MORPHOLOGICAL AND ESSENTIAL OIL CONTENT DIVERSITY OF IRANIAN MINTS (MENTHA SPP)

Document Type: Regular Paper

Authors

1 Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan 84156, I. R. of Iran

2 Department of Agronomy and Plant Breeding, College of Agriculture, Isfahan University of Technology, Isfahan 84156, I. R. of Iran.

Abstract

There is little information available on morphological and agronomic traits, as well as
chemical compositions of Iranian mint landraces. This study was conducted to investigate the
morphological, agronomic and oil content characteristics of Iranian mint landraces using twelve
landraces, three of which belong to Mentha longifolia, and the remaining, Mentha spicata L, originated
from central regions of Iran. Days to 50% and 100% flowering, plant height, number of lateral branches,
leaf length, leaf width, herbage yield per plant, number of nodes per main stem, number of nodes per
lateral branch, spike length of main stem, number of spikes per plant, height of lateral branches and
spike length of lateral branches were recorded and used in this study. The results showed the significant
differences among landraces for all tested traits with the exception of the number of nodes per lateral
branch. Two accessions, including Mzin3 with 1.9 ml/100g essential oil content, and Mzin6 with 2.1
ml/100g essential oil content, produced the highest essential oil content. Mzin3, with15.9 g/plant herbage
dry yield and Mzin6 8.1 g/plant, produced the highest and lowest herbage yield. Genotypic and
phenotypic coefficients of variation were high for the spike length of the main stem (32.3%, 29.7 %), the
number of spikes per plant (41.7%, 28.5%), and the essential oil content (38.5%, 34.1%), and was low
for days to 50% flowering (11.9%, 10.7 %), days to 100% flowering (9.2%, 6.5%) and number of nodes
per main stem (9.7%, 6.9%). Stepwise regression analysis indicated that leaf length justified 53 percent
of the total variation and was accounted as the most important component of essential oil content.
Cluster analysis divided the landraces into 3 groups, each of which having 5, 3 and 4 clones. The number
of nodes per main stem, number of lateral branches, spike width of main stem, leaf width, days to 50%
flowering, plant height and nodes per lateral branches were the major sources of diversity among the
mint clones. Strong association was observed between leaf length and essential oil content (r = 0.73).
Therefore, under tested environmental conditions, leaf length may be used as a morphological criterion
for selecting clones with high essential oil content in mint.

Keywords