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Andarzian B.,Agricultural and Natural Resources Research Institute of Khuzestan | Bannayan M.,Ferdowsi University of Mashhad | Steduto P.,Water Resources | Mazraeh H.,Agricultural and Natural Resources Research Institute of Khuzestan | And 3 more authors.
Agricultural Water Management | Year: 2011

Accurate crop development models are important tools in evaluating the effects of water deficits on crop yield or productivity and predicting yields to optimize irrigation under limited available water for enhanced sustainability and profitable production. Food and Agricultural Organization (FAO) of United Nations addresses this need by providing a yield response to water simulation model (AquaCrop) with limited sophistication. The objectives of this study were to evaluate the AquaCrop model for its ability to simulate wheat (Triticum aestivum L.) performance under full and deficit water conditions in a hot dry environment in south of Iran, to study the effect of different scenarios of irrigation (crop growth stages and depth of water applied) on wheat yield. The AquaCrop model was evaluated with experimental data collected during the three field experiments conducted in Ahvaz. The AquaCrop model was able to accurately simulate soil water content of root zone, crop biomass and grain yield, with normalized root mean square error (RMSE) less than 10%. The analysis of irrigation scenarios showed that the highest grain yield could be obtained by applying four irrigations (200 mm) at sowing, tillering, stem elongation and flowering or grain filing stages for wet years, four irrigations (200 mm) at sowing, stem elongation and flowering stages for normal years and six irrigations (300 mm) at sowing, emergence, tillering, stem elongation, flowering and grain filing stages for dry years. The least amount of irrigation water to provide enough water to response to evaporative demand of environment and to obtain high WUE for wet, normal and dry years were 100, 200 and 250 mm, respectively. © 2011 Elsevier B.V.

Sayad E.,Behbahan University of Technology | Hosseini S.M.,Tarbiat Modares University | Hosseini V.,University of Kurdistan | Salehe-Shooshtari M.-H.,Agricultural and Natural Resources Research Institute of Khuzestan
Journal of Forest Science | Year: 2012

Soil communities exert strong influences on the processing of organic matter and nutrients. Plantations of trees, especially of nitrogen fixing ones, may affect the soil macrofauna through litter quality and quantity. This study was conducted in a randomized block design with three blocks consisting of Populus euphratica, Eucalyptus camaldulensis, Eucalyptus microtheca, Acacia farnesiana, Acacia salicina, Acacia saligna, Acacia stenophylla and Dalbergia sissoo monoculture plantations that were established in 1992. Soils and soil macrofauna were sampled in November 2006. Leaf litterfall was collected from November 2006 to November 2007 at bi-weekly intervals. Macroinvertebrate abundance and biomass were consistently higher in A. salicina plantations than in the others, whereas they were lowest in E. camaldulensis. Tree species and nitrogen fixing trees significantly influenced the soil macrofauna richness. The results suggest that the earthworm distribution is regulated by leaf litter quality (Ca, C and N) whereas the macrofauna richness is regulated by leaf litter mass, soil organic carbon and leaf litter Mg. Totally, it was revealed that the tree species clearly affected macrofauna whereas nitrogen fixation did not.

Sayad E.,Razi University | Hosseini V.,University of Kurdistan | Gholami S.,Razi University | Salehe-Shooshtari M.H.,Agricultural and Natural Resources Research Institute of Khuzestan
Trees - Structure and Function | Year: 2015

Key message: This study shows that functional grouping of the species based on nitrogen fixing ability along with initial leaf litter C/P, C/N, P and N could help us predicting leaf litter decomposition rate.Abstract: Grouping species into functional groups is a good approach to understanding exotic plants impacts on ecosystem functioning in their new environment. One key plant trait that has large ecosystem-level consequences is the ability of plants to fix atmospheric nitrogen into plant available forms. Most previous studies have reported faster leaf litter decomposition rates of nitrogen fixing than non-nitrogen-fixing species, supporting the separation of these as functional groups. Here, we present a multispecies monitoring of litter decomposability of seven tree species in a 1 year decomposition experiment in outdoor litter bed common garden experiment in river floodplain in South Western Iran. We tested within- and between-functional-groups for rates of leaf litter decomposition and nutrient dynamics. Our results highlight that nitrogen-fixing trees and non-nitrogen-fixing trees can be distinguished based on specific leaf area and leaf litter traits. The interesting results were that the leaf litter decomposition rates of the two functional groups were related to different initial leaf litter traits. Leaf litter decomposition rates of nitrogen-fixing trees were related to initial leaf litter C/P, C/N, N, P and Ca, while leaf litter decomposition rates of non-nitrogen-fixing trees were only related to initial leaf litter Ca. Whereas specific leaf area was the best predictor of leaf litter decomposition rates among all the species. Therefore, our results revealed that both initial leaf litter traits and functional groups were predicting leaf litter decomposition rates. © 2015 Springer-Verlag Berlin Heidelberg

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