Continuous daily light period and temperature influence peanut yield in nutrient film technique

The peanut (Arachis hypogaea L.) is under investigation for use in the Nati onal Aeronautics and Space Administration's Advanced Life Support (ALS) pro gram as a food source for extended space missions. The objective of this st udy ass an evaluation of the effect of a continuous Light period combined w ith constant or diurnally cycled temperatures on pod and seed yield, plant biomass, harvest index, and gas exchange in 'Georgia Red' peanut grown hydr oponically under the nutrient film technique, Experiments were conducted in controlled-environment growth chambers. Treatments were light/ dark period s of 12/12 h or 24/0 h in combination with a constant 28 or 28/22 degrees C , Relative humidity was 70 +/- 5% and a photosynthetic photon flux (PPF) at canopy Level of 250 or 500 mu mol m(-2) s(-1) for 24/0 h and 12/12-h light periods, respectively. Plants exposed to 24/ 0 h Light produced more folia ge biomass, lower pod and mature seed yields, and lower harvest indices. Te mperature had no significant effect on foliage biomass yield. However, plan ts exposed to diurnal 28/22 degrees C produced higher pod and immature seed yield and a higher harvest index, The mean number of flowers reaching anth esis was higher among plants grown at a 12/12-h light period, regardless of temperature. Leaf net photosynthetic rates and stomatal conductance were h igher among plants grown at 12/12-h light period, regardless of temperature . The results suggest that, while light period influenced, foliage, pod, an d seed yield, temperature influenced foliage dry mass, immature seed yield, and harvest index.