NEUTRAL VOLATILE AROMA CONSTITUENTS OF LANKA TOBACCO ( NICOTIANA TABACUM L.) IN RELATION TO NITROGEN SUPPLY AND LEAF POSITION

Abstract

Lanka tobacco, an indigenous air-cured cheroot tobacco grown predominantly on alluvial flood plains of river Godavari in Andhra Pradesh, is known for its characteristic pungent taste and strong aroma. A field experiment was conducted during 2010-11 in Rekhapalli, Khammam district, Andhra Pradesh to study the effect of nitrogen levels (Recommended practice; N1=300 kg/ha and farmers’ practice; N2=1000 kg/ha) and leaf position (bottom, middle and top) on neutral volatile aroma constituents in lanka tobacco. The neutral volatile compounds detected by GC-MS included degradation products of carotenoids, thunberganoids, terpenoids and neophytadiene. As shown by their relative content in neutral volatile fractions, neophytadiene (36%), thunbergol (2.35%), megastigmatrienone isomers (6.86%), 3-hydroxysolavetivone (8.47%), solavetivone (1.44%), solanone (1.41%) and Z-Abienol (1.37%) were some of the major compounds that significantly contribute to smoke flavour. The neophytadiene content was higher in N1 treatment (11.8%) over N2 treatment. The four isomers of megastigmatrienone were present in all the leaf positions in both the nitrogen treatments and megastigmatrienone isomer-2 was in maximum content. Megastigmatrienone isomers content increased with change in leaf position from bottom to top with exceptions. The total phenylalanine related compounds were more in N1 over the N2 treatment. Maximum content of neutral volatiles were present in the middle (98.53%) and top position (98.88%) leaves compared to bottom leaves (70.41%) in N1 treatment. Thus the leaf position showed significant effect on neutral volatile compounds, whereas the variation between two nitrogen levels in aroma compounds was significant only in bottom position leaf . Results revealed that tobacco from both middle and top positions showed maximum accumulation of neutral volatile aroma constituents at 300 kg N/ha.The recommendation of 300 kg N/ ha for lanka tobacco was found to be optimum for accumulation of maximum neutral volatile aroma constituents for its pungent taste and strong aroma compared to farmer’s practice (1000 kg N/ha).