भारत में एकल क्रॉस संकर के विकास के माध्यम से मक्का में कि‍स्‍म सुधार

Maize (Zea mays L.) is the most widely distributed crop of the world being grown in tropical, sub-tropical and temperate regions up to 500 and from sea level to more than 3000m under irrigated to semi-arid conditions. Being a versatile crop, it adapts easily to a wide range of production environments.

In India, maize is the third most important cereal after rice and wheat that provides food, feed, fodder, and serves as a source of basic raw material for the number of industrial products,viz. starch, protein ,oil, alcoholic beverages, food sweeteners, cosmetics, bio-fuel, etc. No other cereal can be used in as many ways as maize. Virtually every part of the plant has an economic worth.

The grain can be consumed as human food, fermented to produce a wide range of foods and beverages, fed to livestock, and used as an industrial input in the production of starch, oil, sugar, protein, cellulose, ethyl alcohol, etc.

The leaves, stalks, and tassels can be fed to livestock, either green (in the form of fodder or silage) or dried (in the form of Stover). The roots can be used for mulching, incorporated into the soil to improve the physical structure, or dried and burned as fuel.

In India, maize is cultivated over 8.26 million ha with a production of 19.31 million tons having an average productivity of more than 2.4 tons/ ha, contributing 8.5 % to the Indian food basket. It occupies an important place as a source of human food (25%), animal feed (11%), and poultry feed (52%), starch (11%), brewery (1%) and seed 1% (Fig.1).

The growth rate of area (2.83 %), production (30.93 %) and productivity (27.35%) over the past years, has shown a remarkable increase as compared to other principal cereal crops. No other cereal crop has shown the high growth rate as of maize. 

Maize breeding activities in India

Maize breeding strategy in India has gone through many phases of switch -over since the inception of All India Coordinated Research Project (Fig.2) on maize in 1957. However, the last three to five years have been the landmark years since the adoption of high yielding hybrids on farmers' fields proved as critical input for achieving high growth rate in maize.

The breeding activities have therefore, been re-oriented towards the development of high yielding single cross hybrids for different agro-ecological regions of the country seeing the strength of two-parent crosses for high yield and tackling the problems posed by biotic and abiotic stresses.

This has been duly supported by development of vigorous, productive and genetically diverse inbred lines that have good performance per se as well as in cross combinations. 

Focus on Inbred-hybrid technology

The major mandate of AICRP (Maize) as well as DMR is to evolve and disseminate inbred-hybrid technology. With the urbanisation, specialty corn has gained a great acceptability among the masses. Their demand in Indian market has gone up. Sweet corn and baby corn hybrids/ varieties are sought to cater to the demands of peri-urban agriculture.

Over the years 131 hybrids have been developed and released since 1961; four dozen are public-bred single cross hybrids of different maturity ( extra-early, early, medium and late) and suitable for cultivation in different agro-climatic conditions of the country (zones 1 to 5, kindly see the Fig .2).

Since 2005, as many as 23 normal, seven Quality protein maize (QPM) and one each of baby corn and sweet corn single cross hybrids have been released. The detailed information on these hybrids including pedigree, characteristic features, area of adaptation, etc, has been provided in Table 1.

Table 1: Hybrids Developed and Released for Cultivation in India during last three years.