Cooperative Research Centre

About: Cooperative Research Centre is a based out in . It is known for research contribution in the topics: Population & Sea ice. The organization has 7633 authors who have published 8607 publications receiving 429721 citations.

Hydrological persistence and the ecology of dryland rivers

Abstract: The flow regime of Cooper Creek, central Australia, is subject to a summer-monsoonal climate and aseasonal cycles associated with the El Nino–Southern Oscillation (ENSO). Analysis of a 48-year hydrograph indicates that floods tend to occur in clusters associated with La Nina episodes. The influence of ENSO is apparent in lagged correlations between discharge and values of the Southern Oscillation Index (SOI), and in measures of coherency derived from cross-spectrum analysis. Hydrological persistence is indicated by partial auto-correlations between floods in successive years. In a cluster of five floods over 1987–1991, cumulative effects were apparent in wetland habitat areas, in water temperature and transparency, and in the recruitment patterns of five fish species: Nematalosa erebi (Clupeidae), Hypseleotris klunzingeri (Gobiidae), Melanotaenia splendida tatei (Melanotaeniidae), Retropinna semoni (Retropinnidae) and Gambusia holbrooki (Poeciliidae). During serial floods, native fish appear to have a recruitment advantage over the exotic Gambusia. Hydrological persistence and its ecological correlates warrant consideration in research, planning and management, particularly in regard to the water resources of arid and semi-arid regions. Copyright © 2000 John Wiley & Sons, Ltd.

Characterizing soil salinity in irrigated agriculture using a remote sensing approach

Abstract: Managing salinity in irrigated agriculture is crucial for minimising its negative environmental impacts and for ensuring the long-term sustainability of irrigated agriculture. It demands establishing rapid monitoring systems that help develop sustainable management plans. Remote sensing offers several advantages over the conventional proximal methods to map and predict areas at salinity risk. This paper presents an integrated approach to characterize soil salinity using remotely-sensed data in the District Faisalabad, Punjab, Pakistan. The IRS-1B LISS-II digital data was acquired and analysed in combination with field data and topographical maps. Remotely-sensed data based salinity indices or band combinations were developed to monitor the occurrence pattern of salt-affected soils. Using supervised maximum likelihood classification, the images were classified into eight land use classes with an overall accuracy of around 90%. The classified images showed that 22.2% of the total area was under salt-affected soils in 1992. The occurrence pattern of salt-affected soils varied with positive and negative trends during 1992–1995 to a minimum of 10.6%. The delineation analysis into levels of saline soils revealed three types based on USDA classification ( USDA, 1954 ). The slightly saline, moderately saline and strongly saline soils during 1992 were in the order of 15%, 3%, and 1% respectively. The interactive behaviour of salinity and sodicity and their combinations showed that saline-sodic soils occurred predominantly ranging from 6.9% to 17.3% of the salt-affected soils. The shallow watertable was found to be of hazardous quality in 28% of the study area. The relationship between salt-affected soils, waterlogged soils and groundwater quality revealed that 60–70% of the salt-affected soils occurred in shallow watertable areas during 1992–1995. The reuse of poor quality groundwater for irrigation and the failure of tile drainage system in the area are likely to further increase the risk of salinisation in the Indus Basin of Pakistan.

Grape vine varieties Shiraz and Grenache differ in their stomatal response to VPD: apparent links with ABA physiology and gene expression in leaf tissue

Abstract: Two cultivars of Vitis vinifera L., namely Grenache and Shiraz, have been described as having near-isohydric and near-anisohydric responses respectively to soil water stress (Schultz, Plant Cell and Environment, 26, 1393-1405, 2003). Given that contrast in sensitivity to soil water, a question arises as to whether atmospheric moisture stress will elicit similar differences. The present study was undertaken to investigate this issue by comparing stomatal responses in these same two cultivars to contrasting vapour pressure deficit (VPD). Test material included field grape vines in the Barossa Valley and pot-grown vines under partial shade in Adelaide. Our experiments showed that the same isohydric/anisohydric distinction as described by Schultz (2003) is apparent in leaf responses to atmospheric moisture stress. In the more isohydric cultivar, Grenache, stomatal conductance is more responsive to changes in VPD. This heightened sensitivity (compared with Shiraz) appears to be associated with higher levels of abscisic acid (ABA) in Grenache xylem sap. Expression studies on the key genes in the ABA biosynthetic pathway indicate that regulation of the V.v.nced1 gene expression in leaf tissue, but not in the root tissues, is associated with the changes in the xylem sap ABA. Moreover, the two cultivars (Grenache and Shiraz) differed with respect to both scale and time course of those responses. We conclude that these two Vitis vinifera cultivars do indeed differ significantly in the way that they respond to potentially stressful atmospheric conditions, and that ABA physiology is a key process in these contrasting responses. An understanding of such mechanisms, including the relative importance of roots and shoots in determining vine response to abiotic stress, is highly relevant to irrigation scheduling, and to management of associated variation in vineyard productivity across diverse environments.