Assessment of common bean responses to light spectral composition and microbial inoculation using non-destructive methods
¹Latvia University of Life Sciences and Technologies, Faculty of Agriculture and Food Technology, Institute of Soil and Plant Sciences, 2 Liela street, LV3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Agriculture and Food Technology, Food Institute, 2 Liela street, LV3001 Jelgava, Latvia
*Correspondence: Ina.Alsina@lbtu.lv
Abstract:
. Non-destructive methods are increasingly used to evaluate plant physiological status. This study assessed the applicability of spectrometry and chlorophyll fluorescence for monitoring common bean (Phaseolus vulgaris) responses to light quality and microbial seed inoculation. A two-factor growth chamber experiment was conducted using LED lighting of equal intensity but different red-to-blue ratios (1:1, red-dominated, blue-dominated) and seeds that were either uninoculated or inoculated with Rhizobium phaseoli strains or Proseed-Met. Non-destructive measurements were performed on the same leaves using a spectroradiometer RS-3500 and a FluorPen FP110 fluorometer. Vegetation indices were calculated to evaluate stress, pigment content, senescence, and water status, while fluorescence parameters described photosynthetic performance. Spectrometric indices more clearly reflected light treatment effects, showing higher pigment content under red light, greater senescence under balanced light, and increased stress under red-dominated spectra. Fluorescence parameters were mainly affected by microbial inoculation and were higher in inoculated plants. Limited correlations between the two methods indicated that they capture different aspects of plant physiology. Blue-dominated light increased pod number, whereas red light reduced pod and seed mass. Microbial inoculation alone did not significantly affect yield, but the highest seed yield was observed in Rhizobium-inoculated plants under blue light. The results highlight the importance of light spectral composition for bean productivity and support the combined use of spectrometric and fluorescence methods for comprehensive physiological assessment.
Key words:
chlorophyll fluorescence, LED, Phaseolus vulgaris, spectrometry, vegetation indices