Response of peanut (Arachis hypogaea) to temperature, photoperiod and irradiance 1. Effect on flowering

Abstract

For peanut ( Arachis hypogaea L.), the time to first flower appearance is shown to be little affected by photoperiod, but flower production is enhanced significantly in short-day photoperiods. Over 14 days, twice as many flowers opened in a 10-h than in a 16-h photoperiod. Therefore peanut can be classified as a short-day plant (SDP). Although time to first flower was little affected by photoperiod, temperature had a major and positive effect. A linear thermal-time model adequately described first flower appearance if we excluded mean temperatures above 30°C. The Spanish varieties manifested a higher base temperature (approximately 13.6°C) than either Valencia (12.5°C) or Virginia types (11.4°C). However, over a wider temperature range, quadratic curves were shown to be more accurate representations of time to first flower. The extrapolated base temperatures from curves were 2–3°C higher than those from straight line fits. Photon flux density ( Q ) close to saturating for photosynthesis gave earliest first flowering, and photoperiod effects could be seen only at very low Q . A major role for temperature in flowering of peanut is indicated by these data, with some modulation by photoperiod and irradiance.