Soil water depletion in irrigated mature pecans under contrasting soil textures for arid Southern New Mexico
Irrigation Science (Impact Factor: 2.06). 01/2013; 31(1):69-85. DOI: 10.1007/s00271-011-0293-1
Relationship between plant water stress and soil water depletion (SWD) is not investigated thoroughly for irrigated pecans of southern New Mexico. In this study, transient soil water contents, rootzone SWD, and midday stem water potential (SWP) were monitored in mature pecan orchards in sandy loam (Site 1) and silty clay loam (Site 2) soils near Las Cruces, New Mexico. Corresponding to transient variations of soil water content at different depths, daily SWD varied with soil depth but not spatially. The SWD within the rootzone (0–80 cm) was higher in the shallow depths (0–40 cm) where root length density (RLD) was also higher than in the deeper depths (40–80 cm). The SWD at Site 1 was higher compared to Site 2 due to the higher clay content of the latter. The SWD patterns at outside the tree driplines were similar to those under-canopy locations because of similar RLD at the shallow depths. At both pecan orchards, differences in SWP at 2.5, 4.5, and 7.6 m tree heights were evident particularly 10–14 days after irrigation. This was due to the stress caused by decreasing soil water contents at different depths, which were generally significantly correlated with SWP. Midday air temperature was as useful as midday atmospheric vapor pressure deficit for interpreting SWP. Combined influence of soil water content (0–40 cm) and air temperature on midday SWP was significant at both orchards, which can be used as an adjunct for the clear interpretation of SWP to help refine irrigation scheduling.
- [Show abstract] [Hide abstract]
ABSTRACT: Quantitative information about the spatial and temporal patterns of compensatory root water uptake (RWU) in flood-irrigated pecan orchard is limited. We evaluated spatio-temporal compensated and uncompensated RWU patterns of mature pecan tree in a silty clay loam orchard using the HYDRUS (2D/3D) model. HYDRUS (2D/3D) simulations, which agreed well with measured water contents and temperatures at different soil depths and horizontal distances from the tree trunk, suggested that while both compensated and uncompensated RWU varied with soil depth they did not do so laterally because of similar spatial vertical distributions of root length density (RLD) for the under-canopy and the tree canopy dripline locations. Considering compensated RWU resulted in an increase in actual transpiration by 8%, and a decrease in evaporation and drainage by 5% and 50%, respectively, during a growing season. Simulated transpiration and relative transpiration (a ratio between actual and potential transpiration) values were correlated with measured transpiration and plant-based water stress indicators (stem and leaf water potentials), respectively. Overall, our results of the spatio-temporal compensatory RWU provide support to use HYDRUS (2D/3D) as a tool for managing efficient water use of pecan. (C) 2013 American Society of Civil Engineers.Journal of Irrigation and Drainage Engineering 08/2013; 139(8):599-611. DOI:10.1061/(ASCE)IR.1943-4774.0000611 · 0.97 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Salinity responses and salinity-related suppression of budbreak of dripirrigated pecan [Carya illinoinensis (Wangenh.) K. Koch] seedlings under different irrigation water salinity (ECIRR) levels were investigated in the pot-in-pot system. The 1-year-old pecan seedlings of rootstock 'Riverside' grafted with 'Western Schley' scions were transplanted in pots filled with sandy loam soil and grown for 2 years under the same amount of irrigation water but four irrigation ECIRR treatment levels consisting of 1.4 dS·m-1 (control), and three qualities of irrigation water obtained by using a solution of calcium chloride (CaCl2) and sodium chloride (NaCl) in a ratio of 2:1 (by weight) to reach the ECIRR levels of 3.5, 5.5, and 7.5 dS·m-1, respectively. The leachate electrical conductivity (ECd) was highly correlated with soil salinity (EC1:1) and was significantly higher when the irrigation ECIRR treatment levels increased from 1.4 (control) to 7.5 dS·m-1. However, both ECd and EC1:1 remained nearly constant within the same irrigation ECIRR treatment level during both years. Increasing salinity in irrigation water, particularly the ECIRR levels of 5.5 and 7.5 dS·m-1, showed significantly low seedling height and stem diameter growth and delayed or even inhibited budbreak in the seedlings. The EC1:1 that inhibited seedling heights, stem diameters, and budbreak was somewhere between 0.89 and 2.71 dS·m-1 (or ECIRR between 1.4 and 3.5 dS·m-1 and ECd between 2.10 and 4.86 dS·m-1), providing that soil water content was not a limiting factor in the root zone and irrigation water was uniformly distributed in the confined root zone to obtain uniform salt leaching. The visual symptoms of leaf scorch for irrigation ECIRR levels of 3.5, 5.5, and 7.5 dS·m-1 also indicated that somewhere between 0.89 and 2.71 dS·m-1 of the EC1:1, salt injury started to occur. Increasing salinity in irrigation water significantly increased chloride (Cl-) accumulation but reduced nitrogen (N) content in the scorched leaves, particularly under the irrigation ECIRR levels of 5.5 and 7.5 dS·m-1. Leaf scorch symptoms in pecan seedlings were likely associated with Cl-toxicity. No pecan seedlings under the irrigation ECIRR treatment levels of 5.5 and 7.5 dS·m-1 survived to the end of the 2-year growing period. Thus, threshold EC1:1 was somewhere between 0.89 and 2.71 dS·m-1 beyond which plant injury increases with increasing EC1:1 threatening the survival of pecan seedlings.HortScience: a publication of the American Society for Horticultural Science 12/2013; 48(12):1548-1555. · 0.90 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Demand for New Mexico’s limited water resources coupled with periodic drought has increased the necessity for tree water status monitoring to guide irrigation scheduling of pecan (Carya illinoinensis) orchards. The objectives of this study were to assess the impact of water status developed during the flood irrigation dry-down cycles on photosynthesis (Pn), and gas exchange [stomatal conductance (gS) to H2O (gH2O), transpiration (E), and intercellular CO2 (ci)] and to establish values of midday stem water potential (Ψsmd) that are needed to maintain Pn and gas exchange of pecan. We conducted the study simultaneously on two southern New Mexico mature pecan orchards from 2011 through 2013. Flood irrigation as determined by grower practice was used on both orchards and Pn, gH2O, E, and ci were assessed at Ψsmd of –0.4 to –2.0 MPa. Photosynthesis and gas exchange were higher in pecan trees shortly after irrigation than trees exhibiting water deficit near the end of a flood irrigation dry-down cycle. The decline in Pn was markedly noticeable when Ψsmd dropped below –0.9 MPa. We attributed the reduction in Pn mostly to stomatal limitation. The decline in Pn and gH2O exceeded 50% when Ψsmd ranged from –1.5 to –2.0 MPa. For those reasons, we recommended that pecan orchards be maintained at Ψsmd higher than –0.90 MPa to prevent significant reductions in carbon assimilation and gas exchange.Journal of the American Society for Horticultural Science. American Society for Horticultural Science 01/2014; 139(5):537-546. · 1.28 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.