The field pea crop in S.W. Australia. I. Patterns of growth, biomass production and photosynthetic performance in genotypes of contrasting morphology

Abstract

Biological yield and photosynthetic performance of six field pea genotypes of contrasting foliar morphology and growth habit were studied in a water-limited field environment at Wongan Hills, Western Australia. Dundale and Wirrega were tall, indeterminate, scrambling and conventionally leaved; Dinkum, L82 and L80 (semi-leafless) and Progreta (tare-leaved) were semi-dwarf and more erect. Green area index (green leaf area per unit of ground area), green area duration (time integral of green area), crop growth rate (rate of dry matter accumulation per unit ground area) during early spring, net photosynthetic rate (CO2 exchange rate per unit green area or unit green weight) and net assimilation rate (rate of dry matter accumulation per unit green area) all influenced crop productivity. Shoot and root biomass was highest in Wirrega, due mainly to superior green area index, extended green area duration and maintenance of high growth rate during pod fill. Inverse relationships amongst genotypes were evident between green area index and net assimilation rate, and between green area index and CO2 exchange rate of green area. Total net photosynthesis of the tendrils of semi-leafless types was similar to that of leaflets of conventional types, due mainly to larger biomass of tendrils compensating for poor photosynthetic rates. The poor growth of semi-leafless and tare-leaved types was attributed to lower vigour, green area, ground cover and photosynthate production. Future selection of such types for water-limited environments should concentrate on increasing shoot height, node number per plant, stipule and tendril size and photosynthetic efficiency of green area.