ASGSB 1998 Annual Meeting Abstracts

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PRODUCTIVITY OF COWPEA CANOPIES WITH INTRACANOPY LIGHTING USING ELEVATED CARBON DIOXIDE AND DIFFERENT PHOTOPERIODS IN CONTROLLED ENVIRONMENTS. J.M. Frantz, R.J. Joly, and C.A. Mitchell, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907-1165

Plant-growth lighting for long©term manned space missions will be a major source of power consumption in advanced life-support systems. Intracanopy lighting, a lighting technique that allows plants to grow through and around multiple layers of low intensity lamps, may help reduce the energy necessary for crop production. Results with cowpea (Vigna unguiculata L. Walp ‘IT87D-941-1'), a legume species with edible leaves, pods, and/or dry beans, indicate that, at similar energy consumption totals, intracanopy lighting yields 20-25% more, have a 30-35% higher harvest index, and use light energy nearly twice as effectively as traditional overhead (above canopy) lighting strategies. Optimization of intracanopy lighting can improve the yields of crops while further increasing the efficiency with which the crops are produced. Increasing [CO₂] from ambient levels to 1000 µmol mol^-1 improved edible yield totals and yield rates by 20% without the use of additional light energy. Also, a reduction in photoperiod from 24 h to 18 h significantly improved energy efficiency without a significant reduction in yield. Further steps in the optimization of photoperiod and [CO₂] are expected to improve upon the efficiency of crop production using intracanopy rather than traditional lighting systems. Optimization of intracanopy lighting may improve the sustainability of long-term manned space missions by reducing the energy requirements for crop production. Research supported in part by NASA grant NAGW©2329.

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