Advances in Maize Science

Botany, Production, and Crop Improvement

Ratikanta Maiti, Humberto González Rodríguez, Ch. Aruna Kumari, Sameena Begum, Dasari Rajkumar

• Publisher: Apple Academic Press
• Year: 2021
• eBook ISBN: 9781000210682
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

This new volume offers a multi-pronged perspective on maize science, bringing together important recent research advances from several disciplines. The volume covers maize from origin to biotechnology. It provides an overview of recent world maize production along with technological advancements and green strategies in maize science. The authors cover the background of maize, its origin and domestication, ideotypes, botany, taxonomy, physiology of crop growth, methods of cultivation, production, nutritional functions, biotic and abiotic stress impacts, postharvest management and technology, maize grain quality, and advances in breeding and biotechnology, filling a gap in the literature of maize.

CHAPTER 1

Background and Importance of Maize

ABSTRACT

Maize is becoming an ideal staple food owing to its low costs of production and high consumption rates. Additionally, it can be processed into several products which generate an additional source of income for maize farmers, maize processors, and distributors. This chapter presents the importance of maize at the global level and discusses a brief outline of research advances in various aspects of the maize crop.

1.1 IMPORTANCE OF MAIZE

Maize (Zea mays) is commonly referred to as corn. Research evidences indicate that it had its origin in Central Mexico, 7000 years in the past from a wild grass. It has been converted into a good source of food by Native Americans. It is widely grown throughout the world. Some of the major constituents of maize grain are starch (72%), protein (10%), and fat (4%). This cereal has a capacity of supplying energy of approximately 365 Kcal/100 g. The top most maize producing countries are the United States, China, and Brazil, which produce around 563 of the 717 million metric tons/year. Maize can easily be processed into a multiplicity of food and industrial products. Some of the commonly used products are starch, sweeteners, oil, beverages, glue, industrial alcohol, and fuel ethanol In the preceding 10 years, its use for the production of fuel has considerably increased. This fuel production in the United States accounts to 40% of the maize production where most of the maize grain produced is used in the production of ethanol Thus, the ethanol industry has a larger share of maize requirement. It has also its utility for animal and poultry feed because of its demand and competition, higher prices for maize may increase this demand competition. Maize is becoming an ideal staple food owing to its low costs of production and high consumption rates particularly by people suffering from micronutrient deficiencies and health problems (Ranum et al., 2014).

Types of maize/corn

Flint corn: This is a variant of maize, which has a hard outer layer and low water content. It is multicolored and is utilized for decorations in the United States.

Dent corn: Dent corn has high soft starch content and is commercially cultivated for grain and fodder.

Pod corn: Also known as wild maize is the most primitive variety of maize and recognized best as the progenitor of corn.

Popcorn: A variant of corn that swells and puffs on heating. When heated, the kernel ruptures and permits the kernel content to expand, cool, and finally set into popcorn.

Flour corn: Flour corn has a soft endosperm and utilized mainly to prepare corn flour.

Sweet corn: Sweet corn has a high sugar content and is generally considered a vegetable. Sweet corn is best when consumed fresh or canned to preserve its freshness (Farm rowdy).

Economic Importance

Maize is a rich source of vitamins, minerals, and dietary fiber. As many small-scale farmers are engaged in maize farming, it makes it a cheap source of vitamins and minerals for rural people. Maize can be processed into several products which generate an additional source of income for maize farmers, maize processors, and distributors. Some of the processed products that can be made from maize comprise:

• Corn Starch: Is utilized as a thickener for liquid food, is the key ingredient in biodegradable plastic, a component that can be utilized to substitute talc in body powder, and is also applied by dry cleaners to maintain clothes firm.
• Oil: Oil obtained by squeezing the corn germ is mostly used to prepare crunchy, sweet popcorns. Further, it can be utilized to produce margarine and in the making of soap, cosmetics, etc.
• Glue: Corn germ can be processed to make industrial glue stronger. This reduces the cost of industrial glue production.
• Ethanol: By distilling corn, an alcohol called ethanol can be produced which can be combined with gasoline and utilized in powering vehicles. Gasoline generally contains ethanol in the ratio 10:90 (10–ethanol, 90–gasoline) to oxygenate the fuel and decrease air pollution. Ethanol is a valuable solvent that can be utilized in domestic products like paints and varnish.
• Ethanol can be used to kill microorganisms and a common ingredient in cosmetics, beauty products, and hand sanitizers. Its capacity to effectually kill microorganisms makes it an excellent

Maize can be cooked, roasted, or blended and utilized in delicacies like fried rice, etc. Blended corn can be utilized for pancakes, baby food, and baking.

Maize can be processed into diverse products and more employment opportunities will be generated. This in turn causes a fall in the cost of purchasing maize and maize products. Because of all these more people will be able to afford good, quality food.

1.2 ETYMOLOGY

The determination of time and path of the maize introduction into West Africa could cast light on primary records about the area. This would assist in clarifying several questions of the indigenous cultures interactions with each other along with intrusive cultures, and it can propose a component of absolute dating into the chronology of archaeological deposits in the area. But, most of the methods for dating archaeological material in absolute terms cannot be used in the study of the ethno history of West Africa. The maize cob was extensively utilized in West Africa as a decorative roulette on pottery, generally on the coarser wares. So, the presence or absence of such decoration was used as a horizon in digging archaeological sites in West Africa. Furthermore, botanists have examined the genetics of maize in West Africa in detail, so that a statistical study of maize imitations on pottery, could allow the identification and relative location in time of variations in the maize population grown at a given site, and thus help to date the pottery (Willett, 1962).

Mexico is the center of domestication and diversity of maize and its ecology has been investigated in Mexico for several decades. Although the wide summaries of diversity and dynamics of native maize populations were identified at the farm and national levels, these topics were not well known at the landscape level. The recent research suggests that apart from environmental factors which are the primary forces influencing the diversity of the species in Mexico, current social origin, such as community of residence or ethnolinguistic group, also affects the maize population structure at more local levels. A landscape viewpoint can help to find out whether these social factors work in a constant manner through diverse environments. Brush and Perales (2007) used the data from the Chiapas Case study to exemplify the role of ethnicity in understanding the maize diversity ecology in Mexico. They found that the environmental variations are significant in ascertaining the general pattern of maize diversity across the Chiapan landscape but social origin has a substantial influence on maize populations in all environments.

Though the correlation between ethnolinguistic diversity and crop diversity has been recorded, much organized study has not concentrated on the role of culture in shaping crop diversity. In this study, Perales et al. (2005) assessed the dispersal of maize (Zea mays) types among communities of two groups, the Tzeltal and Tzotzil. The results indicated that maize populations were separated as stated by ethnolinguistic group. But ethnolinguistic origin-based separation has not been clearly shown by an analysis of isozymes. A reciprocal garden experiment showed that the maize is well adapted to its environment; however, the Tzeltal maize occasionally outyields Tzotzil maize in Tzotzil environments. Due to the closeness of the two groups and selection for yield, it is assumed that the superior maize would dominate both groups’ maize populations, but it was found that such domination is not the case. Thus, in relation to landrace differentiation, they discussed the role of ethnolinguistic diversity in determining social networks and information exchange.

1.3 MAIZE-GROWING ENVIRONMENTS

The conditions in which maize (Zea mays L.) germplasm originated and in which it is assessed can significantly influence outcomes from germplasm assessments, hence affecting where the germplasm will ultimately be utilized. The normally used adaptation classifications such as temperate, tropical, subtropical, and highland are inaccurate. So, Pollak and Corbett (1993) applied multivariate statistical techniques to spatial geographic information system (GIS) datasets of agroclimatic data group from related maize-growing regions in Mexico and Central America. They used these groups to improve the mega-environments developed by CIMMYT maize breeders to help manage their germplasm. On the basis of each year’s monthly data, mean monthly temperatures and precipitation, total precipitation, and mode of the elevations in the grid, the variables such as mean maximum and minimum monthly air temperatures, absolute maximum and minimum air temperatures were analyzed. The cluster analysis was applied on 7 months of growing season data (April through October) to get 25 groups. Then, these 25 groups were categorized into 10 maize ecologies analogous to CIMMYT’s mega-environments. The ecologies comprised three lowlands, three highlands, two subtropical, and two transitional from subtropical to highland. This technique would significantly help in categorizing and utilizing northern Latin America’s large amount of diverse maize germplasm.

Spedding et al. (2004) studied the long-term effect of tillage and residue management on soil microorganisms in a sandy loam to loamy sand soil of southwestern Quebec, by growing maize monoculture. No till, reduced tillage, and conventional tillage with crop residues either taken out from (−R) or retained on (+R) experimental plots were applied as treatments. At two depths viz 0–10 and 10–20 cm, soil microbial biomass carbon (SMB-C), soil microbial biomass nitrogen (SMB-N) and phospholipid fatty acid (PLFA) contents were assessed four times during the growing season. The magnitude of time influence was greater than those accredited to tillage or residue treatments. The SMB-N exhibited a high response to the post-emergence application of mineral nitrogen, whereas SMB-C exhibited insignificant seasonal change (160 μg C g⁻¹ soil) and PLFA analysis has shown a rise in fungi and total PLFA all over the season. PLFA profiles revealed a better difference between sampling time and depth than among treatments. In comparison, the +R plots exhibited a more pronounced residue effect with increased SMB-C (61%) and SMB-N (96%). These findings demonstrated that while evaluating soil quality on the basis of soil microbial components the seasonal variations in soil physical and chemical conditions should be taken into account.

Hirasawa and Hsiao (1999) conducted a study to measure the maize leaf photosynthetic rate over diurnal courses on cloudless days with the leaf held perpendicular to the sunlight.

For the study maize was cultivated in the high-radiation arid summer environment of Davis, California. The maximum leaf photosynthesis was recorded in the late morning on days of high atmospheric vapor pressure deficit (VPD) and then reduced slowly as the day advanced, although the soil was well irrigated. In the measurement chamber when CO₂ concentration was increased to about 1000 μol mol⁻¹, the higher photosynthesis was recorded in the afternoon than in the morning. However, a significant difference was not observed in the curves of photosynthetic rate (A) vs intercellular CO₂ concentration (C_i) for the morning and afternoon. Therefore, photosynthetic capacity was alike for the two periods and there was no proof of photo inhibition by the high photosynthetic photon flux density at noon. Additionally, C_i and photosynthetic rates A quantified over different photon flux densities were lower in the afternoon than in the morning. These results specify that epidermal conductance (mostly stomatal) limits the photosynthetic rates A at noon and early afternoon. On a day with low VPD, midday depression in these results specifies that epidermal conductance (mostly stomatal) limits the photosynthetic rates A and which were not marked for the well-irrigated plants. However, in plants without irrigation and at lower midday water potential the reduction in conductance and photosynthetic rates A was much clearer, initiating late in the morning. Thus, they concluded that the low leaf water potential affected by high transpiration rates causes midday reduction in conductance and photosynthetic rates A.

To decrease agricultural water use in water deficit areas, a study on the response of crop to deficit irrigation is essential. So, to determine the response of maize (Zea mays L.) to deficit irrigation Fané and Faci (2009) conducted two field trials on a loam soil in northeast Spain. All possible combinations of full irrigation or limited irrigation were applied as treatment in the three phases, that is, vegetative, flowering, and grain filling. Then, the interval between irrigations was increased to apply limited irrigation. Water status of soil, crop growth, above-ground biomass, yield, and its component traits were evaluated. Findings revealed that flowering is the most sensitive stage to water scarcity and water deficit at this stage results in higher biomass, yield, and harvest index reductions. Around flowering, treatments with deficit irrigation had significantly lower average grain yield than the well-irrigated treatments and the irrigation water use efficiency (IWUE) was greater in fully irrigated treatments. During the grain filling phase, the deficit irrigation or higher interval between irrigations had no significant effect on crop growth and yield. These results indicate that in maize relatively high yields can be maintained if slight water deficits bring about by increasing the interval between irrigations were restricted to phases other than the flowering stage.

In maize water deficit at tasseling and silking causes significant reductions in grain number. In order to elucidate the causes of reductions in kernel number under the mild stresses typical of humid regions, more information on the responses of crop to water supply is needed. A field experiment was undertaken by Otegui et al. (1995) to measure crop evapotranspiration, E_c, and its association with shoot biomass production, grain yield, and kernel number. To create differences in evaporative demand the experiment was conducted with two sowing dates (6 weeks apart). Then to create a 40-day period of reduced water supply during silking plastic covers were laid on the ground of water-deficit plots. Water deficit affected plant height, maximum leaf area index, and shoot biomass. Shoot biomass accumulation was associated with E_c, but the water-stress treatments had greater water-use efficiencies (WUE). During the treatment period, grain yield was found to be associated to kernels m⁻²(r = 0.88; 6 d.f.), and both grain yield and kernels m⁻² were correlated with E_c. Further, when fresh pollen was applied to late appearing silks, the number of kernels per ear did not increase indicating that ovaries which failed to expose their silks synchronously with pollen shedd...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Abbreviations
• Preface
• 1 Background and Importance of Maize
• 2 World Maize Production
• 3 Origin, Evolution, and Domestication of Maize
• 4 Maize Ideotype
• 5 Maize Botany
• 6 Physiological Basis of Crop Growth and Productivity
• 7 Research Advances in Abiotic Stress Management
• 8 Biotic Stresses Affecting Crop Productivity
• 9 Methods of Cultivation
• 10 Maize Grain Quality Analysis, Food Quality, Chemistry, and Food Processing
• 11 Improvement of Maize: Maize Varieties and Hybrid Maize Technology
• 12 Research Advances in Breeding and Biotechnology of Maize
• Index