Chlorophyll a fluorescence analysis can detect phosphorus deficiency under field conditions and is an effective tool to prevent grain yield reductions in spring barley (Hordeum vulgare L.)

Background and aimPhosphorus (P) is an essential macronutrient with major impacts on global crop productivity. Recent work showed that chlorophyll a fluorescence analysis can be used as a sensitive indicator of latent P deficiency across different plant species. Here, we demonstrate that chlorophyll a fluorescence OJIP transients are a powerful tool for early detection of P deficiency directly in the field.MethodsBarley was grown in a P responsive field. One treatment received 30kg P ha(-1) at sowing, four treatments were fertilized with P at 26, 35, 46 or 56days after sowing (DAS), respectively, and the final treatment did not receive any P throughout the experiment. Chlorophyll a fluorescence measurements, multi-elemental leaf analysis, and growth stage evaluation were performed 26, 35, 46, 56, and 69 DAS.ResultsPhosphorus deficiency during early vegetative growth irreversibly affected plant development including tiller outgrowth and grain yields. However, in the present study, yield reduction could be avoided if short-term P deficiency was corrected by application of P fertilizer no later than 35days after sowing, when plants had not yet entered the tillering stage. The chlorophyll a fluorescence OJIP transients were able to detect latent P deficiency in this critical phase, thereby providing an opportunity for avoiding a potential yield reduction of up to 27 hkg ha(-1). It was further noted, that chlorophyll a fluorescence analysis and P leaf tissue analysis should be performed during early vegetative growth, as probable remobilization of P within the plant during tillering and shoot differentiation masks the effects of P deficiency at the single leaf level.ConclusionsIt is concluded that chlorophyll a fluorescence analysis provides a unique opportunity for a timely detection and correction of P deficiency under field conditions to prevent yield reductions.