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Scanning electron microscope examination of the morphology of adaxial and abaxial leaf surfaces of salt spray-tolerant and normal plants of Agrostis stolonifera L., Dactylis glomerata L. and Holcus lanatus L. was carried out. Differences were found in degree and types of waxiness of epidermal cells, number and size of macro-hairs and prickles, epidermal cell lengths and extent to which stomata were sunken. These differences were consistent with a reduction of the wettability, and hence salt spray damage, to adaxial leaf surfaces. Abaxial leaf surface differences were much less pronounced. [ABSTRACT FROM AUTHOR]

Tolerance to sodium chloride in solution culture and its genetic basis has been assessed for populations of Festuca rubra L., Holcus lanatus L., Agrostis stolonifera L., and Dactylis glomerata L. from salt marsh, spray zone, and inland habitats. Two populations of F. rubra from salt marshes and one population of A. stolonifera from a spray zone showed significant NaC1 tolerance. However, in the main, responses of populations to increasing NaCl in the rooting medium showed little relationship with electrical conductivity or Na content of the soil. Narrow-sense heritability estimates were high for all populations, except for one F. rubra population from a salt marsh and the population of A. stolonifera from a spray zone. Broad-sense heritabilities were high for all populations suggesting high genetic components for variation in NaCl tolerance. [ABSTRACT FROM AUTHOR]

Leaf anatomy, rates of photosynthesis, leaf N, chlorophyll, RuBP carboxylase and nitrate reductase were studied on the indigenous Agrostis magellanica Lam. and the invasive alien Agrostis stolonifera L. on Marion Island (46° 54' S, 37° 45' E). Leaves of A. magellanica were more deeply ridged, thicker and more sclerophyllus than those of A. stolonifera. Mesophyll cells of A. magellanica were larger but the number of cells per unit leaf area and the total area of chloroplast per unit leaf area were the same for the two species. Maximum CO2 assimilation rates for the two species did not differ (mean maxima of 9.5 and 9 μmol CO2 m-2 s-1 for A. magellanica and A. stolonifera respectively). At low photon flux densities, A. stolonifera showed a greater response of CO2 assimilation to photon flux density. A. magellanica exhibited temperature-dependent photoinhibition. Leaf N, chlorophyll and RuBP carboxylase on a fresh or dry weight basis were higher in A. stolonifera but on a leaf area basis there was little difference between the species. The competitive ability of A. stolonifera on Marion Island may be related to its response to low photon flux densities or to its carbon allocation patterns (less sclerophyllous tissue means that a greater leaf area may be produced per unit carbon fixed). The lack of support tissue may limit it to sites partly sheltered from frequent gale force winds. [ABSTRACT FROM AUTHOR]

Two populations of Agrostis stolonifera and seven populations of Festuca rubra from salt marsh and inland habitats were grown on a free draining soil and at two levels of soil waterlogging. The growth of A. stolonifera was stimulated by soil waterlogging while that of F. rubra was depressed. There was no difference between the two populations of A. stolonifera in growth response to waterlogging but the inland population had a greater Fe concentration in the shoots when grown on waterlogged soil than the salt marsh population. In F. rubra the yield of the salt marsh populations was generally less depressed by soil waterlogging than that of populations from free draining soils; the salt marsh populations also had lower concentrations of Fe and Mn in the shoot on the continuously waterlogged soil than the inland populations. It is concluded that the evolution of a degree of waterlogging tolerance has occurred in the salt marsh populations of F. rubra in response to the periodic flooding by sea water in their native habitats. [ABSTRACT FROM AUTHOR]

Nitrate reductase activity (NRA) was assessed at several moments within the day during the early stages of establishment of tiller generated plants and seedling swards of Agrostis tenuis and A. stolonifera grown at different temperatures and levels of nitrate supply. Agrostis tennis consistently exhibited higher NRA values than A. stolonifera at initial developmental stages or low nitrate availability. The reverse situation was found to occur at high nitrate availability or in longer established plants and seedling swards. This emphasizes the difficulties in establishing consistent differences between species in NRA. Both species showed increased NRA with increased nitrate availability, increased night temperature or decreased day temperature. Agrostis stolonifera increased its NRA to a greater extent than A. tenuis as nitrate availability increased, The importance of daily and developmental variation in NRA in establishing differences between these species is discussed. [ABSTRACT FROM AUTHOR]

The tolerance to sodium chloride of clones of Agrostis stolonifera from salt marsh, spray zone, and inland habitats was measured in water cultures by a rooting technique and by growth analysis. The order of tolerance was found to be: salt marsh > spray zone > inland. The two methods of measurement of tolerance were found to show good agreement. Salt marsh plants were found to be more resistant to low dissolved oxygen concentrations in the culture solution than plants from the spray zone and inland habitats. With polyethylene glycol 6000 in culture solution, the pattern of resistance to osmotic stress in the absence of sodium chloride was similar to the pattern of resistance to salt. [ABSTRACT FROM AUTHOR]

Properties of the leaf surface associated with wettability were studied in ecotypes of Agrosti stolonifera from salt marsh, spray zone and inland habitats. The maritime ecotypes retained much less salt than the inland ecotype after immersion in salt water. Retention of salt after spraying was highest by leaves of the inland ecotype and least by those of the spray zone ecotype. Differences in retention of salt can be correlated with differences in wettability (indicated by measurement of advancing contact angle) and these differences are, in turn, related to differences in the structure and distribution of extracuticular waxes on the surfaces of leaves of the ecotypes. The differences are considered to be adaptations to the environments in which the ecotypes grow. [ABSTRACT FROM AUTHOR]

Zinc and copper uptake by Agrostis stolonifera, tolerant to both zinc and copper, showed that different zinc levels had no effect on copper uptake and, conversely, copper had no effect on zinc uptake. There was, however, a strong interaction in the toxic effects of zinc and copper as measured by root elongation. The mechanisms of zinc and copper tolerance are therefore independent even when they act in the same individual. [ABSTRACT FROM AUTHOR]

The uptake of copper by non-tolerant and tolerant clones of Agrostis stolonifera has been studied. In both clones the roots accumulated more copper than the leaves and the roots of the tolerant clone accumulated more copper than the non-tolerant one. When supplied at concentrations above 10 μM in culture solutions copper moved up into the leaves of the non-tolerant clone more readily than the tolerant one. Uptake of oxygen by roots was only affected when they were pretreated with copper, the non-tolerant ones being more sensitive to inhibition than tolerant ones. Over the concentration range tested copper had no effect upon l-malate-dehydrogenase (MDH) activity in root extracts of either clone. Extracts prepared from non-tolerant roots pretreated with copper were found to contain less MDH activity than those prepared from tolerant ones. It is suggested that this was due to an inhibition of protein synthesis in the roots of the non-tolerant clone, which did not occur in the tolerant one. [ABSTRACT FROM AUTHOR]

Epichloe typhina forms an intercellular systemic mycelium within its host, Agrostis stolonifera, and a stroma (upon which conidia and perithecia are produced) at the junction of the lamina and sheath of the flag leaf where association between the stroma and vascular tissue of the host is close. There is movement of labelled photosynthate to the stroma from other parts of the shoot. Movement through the systemic mycelium appears to be slight and most probably occurs through the host vascular tissue with subsequent uptake of photosynthate by the stroma. The principal carbohydrate acquired from the host is sucrose, and there is concomitant transformation to mannitol and trehalose by the fungus. [ABSTRACT FROM AUTHOR]