Intercropping Stokes Aster: Effect of Shade on Photosynthesis and Plant Morphology
- E. J Callan and
- C. W. Kennedy
Stokes aster [Stokesia laevis (Hill) E. Greene] is a potential new crop source of an epoxy acid but grows slowly and does not yield the first summer. It could be intercropped that year. To evaluate Stokes aster's response to intercrop shade, plants were grown under 1010 [high light (HL)], 320 [medium light (ML)], or 120 [low light (LL)] μmol m−2 s−1 photosynthetic photon flux density (PWD) for 50 d prior to measurements of photosynthetic rate, light compensation point, light saturation point, chlorophyll concentration, and morphology of whole plants. Near light saturation points, LL and ML plants had the highest net CO2 assimilation based on leaf area and ML plants were highest based on land area. High light plants were least efficient due to a vertical leaf orientation. As environment light intensity (LI) declined, plants had more chlorophyll per unit dry weight (DW), a higher chl b/chl a ratio, less leaf DW, less leaf area, and a lower root/shoot ratio. Light compensation points were 25, 55, and 185 μmol m−2 s−1 PPFD for LL, ML, and HL plants, respectively. Saturation points were between 400 and 800 μmol m−2 s−1 for LL plants and between 800 and 1500 μmol m−2 s−1 PPFD for ML and HL plants. In an intercrop, stokes aster should produce efficiently on a leaf area basis but less efficiently on a land area basis when grown under a LI of 120 μmol m−2 s−1 or less. Growth in full sun after the overstory crop is harvested would not be a problem for intercropped plants.
Copyright © 1995.