The effects of the quantity and quality of radiation must be determined over a period of time in order to model the growth and development of peanuts (Arachis hypogaea L.). Two phytotron experiments were conducted in which light intensity and the duration of light were varied and Florigiant peanuts grown. Dry weights of leaflets, petioles and stems, leaf area, and number of flowers of young noncompetitive plants were measured at four-to five-day intervals over a 39- or 46-day growth period. Top dry weight increased curvilinearly with increasing photosynthetically active radiation becoming asymptotic above about 23 E m−2 day−1. Leaf area differed due to light treatment much as did top dry weight but differences in light did affect the leaf area per gram of leaflet and the leaflet to top ratio. That the latter also was related to top weight should be useful in modeling. The main stems were quite elongated under the low light treatments but light quality may be a factor in this response. The number of flowers was markedly reduced as less light was received by the plants. Regression techniques were used to fit an equation to describe a daily radiation factor that can be used in a simulation model. This daily radiation factor compared well with those from field estimates. These relations emphasize the importance of radiation only at quite low light levels. There was no apparent interaction between intensity and duration so use of total light should be valid.

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Author notes

1Paper No. 5359 of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina 27607. Operation of the phytotron unit of the Southeastern Plant Environmental Laboratory at North Carolina State University was supported in part by NSF Grant GI-28951. The use of trade names in this report does not imply endorsement by the North Carolina Agricultural Experiment Station of the product nor criticism of similar ones not mentioned.