• Quality in tobacco is currently an object of subjective evaluation and best defined as "that for which the buyer pays money".
• Thus quality determines the price of the tobacco leaves produced for marketing purposes.
• Sugars are considered to have a positive influence on quality while nitrogenous compounds, a negative one.
• It is necessary for a leaf to have too much sugar and some nitrogenous constituents because in absence of either of the two the smoke is insipid and lacks character.
• Thus the commercial value of a leaf is judged by its suitability for specific purposes of manufacture viz. tobacco used for smoking purpose must have a combustibility and fine aroma.
• In general the leaf characters, chemical composition of leaves, burning quality and aroma are the most important factors in determining the quality of a tobacco.

• Leaf character is primarily hereditary in nature but it may slightly be modified with the growing season, nutrient conditions, planting density, topping and de-suckering etc.
• Size of leaves is a very important factor in cigar types than in most others because for cigar-wrappers normally the medium and shorter leaves are preferred.
• The prominence of leaf-veins is of a greater significance in cigar-wrapper types. Fine vein constitutes an essential characteristic of a high grade cigar wrapper.
• The angle formed by midribs and principle veins makes a better look of cigars and helps in fixing a higher price.
• Usualy midribs and webs are waste products to the extent of 20-30 per cent in tobacco leaves and therefore, they affect the economy in usage of the products.
• Leaf thickness is the next important factor for determining the value of the produce as the leaves of different thickness are used for different commercial purposes.
• Leaves used for pipe smoking mixtures and cigar wrappers are thinnest of all types, while good cigarette leaves and plug fillers usually are somewhat thicker. Leaf thickenss is partly controlled by growing season, cultural practices, etc.
• Crop grown under drought conditions produces small, thicker and heavier leaves, which are relatively less elastic in nature and cannot be used as wrapper or filler.
• Apart from this the leaves produced under drought conditions have more sticky and gummy secretion which is composed of etheral oils and resins. Although they donot affect the quality and aroma but the look becomes deceptive.
• Leaf-colour, its depth and uniformity in shade over the leaf surface is equally important in selecting the grade of the leaf within the type.
• Leaves of light colour, being mild tobaccos, may present a high lustre while the dark coloured leaves, which are strongest ones, may have a dull and lifeless appearance.
• On individual plant the lower leaves are light coloured and top leaves are of darker shades.

• Tobacco leaves contain a number of chemical compounds (alkaloids) which influence their quality. Of these polyphenols and carbonyls have an important bearing on flavour and aroma.
• Cellulose and minerals are deciding base materials for combustion. Glycosides cause bitterness in leaves.
• Soluble carbohydrates, especially sugars, are considered to have a positive influence on quality and nitrogenous compounds a negative one.
• Nicotine is the single compound which over rules all other chemicals in governing the quality.

The factors affecting tobacco leaf qualities can be divided into three major groups.

• Genetical factors
• Ecological factors
• Cultural factors

• Curing behaviour, flavour, aroma, body, texture, colour retention, burning qualities etc. are expected to be genetically controlled to a greater or lesser extent, viz., sugar content is higher in flue-cured tobacco than in any other types.
• Similarly, carbohydrate content and nicotine content were found to be different in various types of tobacco.
• Position of leaves on stalk influences the leaf quality as the bottom leaves are relatively thin, light in weight and body, light in colour, mild and have good burning qualities.
• Passing up the stalk, the leaves become progressively thicker, heavier in weight and body rough, more gummy, stronger, darker in colour, more aromatic, but of poorer burning qualities.
• As regards the chemical composition, in general, passing from the lowest to the top most leaves of fully matured plant, there is a progressive increase in content of total nitrogen, protein, nicotine and ammonia and a decrease in total ash, calcium, magnesium and pH value. The content of soluble carbohydrates is lowest in the upper leaves and highest in the middle leaves of the plant.
• Thus, it is observed from the same plant that on an average bottom 5-6, middle 2-4 and top 1-2 leaves formed the three grades of qualities viz. superior, medium and inferior respectively which is roughly in the proportion of 6:3:1.

• Tobacco soil must be well drained, properly aerated with low inherent fertility. Soils with high sandy surface and friable sandy loam sub-soil surface, low content of organic matter, acidic reaction (desirable pH 5.0-6.0) and good amount of potash, phosphoric acid and iron are preferred for quality leaf production.
• Heavy soils produce tobacco with higher nitrogen than the sandy loam or sandy soils. Tobacco grown on saline lands absorbs moisture quickly before and after drying, changes colour rapidly during storage and has poor burning qualities.
• These are mainly due to large quantities of Chlorine (more than 0.01 per cent in soil and more than 10 per cent in leaf) which the plant takes up from the soil. Tobacco grown on paddy lands and tank beds becomes bleached.

• Temperature, humidity, rainfall and its distribution during the growing period of tobacco have considerable effect on the quality of leaf.
• High temperature and low relative humidity have harmful effects on leaf burn but the leaves are thick and aromatic.
• In lower temperature, due to slower rate of metabolic processes, the leaf does not ripen full and does not develop the desirable qualities.
• The desirable range of temperature for quality production of tobacco is 70-90° F.
• Rainfall desirably ranging from 50 to 125 cm during growig season of tobacco results in leaves with light weight, thin texture, light colour, less gummy, light body, reduced nicotine content and aroma.