Morphometric characteristics and nectar potential of Ocimum basilicum L. var. genovese (Lamiaceae) in relation to microclimatic and edaphic environmental factors

Abstract

Background and Purpose: Ocimum basilicum L. var genovese was grown from seed in selected soil types (eutric cambisol, fluvisol and humoglay) in order to analyse its morpho-physiological flower preference and morphometric characteristics of aerial parts in relation to microclimatic conditions and physico-chemical soil properties. Materials and methods: The soil texture was analyzed using the "pipette method", concentration of CaCO(3) was determined using the volumetric method and percentage of humus and carbon was detected using Tiurin's method. Electrometric method was used for chemical reaction of soil. The amount of nectar per flower was assessed using microcapillary method. Morphometric analysis comprised measurements of plant height, length and width of leaf internode length, petiole length and leaf number. Results and conclusions: Considering the whole flowering period, the most luxuriant growth and the highest intensity of secretion was recorded on eutric cambisol. Results of morphometric analysis showed that statistically significant difference existed between the plants on eutric cambisol and humoglay (p<0.05). With respect to diurnal dynamics of nectar secretion, a pattern with a single daily peak was recorded, irrespective of the type of soil Daily maximum was recorded at 8 am on eutric cambisol (0.104 mu l/flower), and at 10 am on fluvisol (0.166 mu l/flower) and humoglay (0.103 mu l/flower). After reaching the highest values, secretion had decreasing tendency toward evening, and minimal nectar amount was sampled at 6 pm in all soil types (0.006-0.016 mu l). Surprisingly, on nectar collecting day in June, the highest total daily nectar amount per flower was measured on humoglay (0.351 mu l) and the lowest on eutric cambisol (0.288 mu l). Air humidity and evaporation were positively and temperature negatively correlated with diurnal dynamics of nectar production in all soil types.