Water relations and leaf growth rate of three Agropyron genotypes under water stress.

The effects of water stress on leaf water relations and growth are reported for three perennial tussock grass genotypes under glasshouse conditions. Studies were performed in genotypes El Palmar INTA and Selección Anguil of Agropyron scabrifolium (Döell) Parodi, and El Vizcachero of A. elongatum (Host) Beauv. Agropyron scabrifolium El Palmar INTA is native to a region with warm-temperate and humid climate without a dry season, and an average annual precipitation of 900 mm. Agropyron scabrifolium Selección Anguil comes from a region with a sub-humid, dry to semiarid climate and a mean annual precipitation of 600 mm. Agropyron elongatum is a widespread forage in semiarid Argentina with well-known water stress resistance. A mild water stress treatment was imposed slowly; plants reached a minimum pre-dawn leaf water potential of about -1.83 MPa by day 21 after watering was withheld. In all genotypes, water stress led to a reduction of leaf growth. There was a tendency for a greater epicuticular wax accumulation on water-stressed plants of A. scabrifolium Selección Anguil and A. elongatum than on those of A. scabrifolium El Palmar INTA. This may have contributed to obtain greater turgor pressures and relative water contents in the first two than in the later genotype. In turn, this may have contributed to determine smaller leaf growth rate reductions in A. scabrifolium Selección Anguil and A. elongatum than in A. scabrifolium El Palmar INTA under water stress. This study demonstrated variation in water stress resistance between genotypes in A. scabrifolium, and between A. scabrifolium Selección Anguil and A. elongatum versus A. scabrifolium El Palmar INTA, which was related to their differential responses in water relations.

Water relations and leaf growth rate of three Agropyron genotypes under water stress.

The effects of water stress on leaf water relations and growth are reported for three perennial tussock grass genotypes under glasshouse conditions. Studies were performed in genotypes El Palmar INTA and Selección Anguil of Agropyron scabrifolium (D÷ell) Parodi, and El Vizcachero of A. elongatum (Host) Beauv. Agropyron scabrifolium El Palmar INTA is native to a region with warm-temperate and humid climate without a dry season, and an average annual precipitation of 900 mm. Agropyron scabrifolium Selección Anguil comes from a region with a sub-humid, dry to semiarid climate and a mean annual precipitation of 600 mm. Agropyron elongatum is a widespread forage in semiarid Argentina with well-known water stress resistance. A mild water stress treatment was imposed slowly; plants reached a minimum pre-dawn leaf water potential of about -1.83 MPa by day 21 after watering was withheld. In all genotypes, water stress led to a reduction of leaf growth. There was a tendency for a greater epicuticular wax accumulation on water-stressed plants of A. scabrifolium Selección Anguil and A. elongatum than on those of A. scabrifolium El Palmar INTA. This may have contributed to obtain greater turgor pressures and relative water contents in the first two than in the later genotype. In turn, this may have contributed to determine smaller leaf growth rate reductions in A. scabrifolium Selección Anguil and A. elongatum than in A. scabrifolium El Palmar INTA under water stress. This study demonstrated variation in water stress resistance between genotypes in A. scabrifolium, and between A. scabrifolium Selección Anguil and A. elongatum versus A. scabrifolium El Palmar INTA, which was related to their differential responses in water relations.

Embryogenic cell suspensions from different explants and cultivars of Eragrostis curvula (Schrad. ) Nees

The aim of this work was the establishment of embryogenic calli and cell suspensions from different explants and cultivars of weeping lovegrass, Eragrostis curvula (Schrad.) Nees, to be used as targets for biolistic transformation. Calli were initiated from immature inflorescences, seeds, embryos, leaf bases and root tips. Modified MS medium (Murashige and Skoog, 1962) was used for calli induction and proliferation. Cell suspensions were established and maintained in AAF medium (Wang et al., 1993). Morphogenic calli, embryogenic cell suspensions of moderate growth rate--consisting mainly of compact proembryogenic cell clusters- and green plants were obtained from all the explants and cultivars assayed, except root tips. Both, explant and genotype were very important factors to be considered in order to obtain a morphogenic response and to establish cell suspensions from this grass. The statistical analysis detected interaction between both factors, explants and genotypes. Immature inflourescences were the best source of explant and Kromdraai was the cultivar that showed the best morphogenic response (expressed as the percentage of calli/explant and the percentage of calli with green spots--every green spot developed into green plants-) with inflourescences, embryos and leaf bases. For Morpa and Don Pablo embryos as explants were less responsive than seeds and leaf bases. There were no differences in leaf bases for all the three cultivars analysed.

Embryogenic cell suspensions from different explants and cultivars of Eragrostis curvula (Schrad. ) Nees

The aim of this work was the establishment of embryogenic calli and cell suspensions from different explants and cultivars of weeping lovegrass, Eragrostis curvula (Schrad.) Nees, to be used as targets for biolistic transformation. Calli were initiated from immature inflorescences, seeds, embryos, leaf bases and root tips. Modified MS medium (Murashige and Skoog, 1962) was used for calli induction and proliferation. Cell suspensions were established and maintained in AAF medium (Wang et al., 1993). Morphogenic calli, embryogenic cell suspensions of moderate growth rate--consisting mainly of compact proembryogenic cell clusters- and green plants were obtained from all the explants and cultivars assayed, except root tips. Both, explant and genotype were very important factors to be considered in order to obtain a morphogenic response and to establish cell suspensions from this grass. The statistical analysis detected interaction between both factors, explants and genotypes. Immature inflourescences were the best source of explant and Kromdraai was the cultivar that showed the best morphogenic response (expressed as the percentage of calli/explant and the percentage of calli with green spots--every green spot developed into green plants-) with inflourescences, embryos and leaf bases. For Morpa and Don Pablo embryos as explants were less responsive than seeds and leaf bases. There were no differences in leaf bases for all the three cultivars analysed.(AU)