Abstract
Population structure and seed yield of a wild stand of Physaria mendocina (Brassicaceae). Implications for its development as an oilseed crop: Wild stands of the perennial forb Physaria mendocina (syn Lesquerella mendocina, Brassicaceae), are uncommon, small and inconspicuous. This species, native to the Monte desert, is being evaluated as a new oil-seed crop for arid lands. We evaluated a wild population in the Lihue Calel National Park (La Pampa, Argentina) for three years: 2000, 2001, and 2002. The aims of our study were: 1) to characterize the spatial distribution, density and size structure of this population, and 2) to analyze the relationship between population structure and individual plant seed-production. The relationship between population structure and productivity was evaluated using path analysis. We found an aggregated spatial distribution pattern, with patches of high and low density. The proportion of larger size individuals increased in low density patches, respect to those in with high density in which prevailed smaller individuals. Smaller plants had less biomass accumulation and seed production, and had a greater below ground allocation, in relation to larger plants. Individual total biomass was the main determinant of the observed variation in seed-yield in relations to plant size, while harvest index was very stable across the range of plant diameter. The understanding of functional mechanics of seed production should aid in the conservation of wild stands, and in the domestication of this perennial species.
Highlights
Population structure and seed yield of a wild stand of Physaria mendocina (Brassicaceae)
Del conjunto de 100 especies descritas en este género, Physaria fendleri, P. gracilis, P. angustifolia, P. mendocina y P. pinetorum han sido elegidas por su potencial agronómico y su tolerancia a la sequía para la introducción en programas de domesticación y selección para zonas áridas
Para evaluar la estructura por tamaños, los individuos dentro de cada parcela se clasificaron en cuatro clases de diámetro: ≤2, de 2 a 4, de 4 a 6, y >6 cm
Summary
Estructura y productividad de una población silvestre de Physaria mendocina (Brassicaceae). Implicancias para su desarrollo como cultivo oleaginoso. Es una hierba perenne nativa del Monte en Argentina, de la que existen pocas poblaciones conspicuas y que ha sido propuesta como un nuevo cultivo oleaginoso para zonas áridas. Evaluamos una población en el Parque Nacional Lihué Calel (La Pampa, Argentina) con los objetivos de: 1) caracterizar la distribución espacial, la densidad y la estructura de tamaños, y 2) determinar cómo se relacionan estos factores con la producción de semilla. Las plantas de menor tamaño tuvieron menor acumulación de biomasa y producción de semilla, jerarquizando la asignación de biomasa hacia estructuras subterráneas. La biomasa individual es el componente que mejor explicó la variación del rendimiento por planta entre individuos de tamaño diferente.
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