Climate change, a major issue in the discussion forums has been continuing from a long time and its impact on our agriculture created a lot of disturbance in the cultivation practices and yield. Industrialization, deforestation, unscientific cultivation practices, rice monocropping, and burning crop residues in fields from a long time resulted in heavy rains, drought, strong storms, heat waves, desertification, increased sea level and land degradation resulted in poverty and ultimately impaired GDP (gross domestic product). Increased population resulted in the land fragmentation, increased CO2 level and higher level of greenhouse gasses. At the same time, farmers are hardly in a situation to face it due to lack of resources, poor technical knowledge and small land holding.
Maize (corn), queen of cereal grains is the third most important food crop of India. Being a day neutral crop it can be grown throughout the year, preferably three cropping seasons i.e. Kharif, Rabi, and summer, but has less priority than rice and wheat comparatively either in cultivation or as a dietary source. However, it has tremendous utility in the daily life starting from baby food to entertainment, perhaps a rich source of fiber and nutritious diet. The unique feature of this crop is interior diversity. There are varieties of corn like sweet corn, babycorn, popcorn, pod corn, floury, starchy, blue corn named according to the utility and cob morphology. As a whole 52 % maize is utilized for poultry, 24 % as a food source, 11 % for starch, 11% for cattle feed, 1 % for brewing industry and 1 % as a seed source.
Maize has a better-withstanding capacity to climate change than rice and wheat. Biologically, it has a C4 mechanism of carbon fixation where loss of CO2 during photosynthesis is very less and energy conversion efficiency is very high. According to the recent studies, with the increased concentration of 700ppm of CO2 (over the current concentration of 400ppm), there was no effect on maize. Higher water use efficiency has resulted with higher CO2 concentration with optimum inputs. 10 C increased temperature resulted in 3-5 % yield loss but more effect was observed when increased temperature and higher CO2 concentration, the same condition may cause 15-24 % loss in rice and 21-30 % loss in wheat.
India is divided into traditional and non-traditional areas for maize cultivation; Bihar, Uttar Pradesh, MP, Rajasthan and hill areas of northeastern states are traditional areas and Karnataka, Andhra Pradesh, Tamil Nadu and Orissa are the non-traditional belt where maize is cultivated as a commercial crop. The major concern is with traditional belt farmers as their interest on maize is decreasing which resulted decreasing area under maize cultivation day by day. The main reasons may be due to the popularity of rice-wheat based cropping system, the poor performance of Rabi maize due to heat stress, soil erosion, lack of technology, processing industries and all the seed industries for seed marketing and research are located in the non-traditional area therefore, the research and changing climate are poorly considered. India sets a target of doubling the production by 2025 of 44 MMT with the current production of 25 MMT. To reach this goal there are several things need to concentrate:
1. Extending maize cultivation area across the country, popularizing and attracting farmers towards cultivation, post-harvest handling, processing, and export.
2. Popularizing winter (Rabi) maize. Around 53 % of maize cultivation is in Kharif season. During Kharif, the crop duration is only 120-130 days but less yield and more prone to stress especially disease and pest attacks. Whereas, rabi maize takes 170-180 days duration, favorable to seed production, good seed set and less incidence of biotic stress. However, increased temperature during flowering is only the problem which needs to be addressed by resistance breeding approaches. Summer maize may also be a greater source of feed with enhanced stay green traits, a good source of green fodder.
3. Along with the quantity improvement quality should also be considered. Already developed QPMs (quality protein maize with high lysine and tryptophan amino acids) and the bio-fortification programs need to focus on developing a locally adapted variety with balance multiple nutrients. This task is quite a time taking. However, CIMMYT Asia (International Centre for maize improvement) has already initiated this program in India.
4. QPMs need to be popularized and QPM based industrial products should be promoted.
5. Encouraging water and nutrient use efficiency, this has to focus on screening large genotypes and finding the best lines with efficient traits.
6. Regulated policy issues to promote industrial products prepared out of specialty corn. Eg. canned baby corn, sweet corn etc.
7. Improving the corn export quality and regulations to promote exports.
8. Boosting conservation agriculture (which minimizes tillage practices and crop duration) and the scientific package of practices.
9. Addressing soil problems by regular soil testing, adding more organic manure to the soil, avoiding the dumping of micronutrient bulks without the proper recommendation, may help to keep soil health intact.
Maize faces problems during reproductive stage if stress affects in the form of more heat, drought, water logging etc. Increased heat and drought causes pollen sterility, whereas waterlogging leads to increased anthesis-silking interval (ASI) ultimately poor yield. It is susceptible to soil pH change and nutrient imbalance as maize is an exhaustive crop. Among the cereals for changing climate maize is the best option but still to prepare it as a future crop there is a need to concentrate on some of the researchable issues and make the people and farmers understand its easy cultivation methods and multiple utilities. Points to enhance maize research and cultivation are:
1. Encouraging farmers for their active participation in the discussions on climate issues: Association between the neighboring farmers is very important to save the cost of cultivation in farm mechanization. Tribal people and farmers have their own ideology to tackle the climate related problem, discussions with them by the researcher's help in coming up with the better ideas. Parallel to climate change we should also change our focus and consumption habits toward other food and millets to increase the diversity.
2. For addressing the biotic and abiotic stress in a combined way, gene deployment and gene pyramiding are the best options where different trait responsive genes identified through marker assisted selection (MAS) or Marker assisted Backcross breeding (MABB) for different pest/disease/drought/other stress and genes carrying geographical importance are introgressed in a single genotype.
3. Modern approaches like genome re-sequencing help to find the rare alleles (alternate form of a gene) responsible for a definite trait expression. Eg. Enhancing nutrition or better plant adaptability.
4. Genotyping by sequencing, next generation sequencing, finding QTLs (Quantitative trait loci) and incorporating them into the popular local adoptive variety are the tools to make strong plants.
5. Rather than targeting the whole country, it is better to target and focus on a specific region to develop multipurpose lines and making them strong.
6. Boosting the research centers and private companies to remote areas where maize growth has a better opportunity. Private seed companies must be encouraged for quality seed production and supply in these areas.
7. High throughput phenotyping: With the help of poly captors, multidimensional camera the minute changes occurring in a large area even on a single plant can be keenly observed and it made stress forecasting very easy.
8. Single cross hybrid (SCH) maize is popular than composites and open pollinated varieties as it is uniform, high yielding, easy to produce, more responsive to inputs etc. Across the country, only 37-43 % land is under SCHs. Now the seed production is supported with doubled haploid production to maintain uniformity and produce the seeds on a large scale. Producing SCH is a cheaper and easy technique, however, there is a need to screen germplasm lines collected from the different locations to find the suitable haploid inducer lines.
9. GM maize: Maize resistant to certain insects, weeds in America and water use efficiency in Africa, are grown from almost 15 years but very few harmful incidences are reported. If this technology will be supported, maize may have better future in India.
10. Seed of Discovery (seeD): ‘Seeds of Discovery’ (SeeD), a novel initiative by CIMMYT has initiated intensive exploration of phenotypic and molecular diversity of maize germplasm conserved in the CIMMYT Gene Bank; this is expected to aid in effective identification and use of novel alleles and haplotypes for maize improvement. Some research institutes, CIMMYT and allied programs like HarvestPlus (micronutrient enhancement) and German funded projects, BISA (Borloug Institute for South Asia), Ministry of Environment & Forests (MoEF) and recently, Bill & Melinda Gates foundation are funding for research to address climate change issues. Multi-institutional efforts are required at the global level to systematically explore the maize germplasm to diversify the genetic base of elite breeding materials, create novel varieties and counter the effects of global climate changes.
Popularizing and extending the area of any crop is not so easy, it all depends on people/traditional belief, consumption habit, preference for the crop, nutritional importance and finally the taste. The target production of 44 MMT by 2025 with better quality and increased export potency needs combined efforts of the scientists of all the related discipline working on maize and farmers cooperation. If timely introduced technologies and proper inputs material reach the farmer, no doubt we may face the climate change challenge boldly. However, combined genotypic+phenotypic+environmental effect studies along with better management strategies cannot stop the country to attain the target food production.