Characterization of Physiology, Photosynthesis, and Nutrition Based on Induced Deficiencies of Macro- and Micronutrients in Basil (Ocimum basilicum L.)

Basil (Ocimum basilicum L.) contains abundant nutrients and is considered an economically important edible vegetable. The optimal nutrient levels will increase the productivity and basil quality. However, prominent research on basil regarding the diagnostic nutrient deficiency standard and the corresponding nutrient uptake is still scarce. To this end, the basil plants were hydroponically cultured and subjected to one of 14 nutrient solution treatments, corresponding to the omission of a single nutrient element (designated as -N, -P, -K, -Ca, -Mg, -NH4+, -NO3−, -S, -Fe, -Mn, -B, -Zn, -Mo, and -Cu) and a complete nutrient solution (CS) as the control. The most common nutrient deficiency symptoms were chlorosis, stunted roots and growth, and even leaf necrosis and abscission, in particular of -N, -P, -NO3−, and -Fe. We also found that basil is a NH4+-sensitive species. The photosynthetic capacity (photosynthesis pigments, Fv/Fm ratio, and greenness index) was disturbed to varying degrees when a single nutrient was omitted from the nutrient solution. Additionally, the omission of a specific single nutrient confers significant differences in the tissue nutrients, regardless of the macronutrients and micronutrients considered. Concomitantly, multivariate analysis suggested the correlations among certain important nutrients were distinctly different under different treatments (correlation analysis); the influences of different nutrient deficiencies on the tissue nutrient concentrations showed similarity (principal component analysis). Collectively, the growth, physiological, and biochemical changes studied in this trial not only improved our knowledge for diagnosing nutrient deficiency symptoms for practical cultivation but also provided a comprehensive understanding of the internal nutrient associations in basil.