1 Introduction 
Rice is the world’s most important food crop and a primary source of food for more than half the world’s population. Is the predominant staple for 15 countries in Asia and the Pacific, ten countries in Latin America and the Caribbean, one country in North Africa and seven countries in sub-Saharan Africa. In developing countries, rice accounts for: 715 kcal/capita/day, 27 per cent of dietary energy supply, 20 per cent of dietary protein and 3 per cent of dietary fat. Countries in Southeast Asia are heavily reliant upon rice. India accounts for nearly one-fourth (22%) of the rice produced in the world with the first place occupied by China. World rice production now is around 597.8 million tones grown over 151 million hectares with a productivity of 3.96 tones ha-1. India has an area of 50.00 million hectares under rice cultivation with an output of 104.10 million tones, which averages to around 4.00 tones ha-1.Dietary intake surveys from China and India reveal an average adult intake of about 300 g of raw rice per day.India produces some of the best quality rices in the world. Though a high-volume commodity, a class of aromatic, superfine premium rice has evolved its own market niches, making rice trade a commercial success internationally. A class of premium rice with specific grain characteristics, traditionally grown on either side of the Indus River, is popularly known as the basmatirice and these varieties are also known as “Queen of fragrance”. The superiority of basmati cultivars over other premium rice varieties is its superfine grains which have a distinct aroma, excellent elongation ability and the soft, flaky texture of the cooked rice (Siddiq and Shobha Rani, 1998). India’s revenue from the export of 8.44 lakh tones basmati rice during 2006~2007 was Rs 2 213 crore. 

Besides the much sought after basmati types which get high price in international markets, the country also abounds with hundreds of indigenous short grain aromatic cultivars and landraces grown in pockets of different states. Almost every state has its own collection of aromatic rices that perform well in native areas (Shobha Rani and Krishnaiah, 2001). These aromatic rices also possess exemplary quality traits like aroma, fluffiness and taste. However, the improvement of these rices is very much neglected as they lack export value perse. 

The aroma of rice plays a role in its consumer acceptability. More than 100 compounds that contribute to the aroma of rice have been identified. Some of these volatile compounds contribute to consumer acceptance of certain types of rice, whereas other compounds contribute to consumer rejection. The popcorn-like smell of aromatic rice stemming primarily from its 2-acetyl-1-pyrroline (2-AP) content is preferred by many consumers. Several methods are used to detect aroma like biting kernels, smelling vegetative tissue after warming or soaking in KOH and eating cooked rice (Sood and Siddiq, 1978). In recent years, actual quantification of 2-AP has been done using different distillation and extraction procedures. However, these methods are laborious, expensive, time consuming and require lot of sample for estimation. Keeping eye on these objectives the present investigation was carried out to know the extent of genetic variability in genetically diverse group of genotypes.

2 Results and discussion
The success of plant breeding depends on the extent of genetic variability present in a crop. The presence of genetic variability for economic traits is a key factor for improving productivity. Variability can be created by hybridization and so created variability need to be assessed in segregating populations. Therefore the present investigation was carried out to assess the extent variability in genetically diverse aromatic genotypes of rice. The results of the present investigation for various genetic parameters were as follows.
 
The analysis of variance was presented in table 1 and data on mean, range, phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), heritability (h²) and genetic advance as per cent mean (GAM) are character-wise presented in table 2. The figure 1 represents the entire genetic variability in the whole populations.