The effect of shade on Physiol- Morphplogical characteristics and essential oil of Mint

Mint is one of the most important medicinal and aromatic plants in the world، however، the effects of shading levels on growth and quality of mint accessions have not been well documented. Therefore، the purpose of this experiment was to determine the effects of five shade levels on production of nine mint genotypes. For this purpose a completely randomized design with three replications was conducted during the 2012-2013 growing season in pots in open space in Chah anari field in Isfahan University of technology. Treatments were: (0 (full sun)، 20-30% shade، 40-50% shade، 60-70% shade and 80-90% shade) as different environment and 9 species of Mint: (Karaj، Hamedan and Esfahan (M. longifolia)، Tabas، Ghazvin and 7-1 (M. piperita)، 2-1، 11-3 and Bojnord (M. spicata) intensities. Shoot fresh and dry weights، root fresh and dry weights، leaf total chlorophyll and chlorophyll، a and b and carotenoid contents، essential oil content and yield were measured. The records data were analyzed using combined analyses of data. The highest shoot fresh weights (156/46 g per pots) were was measured under 20-30% shade in Karaj. The highest shoot dry matters (46/60 g per pots) were detected in Esfahan genotype under control (full sun full). The highest root fresh weights (236/47 g per pots) were was recorded for Karaj genotype under 20-30%. The highest root dry matters (73/03 g per pots) were measured for Karaj genotype under 40-50%. The highest chlorophyll b (6/89 mg /g) was measured in Esfahan under sun full. The highest carotenoid contents were was detected in Ghazvin genotype under 20-30% shade level. The highest percent essential oil (1/82%) was recorded in Tabas genotype under 20-30%. The highest essential oil yield essential oil (80/16 mg/g) was registered in Esfahan genotype under 20-30%. Maximum. Under control and 20-30% shade Esfahan genotype، under 40-50% shade Karaj genotype، under 60-70% and 80-90% 3-11 genotype produce highest shoot dry matter. Highest percent essential oil under control level، 20-30% shade and 40-50% shade in Tabas، under 60-70% and 80-90% in 1-2 genotype obtained. Results of this experience showed that measurementd traits were d characters correlated todepends on the genotype and shade laevel and it is possible to selection tolerant genotypes. Esfahani genotype under control and 20-30%، Keraj genotype under 40-50%، 3-11 genotype under 60-70 and 80 to 90% shadings produced the highest shoot dry yield، respectively. Whereas، the highest essential oil content was recorded in Tabas genotype under control، 20-30 and 40-50% shadings and in 1-2 gentype under 60-70 and 80-90% shadings.