Quality Protein Maize (QPM): Importance and production requirements

Abstract

Quality Protein Maize (QPM): Importance and production requirements Ramesh Kumar, DP Chaudhary, AK Das and Sujay Rakshit ICAR - Indian Institute of Maize Research, Ludhiana

Introduction The present scenario of increasing population puts pressure on agriculture not only to increase production and productivity but also the grain quality. It is imperative that increasing production of food crops to ensure food and nutritional security of the nation has become a necessity rather a matter of choice. However, the challenge to meet the growing demand for food seems to be a daunting task due to rapid reduction in agricultural land, reduced availability of water resources and climate change. Moreover, ensuring the nutritional security or improving the nutritional status of the poorer section on sustainable manner is an added challenge. The present food production scenario indicates that much of the future food production is expected to come from coarse cereals, particularly maize because of its highest yield potential as compared to any other food crop. Maize has already credited as queen of cereal and further due to its high content of carbohydrates, fats, proteins and some of the important vitamins and minerals, it has also acquired a well - deserved reputation as ‘poor man’s nutri - cereal’(Kumar et al .,2012). Maize contributes 15% of the world’s protein and 19% of the calories derived from food crops (Vasal SK, 2002). Millions of people in the world, and particularly in developing countries, derive a part of their protein and daily calorie requirements from maize (Mbuya et al.,2011). In recent years the diversified uses of maize as food, feed and as an industrial raw material is also increasing. In addition to this maize is part of the livestock - to - meat cycle across the world (Tanumihardjo et al., 2019). The food processing industries are coming up with new value - added products of corn like flakes, chips, biscuits, sooji etc. Increased demand from consumers has led to higher per capita consumption and demand for maize. Improved growth in Indian economy has increased per capita income thereby improving the purchasing power of its people. The consequence of all these events has led to change in the food habits with an increased non - vegetarian population of the country. The increased non - vegetarian populations had its own cascaded of events on food/feed and meat industries. The increased demand of meat has increased the demand of maize from poultry and piggery feed industries. In this particular context, quality protein maize (QPM) can play a crucial and very important special role in ensuring the food and nutritional security of the country. Nutritive Value of Quality Protein Maize The maize grain on an average contains around 15 % moisture, 8 - 12 % protein, 2 - 4 % fat, 3 % fibre, 67 - 72 % starch and around 1.5% minerals. Hence it is a good source of carbohydrates, fats, proteins and some of the important vitamins and minerals and, therefore, termed as nutri - cereal. Majority of the population depend on cereals for their livelihood and maize is the staple cereal food for several million people, especially in the developing countries across Sub - saharan Africa who derive their >30% of the total dietary protein and >20% of the daily calories requirements from maize as it supplies many macro and micronutrients necessary for human metabolic needs. The kernel protein is made up of five different fractions, viz., albumin 7 %, globulin 5 %, non - protein nitrogen 6 %, prolamine 52 % and glutelin 25% and the left - over 5 % is residual nitrogen. The quality of maize protein is poor due to the presence of large concentration of an alcohol soluble protein fraction, prolamine also known as zein in the endosperm. Zein is very low in lysine and tryptophan content and since this fraction contributes more than 50 percent of the total protein, the maize protein is, therefore, deficient in lysine and tryptophan content. On the other hand, zein fraction contains very high amount of leucine and imbalanced proportion of isoleucine. The ill - proportion of four essential amino acids in normal maize kernels results in poor protein quality of traditional maize kernels affecting its biological value i.e. the availability of protein to the body. Thus, the composition of maize protein has an in - built drawback of being deficient in two essential amino acids, viz., lysine and tryptophan. However, high - quality protein sources, such as eggs, meat, dairy products and legumes provide total or complementary sources of these amino acids, but many rural poor have limited access to these foods. Therefore, populations depending on maize as their staple food generally show the protein deficiency disorders like Marasmus and Kwashiorkar. In addition, maize lacks vitamin B and also due to high concentrations of phytate some minerals in the maize grain have low bioavailability. Therefore, a need was felt to improve the biological value of protein in maize varieties. In early 1960s the breeders at Purdue University obtained the natural mutants of maize which have soft and opaque grains. The biochemical and genetic analysis of mutant kernels revealed that they contain higher concentration of lysine and this nutritionally superior maize was named opaque - 2 maize, after discovering that “opaque - 2” single gene mutation is responsible for the improved protein quality (Mertz et al., 1964). It was mentioned that the original mutants obtained were soft and opaque, but they have some draw - backs like higher susceptibility to storage and ear rot. Therefore, to overcome this problem International Center for Maize and Wheat Improvement (CIMMYT) introduced endosperm modifier genes through continued recurrent selection breeding programme led by Dr. S. K. Vasal and team. As a result, hard endosperm o2 stocks were developed and were designated as quality protein maize (QPM) to distinguish it from soft o2 strains. Quality protein maize (QPM) was created by selecting genetic modifiers that convert the starchy endosperm of an opaque2 (o2) mutant to a hard, vitreous phenotype. However, not all of the hard endosperm o2 lines retained high levels of the critical amino acids. Later the genetic studies on QPM have shown that there are multiple, unlinked o2 modifiers (OPM), but their identity and mode of action are unknown. In QPM the concentration of zein is lowered by 30 percent, as a result the lysine and tryptophan content increases in comparison to maize. The lower contents of leucine in QPM further balance the ratios of leucine to isoleucine (Table1). The balanced proportion of all these essential amino acid in QPM enhances the biological value of protein (Table - 2). The true protein digestibility of maize vis - à - vis QPM is almost same, but the biological value of QPM is just double as compared to maize varieties (Fig1), rather it is highest among all cereals and pulses (Fig1). The reason behind it is that all cereals except QPM are deficient in lysine, an essential amino acid and all pulses are deficient in another essential amino acid methionine. Maize breeders have developed several QPM hybrids by incorporating opaque - 2 mutant gene modifiers in different parental lines. QPM looks and taste like normal maize, but it contains nearly twice the quality of lysine and tryptophan along with balanced amino acid profile. QPM as Food and Nutritional Security In India, tribal population constitutes approximately 10% of the total population and is found in most parts of the country especially in the states of Madhya Pradesh, Assam, Nagaland, Gujarat, Chhattisgarh, Jharkhand, etc. Thus, a sizable tribal population exist which is economically deprived. Further, most of tribal population depends on maize as their basic diet. In these areas the scope for QPM to ensuring food and nutritional security is paramount. Substituting maize with QPM is a viable option for ensuring their nutritional requirements. Tribal peoples are acknowledged to have very close association with ecosystem and environment because of their dependence on nature directly for daily requirements. However, the problem of malnutrition arises due to inadequate intake of nutrients in the diet. The situations are almost same in some African countries. Several studies are conducted on human beings and animal and are continue to be conducted on positive health benefits of QPM consumption in their daily diet. Gunaratna et al., 2010 reported that consumption of QPM instead of maize leads to an increase in growth rate of height and weight by 12 and 9%, respectively in infants and young children coming from population with mild to moderate under nutrition where maize is the significant component of the diet. This happened due to the higher biological value of QPM as compared to the maize (Table 2). The results are encouraging and based on these results the Indian policy makers can think of providing QPM in the tribal belt or in the areas where there is a problem of malnutrition. Government of India can also think of introducing QPM in public distribution system and QPM based food in mid - day meal in schools and Aanganwadis. Government of India has already started Tribal - Sub Plan (TSP) and under this programme the Directorate of Maize Research has provided QPM hybrid seeds for cultivation in the areas where tribal population is more. Some on - farm trainings have also being organized in these areas for creating awareness to use QPM as staple food. QPM and Animal feed Maize is an integral part of the animal feed used in India and outside. There are several studies where maize has been replaced by QPM as an ingredient of animal feed and encouraging results have been observed in case of broilers, chickens and pigs. Feed trials have repeatedly shown that pigs fed with QPM grow twice as fast as those fed with commercial maize (Krivanek et al., 2007). Some nutritional studies with pigs and chicken diets have shown that performance is improved when QPM is substituted for maize without any additional protein supplement. In broiler diet, the substitution of QPM for maize at a rate of 60% substantially reduces the need for soybean meal and therefore the cost (Subsuban et al., 1990). Similarly, in an experiment with finisher pigs, less soybean meal was needed to maximize performance in diets based on QPM compared with diets having maize. Beef steers fed on high–lysine maize gained faster weight compared to those fed on normal maize. Thus, QPM can reduce the cost of animal feed by decreasing the expenditure incurred on more expensive high protein sources. Linear programming models allow feed companies to identify the cheapest way of providing the minimum dietary requirements for farm stock. Calculations for pig and poultry ration containing maize, QPM, sorghum, soybeans meal and synthetic lysine and tryptophan showed that the usage of QPM instead of maize resulted in saving of 2.8% on chickens feed and 3.4 % on pig feed (Lopez - Pereira, 1992). It is also evident that if QPM was to replace maize in broiler feed in Kenya, the 5% cost reduction would translate into a gain of US dollars 300,000 either as reduced costs for farmers or profit for feed manufactures. In India also it can happen if we use QPM as an ingredient in animal feed. It will help in reducing the cost of feed as well as in increase the growth of the animal either it is broiler, chicken, pig or cattle. The broilers and chickens fed with QPM matured in less time as compared to non QPM fed ones and the farmer benefitted by selling more number of animals in a short span of time. Additionally, QPM fed pigs experience rapid weight gain and are ready for market sooner or can provide an additional quality protein source for small farm families. Impact of QPM Babies and adults consuming QPM are healthier and at lower risk for malnutrition disorders such as marasmus and kwashiorkor. Data from Latin America and Africa showed the role of QPM in reversing the effects of malnutrition in those who are already affected. QPM offers 90% the nutritional value of skim milk, the standard for adequate nutrition value. At a time when UNICEF reports that 1,000,000 infants and small children are starving each month, the inclusion of QPM in daily rations improves health and saves lives. Additionally, QPM fed pigs experience rapid weight gain and are ready for market sooner or can provide an additional quality protein source for small farm families. The commercial success of QPM can be achieved as several QPM hybrids have been developed and tested across varying climatic and growing conditions. At present QPM varieties are grown on roughly 9 million acres (36,000 km²) worldwide. Meanwhile, QPM research and development have spread from Mexico to Latin America, Africa, Europe, and Asia. In Guizhou, the poorest province in China, where QPM hybrid yields are 10% higher than those of other hybrids, and the crop has enabled new pig production enterprises, bringing increased food security and disposable income. In total, the QPM germplasm is being grown worldwide and it is contributing over $1 billion annually to the economies of developing countries. Production requirements Isolation distance The foremost requirement for QPM cultivation is isolation distance of minimum 400 meters. There should not be any other maize crop (non - QPM) in surrounding of 400 meters. The opaque - 2 gene is expressed when it present in homozygous conditions, if any other maize crop is there in surrounding area and pollen of other maize will fall on QPM silk and it will create heterozygous conditions resulting opaque 2 gene will not express that is why it is strongly recommended that we will have to grow QPM crop in isolation or we can grow this in a specified area where only QPM is grown. Soil and climate QPM can be grown successfully in a wide range of soil from loamy sand to clay. But it performs well in high organic matter content soil with high water holding capacity and neutral in pH. Soil should have high drainage capacity as maize is more susceptible to water logging condition. QPM can be successfully grown in varied climatic conditions though out the country in an altitude from mean sea level to 3000 m height. Selection of cultivar A no. of QPM hybrids have been released in India for cultivation namely, HQPM1, HQPM 4, HQPM 5, HQPM 7, Shaktiman 1, Shaktiman 2, Shaktiman 3, Shaktiman 4, Shaktiman 5, Pusa HM 8, Pusa HM 9, Vivek QPM 9 and Pusa Vivek QPM 9 improved. The farmers can select anyone among these hybrids in consultation with local maize breeder/agriculture expert. Sowing time QPM can be grown in all the seasons viz. kharif, rabi and spring. Seed rate Seed rate varied according to seed size, season, sowing method. But on an average 20 kg/ha is optimum for higher yield. Seed treatment To protect the seed from seed and soil borne diseases and pest seed should be treated before sowing with fungicide Bavistin + Captan in 1:1 ratio @ 2 g/kg seed. Method of sowing Line sowing in furrows at 60 - 70 x 20 - 25 cm (row x plant) spacing to obtain the optimum plant population of 70000 to 80000 per ha with sowing depth of 4 - 5 cm is the best method. Nutrient management The requirement of nutrient and fertilizers are as follows: Nutrient Dose Form Requirement (Kg/ha) N 150 - 180 Urea 3255 - 3906 P2O5 70 - 80 SSP 438 - 500 K2O 70 - 80 MOP 116 - 133 Besides that ZnSO4 @ 25 kg/ha and FYM @ 10 t/ha is required for high productivity of QPM. FYM should be applied at 10 - 15 days before sowing. The whole amount of SSP, MOP, ZnSO4 and 10% of urea should apply as basal in furrows. The remaining urea should be applied in three split applications. 20% urea at 4 leaf stage, 40% at 8 leaf stage and remaining 30% at flowering stage. Fertilizers should be applied from both sides of rows. Three days before application of fertilizers light hoeing is needed for optimum use of nutrients by crops. Water management If irrigation facility is available then irrigation should be done in furrows up to 2/3rd height of the ridge at knee high stage, flowering and grain filling stage. Weed management Weed is a serious problem of maize in Tirap district of Arunachal Pradesh which may causes yield loss up to 35%. Therefore, timely weed management is essential for good yield. Pre - emergence herbicide atrazine @ 1.0 - 1.5 kg a.i./ha in 600 litre water is very effective for control of weed. Tembotrione @ 262 ml in 375 litre water is recommended for post - emergence application and it should be applied when the crop is 25 - 30 days old. Earthing up Earthing up is a very essential operation in QPM cultivation. Earthing up should be done when the crop is 35 - 40 days old. Insect Pest Management: Maize stem borer (Chilo partellus) The pest lays eggs on the lower surface of central whorl leaf and the larvae enter the plant from the central whorl and eventually results in dead heat formation Foliar application of Chlorantraniliprole 18.5 SC @ 0.3 ml / litre water in 200 litre water per ha is quite effective The spray should be done at the appearance of symptoms on 2 - 3 weeks old crop. It can also be controlled by release of 8 trico cards (Trichogramma chilonis) per ha at 10 & 17days after germination. Pink stem borer (Sesamia inferens) This insect is more serious in peninsular India during rabi season. Foliar application of Chlorantraniliprole 18.5 SC @ 0.3 ml / litre water in 200 litre water per ha is quite effective. The spray should be done at the appearance of symptoms on 2 - 3 weeks old crop. Shoot fly (Atherigona spp.) It is more serious during spring season in northern India. It lays eggs on emerging seedlings and maggets cuts the growing point resulting in dead heart formation. Seed treatment gaucho 600FS @ 6.0 ml/ kg seed is most effective. Fall Armyworm (Spodoptera frugiperda) It is new exotic pest in maize ecosystem. It feeds heavily on central whorl leaves and it is more serious on crop up to six weeks old. It lays eggs in clusters on upper and lower surface of the leaves. Young larvae cause papery windows on leaves while grown larvae feeds by making bigger irregular wholes, cut the leaf margins and may damage the central whorl leaves also. The infected plants are filled with its excreta. The seed treatment with Cyantraniliprole 19.8% + Thiamethoxam 19.8% FS @ 6 ml/kg of seed offers protection for 15 - 20 days of crop growth against Fall Armyworm is quite effective up to 3 leaves/ 20 days old crop. Release of egg parasitoids viz., Telenomus remus (4000/ ac) or Trichogramma pretiosum @ 50,000/acre at 7 and 14 days following first spray using neem formulation with the trap catch of one moth/day observed continuously. Note: Parasitoid release may be alternated with neem spray at weekly intervals, but not to be applied simultaneously. For management of early instar larvae with a damage level of 5 - 10%, whorl application of Bacillus thuringiensis v. kurstaki formulations 2% (400g/acre) applied @ 2g/l or Metarhizium anisopliae or Beauveria bassiana (1kg/acre) applied @ 5 g/liter is recommended. If infestation is more than 10%, spray with anyone of the recommended insecticides with label claim, viz., Chlorantraniliprole 18.5 SC (80 ml/acre) applied @ 0.4 ml/l or Thiamethoxam 12.6 % + Lambda cyhalothrin 9.5% ZC (50ml/acre) applied @ 0.25 ml/l or Spinetoram 11.7 % SC (100ml/acre) applied @ 0.5 ml/l is recommended. DISEASE MANAGEMENT Turcicum leaf blight: Spray Zineb/Meneb @ 2.5 - 4.0 g/l water 2 - 4 times at 8 - 10 days intervals as a control measure. Maydis leaf blight: It can be controlled by 2 - 4 times spraying of Dithane Z - 75 or Zineb @ 2.4 - 4.0 g/l water at 8 - 10 days intervals after first appearance of the symptoms of disease. Banded leaf and sheath blight: Seed treatment of peat - based formulation (Pseudomonas fluorescence) @ 16 g/kg of seed or soil application @ 7 g/l water as soil drenching or foliar spray of Sheethmar (Validamycin) @ 2.7 ml/l water is effective against this disease. Bird management In some places mature cobs are damaged by birds. In such situations matured cob can be protected from bird damage by tying cobs with leaf of the same plant. Harvesting Harvesting should be done at optimum moisture content (20%) in grain to avoid postharvest loses due to store grain pest and diseases. Harvesting immediately after shower should be avoided. The harvested cobs should be sun dried before shelling and should be shelled at 13 - 14% grain moisture. During storage the moisture content of grain should be 8 - 10 %. Table 1. Essential amino acid content of maize Amino acid Normal (mg per g N) QPM (mg per g N) Lysine Isoleucine Leucine Sulphur amino acid Aromatic amino acid Threonine Tryptophan Valine 177 206 827 188 505 213 35 292 256 193 507 188 502 199 78 298 Table 2. Protein quality of maize Quality measures Normal QPM True protein digestibility Biological value (%) Amount needed for equilibrium 8040 - 47547 92 80 230 References Gunarathna NS, De Groote H, Nestel P, Pixley KV and McCabe GP. (2010). A meta - Analysis of community level studies on quality protein maize. Food Policy. 35: 202 - 210. Krivanek AF, De Groote H, Guraratna NS, Diallo AO and Friesen D. (2007). Breeding and Disseminating quality protein maize (QPM) for Africa. African J. Biotech. 6 (4):312 - 324. 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