Showing papers on "Polygonum published in 1989"

Seedling Growth, Physiology, and Survivorship in a Subalpine, Volcanic Environment

Abstract: The relationship of seedling survivorship to specific physiological or mor- phological traits is usually only inferred in demographic studies. We compared seedling survivorship, growth, morphology, and water relations of two subalpine herbs (Eriogonum pyrolifolium and Polygonum newberryi) on Mount St. Helens in order to examine the relationship between population and functional biology more directly. Survivorship of two cohorts of seedlings (1982 and 1983) was followed through 4 and 3 yr, respectively. Seedling growth was measured in two substrate types (pre-eruption soil and 1980 deposited tephra) and under different levels of nutrients and water under controlled environmental conditions. Water relations parameters of the two species were determined in conjunction with the laboratory growth experiment. The 1982 cohort of Eriogonum had a significantly higher rate of survival than did that of Polygonum over four growing seasons, while the 1983 cohort did not differ in survival over three growing seasons. Survival rates were closely related to the amount of rainfall, with Eriogonum having significantly higher survival during dry periods than Polygonum. Growth of both species was greater in pre-eruption soil than in 1980 deposited tephra; the difference was much more pronounced in Polygonum. Growth of Eriogonum seedlings was also less sensitive to lower nutrient and water availability in the laboratory experiment than growth of Polygonum. Eriogonum had lower osmotic potentials, higher stomatal conductance, greater fine root biomass, and lower intrinsic growth rate than did Polygonum. These appear to be important characteristics contributing to greater stress tolerance and higher seedling survivorship in Eriogonum.

Weed control in winter wheat (Triticum aestivum) with chlorsulfuron and CGA 131036 and Comparison of modes of action.

Abstract: In field experiments, chlorsulfuron and CGA 131036 did not injure winter wheat. Both herbicides applied postemergence at 9 and 10 g ai/ha completely controlled flixweed. CGA 131036 controlled cutleaf eveningpnnmrose 81%, and chlorsulfuron controlled 91%. At similar rates, CGA 131036 was also less effective than chlorsulfuron on henbit and Italian ryegrass. Both controlled wild buckwheat 77% when applied postemergence at 18 g/ha. Neither of the sulfonylurea herbicides controlled prostrate spurge or woolly croton as effectively as 2,4-D. In a bean root bioassay, root growth inhibition by both herbicides was partially alleviated by adding isoleucine and valine. Nomenclature: Chlorsulfuron, 2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl) amino]carbonyl]benzenesulfonamide; CGA 131036, N-(6-methoxy-4-methyl-1,3,5-triazin-2-yl-aminocarbonyl)2-(2-chloroethoxy)-benzenesulfonamide; 2,4-D, (2,4-dichlorophenoxy)acetic acid; bean, Phaseolus vulgaris L.; winter wheat, Triticum aestivum L.; flixweed, Descurainia sophia (L.)Webb. ex Prantl #3 DESSO; cutleaf eveningprimrose, Oenothera laciniata Hill # OEOLA; henbit, Lamium amplexicaule L. # LAMAM; wild buckwheat, Polygonum convolvulus L. # POLCO; Italian ryegrass, Lolium multiflorum Lam. # LOLMU; woolly croton, Croton capitatus Michx. # CVNCP; prostrate spurge, Euphorbia humistrata Engelm. ex Gray # EPHHT. Additional index words: Phaseolus vulgaris, Descurainia sophia, Oenothera laciniata, Lamium amplexicaule, Polygonum convolvulus, Lolium multiflorum, Croton capitatus, Euphorbia humistrata, bioassay, LAMAM, DESSO, OEOLA, POLCO, LOLMU, CVNCP, EPHHT.

Hybridization between Polygonum mite Schrank, P. minus Huds. and P. hydropiper L. in Northern Ireland with comments on their distinction

Abstract: ABSTRACf 265 Polygonum mite Schrank, P. minus Huds. aDd P. hydropiper L., in Polygonum sect. Persicaria (Miller) DC. occur together around Lough Neagh, Northern Ireland. Initial observations of these species had suggested the presence of intermediate plants of possible hybrid origin . Populations from two sites at the Lough were examined for hybridity using multivariate analyses, and by measurement of pollen fertility. Most plants could be assigned to one of the three species, but a few were almost certainly hybrids between P. mite and P. minus (= P. x wilmsii G. Beck) . P. hydropiper did not appear to hybridize with the other species, although P. mite and P. hydropiper may approach each other in their vegetative morphology. The characters which best distinguish the three species are described and discussed .

Polygonum papillosum (Polygonaceae), a new species from Central Greece

Abstract: Polygonum papillosum, a woody species of Polygonum sect. Polygonum from serpentine soils in Central Greece, is described as a species new to science and illustrated. It is related to the Anatolian P. setosum, but differs in leaves with very dense and prominent, papillose veins, strongly splitting ochreas and numerous elongated vegetative shoots