to water shortage of a maize crop on different soil types

“…1c,5) during the dry spell allow to postulate very low SWC values at layers accessible for the roots of maize in the sandy area, due to the lower capacity of the SS to retain water. SWC values lower than 0.20 m 3 m -3 at 0.50 m depth in the clay area of the field were reported in a previous study carried out during summer 2004 at the same experimental site during a long, dry spell (Vitale et al 2007).…”

“…When SWC was higher than 20%, net photosynthetic rates (A N ) measured on plants grown on either CS or SS, were in a range commonly found for well-watered maize (Leakey et al 2006), indicating the absence of physiological limitations; moreover, the trend of net ecosystem CO 2 exchange at 1,500 lmol (photons) m -2 s -1 (NEE 1,500 ) during the vegetative stage, and the linear increase in NEE to incoming PPFD provide evidence of an elevated light use efficiency in photosynthesis (Suyker et al 2004;Vitale et al 2007). The dry spell between 76 and 88 DAS, when SWC dropped below 14% in both soil types, limited leaf CO 2 uptake both in CS and in SS plants, and in turn affected the CO 2 uptake by the canopy.…”

Root system traits and its relationship with photosynthesis and productivity in four maize genotypes under drought

“…One of the earliest responses to WD is stomatal closure, which limits the leaf gas exchange and therefore productivity (Mutava et al 2011). Assessing the Ψ md at the end of the drought imposition period in maize genotypes grown under WD, Vitale et al (2007) and Souza et al (2013) found a reduced Ψ md compared to their respective controls under FC. Souza et al (2013) also observed a differential maintenance of water status under WD, depending on the degree of tolerance of the genotype to WD, with higher values in tolerant genotypes than in sensitive ones.…”

The response of ecosystem carbon fluxes to LAI and environmental drivers in a maize crop grown in two contrasting seasons

“…Cropland represents about 12 % of earth's surface (Wood et al 2000) and received increasing scientific attention in the last decades for its potential carbon sequestration role (Lal et al 1998;Vleeshouwers and Verhagen 2002;Suyker et al 2004;Verma et al 2005;Vitale et al 2007Vitale et al , 2009Vitale et al , 2011aJans et al 2010). However, it is often difficult to predict C sequestration of arable land due to the role played by management practices, which impact on both the amount of carbon fixed by plants and on that released by organic matter decomposition .…”