White Maize Hybrids Research Articles

Development of high-amylose maize (Zea mays L.) genotypes adapted to Indian conditions through molecular breeding

Context Amylose is a type of resistant starch with numerous health benefits and industrial applications. Starch from maize (Zea mays L.) usually has an amylose content of ~25%. Aims The aim was to develop high-amylose maize genotypes suitable for human consumption and adapted to Indian conditions. Methods Marker-assisted backcross breeding was used to transfer the mutant ae1 allele from a high-amylose donor from the USA into the three parents (HKI 1344, HKI 1378, HKI 1348-6-2) of two high-yielding white maize hybrids (HM5 and HM12) grown in India. Key results In converted lines, amylose content was 40.40–58.10% of total kernel starch, compared with 22.25–26.39% in parents. The percentage increase in amylose content was 63.70–153.03%. There was a significant amount of background recovery in each backcross generation: 66.80–79% in BC1F1, 72.85–88.60% in BC2F1, and 84.45–93.70% in BC2F2. Overall, the total kernel starch content was reduced (by ~22%) in the ae1-introgressed families. Conclusions The converted lines developed in the study are enriched with kernel amylose while showing significant background recovery. Implications The high-amylose lines developed may be highly beneficial for diabetic patients and in the bioplastics industry, and should be suitable for growing under Indian conditions.

Development of high-yielding white maize hybrids with better chapatti-making quality compared to traditionally used local landraces.

The present research focuses on the chapatti making quality of high-yielding white maize hybrids compared to available low-yielding local yellow and white landraces in India. In this study, the top nine superior hybrids were selected for testing the physical properties of the maize kernels, proximate composition of flours and chapattis, physical parameters of chapatti, textural properties, sensory evaluation of chapattis and pasting properties of maize flour. The results revealed the superiority of white maize hybrids (WMH), viz., WHM 1, WHM 2, and WHM 8 over the local yellow and white landraces for most of the parameters studied. In sensory analysis, though, the yellow landrace was considered superior by the panellists in terms of colour but the white maize hybrids outperformed in overall sensory analysis and were more acceptable than the yellow and white maize landraces. These high yielding white maize hybrids with good consumer acceptance may cater for the needs of rural and tribal populations in India who prefer white maize as a staple food.

Genetic diversity analysis and heterotic grouping of Indian white maize inbred lines using combining ability and SNP markers

AbstractMaize (Zea mays L.) is a versatile crop with high genetic yield potential and various uses. While yellow maize is primarily used for animal feed, white maize is preferred as a food by rural and tribal populations in India. However, white maize landraces suffer immensely in terms of low yield. Heterotic grouping is an excellent method to develop hybrids with increased yield potential in maize. The heterotic grouping of 78 white maize inbred lines was performed using combining ability and molecular diversity analysis. The lines were crossed with two testers, and the resulting hybrids were evaluated for grain yield at three locations representing different agroecological zones in India. The combining ability analysis based on specific combining ability effects on mean grain yield was used to classify the inbred lines into heterotic groups (HG‐A: 18 inbreds; HG‐B: 33 inbreds). Additionally, marker‐based clustering using 62,470 single nucleotide polymorphisms (SNPs) generated through genotyping by sequencing was also employed to determine the genetic relationships among these lines. The combining ability information was superimposed on marker‐based clustering data to obtain the heterotic grouping information, and two distinct HGs with 7 (HG‐1) and 18 inbred lines (HG‐2) were developed. The results of this study will contribute to the development of high‐performing white maize hybrids through the efficient utilization of clear‐cut and well‐defined HGs. Hence, the use of SNP markers along with the combining ability of inbred lines is a useful method for heterotic grouping and understanding of genetic relationships of white maize.

Effects of planting date, environments and their interaction on grain yield and quality traits of maize hybrids

Maize is one of the most important staple food crops for most low-income households in the Southern African region. Erratic and inconsistent rainfall distribution across maize-growing areas is a major threat to maize production. Late rains in recent years have forced farmers to plant later than the optimal planting dates, leading to poor maize quality being reported by industry, which raised the question of the influence of later planting dates on grain yield and quality traits of maize. Three yellow and three white maize hybrids were evaluated at three planting dates in three different production environments for three consecutive seasons using a randomized complete block design with three replications. The second and third planting dates caused a significant yield decrease of 23.37 % and 53.73 % from the first planting date across environments, respectively. Planting date three was associated with decreased grain yield, starch content, and increased protein but no significant change in fat and fiber content. Some hybrids yielded relatively well at all planting dates. In conclusion, the early planting date was the most suitable for maize grain yield and starch production in the maize-growing areas of the country. However, planting in January should be avoided at all costs, as it leads to very low yield and poor grain quality.

ESTIMATION OF MAIZE GENETIC COEFFICIENTS FOR THE CERES-MAIZE MODEL USING NON-DESTRUCTIVE METHODS

The Crop Environment Resource Synthesis-Maize (CERES-Maize) mechanistic model, included in the Decision Support System for Agrotechnology Transfer (DSSAT), is a useful and powerful tool that simulates the growth and yield of maize in different environments. The qualitative and quantitative information provided to the CERES-Maize model guarantees reliability in the simulations obtained. However, it requires a lot of information such as soil characteristics, daily climate, crop characteristics and management, as well as six genetic coefficients. This research assessed a non-destructive methodology for estimating the six required parameters (genetic coefficients): P1, P2, P5, G2, G3 and PHINT, based on the maize physiology, measured from the Growing Degree Days (GDD) base 10. An experiment was established at the experimental station of the International Maize and Wheat Improvement Center (CIMMYT) in Tlaltizapan, Morelos, Mexico, where 27 white maize hybrids and 14 yellow maize hybrids were manually sown in an irrigation conservation tillage system. Once the simulations of maize growth and yield were obtained with CERES-Maize model, the genetic coefficients were calibrated using the Generalized Likelihood Uncertainty Estimation (GLUE). After calibration of the six genetic coefficients for all hybrids, an average values of P1, G2 and G3 were within the typical range, while P2 and P5 were greater than the typical range, and PHINT was below typical range. However, the simulation model showed good performance after calibration, according to the average R2 of 0.9809 and 0.9730 between measured and simulated yields for white and yellow hybrids respectively. The coefficients estimated in this study can be used in the CERES-Maize model to simulate maize yields in different regions of the country for the hybrids used here.

WATER AND AGRONOMIC EVALUATION OF MAIZE HYBRIDS IN RESPONSE TO DIFFERENT ENVIRONMENTS AND NITROGEN DOSES

To achieve water and food safety, it is necessary to identify crops outstanding in regard to efficient water use. In Mexico, the Valles Altos region has frequent water scarcity, so it is necessary to characterize maize genotypes that show outstanding traits under conditions of low water availability. The objective of this study was to identify water productivity, yield and hectolitre weight of white maize hybrids grown in Valles Altos. Ten white maize hybrids were used in the experiment; five from UNAM and five from INIFAP. These hybrids were established under two levels of nitrogen fertilization (low: 80 kg ha-1 and high 160 kg ha-1) in two environments: FESC-UNAM (Cuautitlán Izcalli) and CEVAMEX (Texcoco) in the State of Mexico. The experiment was established as randomized complete blocks, variables were recorded to calculate grain yield at 14 % commercial moisture and related to the volume of water entering each environment, the total water productivity was identified. Statistical analysis was performed with SAS and means were compared with Tukey’s test. With a combined analysis, a significant interaction of environment with hybrids and nitrogen fertilization was found in grain yield. Total water productivity, estimated at an overall mean of 0.78 kg m-3, was significant for environments, hybrids and nitrogen dosage. Grain yield showed an overall average of 4.8 Mg ha-1. In hectolitre weight, a significant difference was found in the environment and hybrid factors, with an overall average of 73.8 kg hL-1. Total water productivity was higher in the FESC-UNAM environment where irrigation was not provided, with no significant difference in grain yield.

Field Performance of Three-way Cross Yellow and White Maize Hybrids in Nepal

Maize hybrids can increase production, bridge the yield gap, and boost up domestic production in Nepal. Three-way cross hybrid introduces an alternative to produce low cost hybrid seed for resource poor farmers. A study was performed to identify promising yellow and white maize hybrids developed by International Centre for Maize and Wheat Improvement (CIMMYT), Mexico in Rampur, Nepal. Nineteen three-way cross white maize hybrids with two checks and seventeen yellow maize hybrids with one check were tested in field experiments on 2017 and 2018. Treatments were replicated twice in α-lattice design with each experimental plot of 9.6-m2 (4-m × 2.4-m). AF17A-426-13/14, AF17A-426-1/2, AF17A-426-28/39, and AF17A-426-15/16 were the three-way cross white hybrids produced grain yield of more than 9000 kg ha-1. Similarly, AF17A-473-20/29 and AF17A-473-18/27 yielded about 9000 kg ha-1 among the three-way cross yellow maize hybrids. These hybrids have commercial potentials to increase maize yield in Nepal if the provided parents are successful in the seed production.

Regulation of Na+ and K+ Transport and Oxidative Stress Mitigation Reveal Differential Salt Tolerance of Two Egyptian Maize (Zea mays L.) Hybrids at the Seedling Stage

Maize is sensitive to salinity stress, which has adverse effects on plant growth and yield. In this study, two Egyptian white maize hybrids, single cross 131 (SC131) and single cross 132 (SC132), were exposed to 100 mM NaCl stress for 12 days in a hydroponic culture and physiological and biochemical parameters, and gene expression for some Na+ and K+ transporters were evaluated. The results revealed that the total dry weight of SC131 was greater than that of SC132. The root growth was also better for SC131 than SC132. The Na+ concentration in leaves and stems, and H2O2 were significantly lower in SC131 than in SC132, while the proline concentration was higher in the leaf of SC131 than in SC132 under salt stress. Moreover, catalase and ascorbate peroxidase activities increased with salinity in SC131 leaves compared to catalase and GR in SC132. Salt stress slightly induced the expression of ZmHKT1;5 (for Na+ exclusion) in SC132, but repressed it in SC131. On the other hand, the expression of ZmHKT2 gene (for K+ exclusion) was highly induced by salt stress in SC132, but was not detected in SC131. The salt increased the expression of ZmNHX1 (for vacuolar Na+ sequestration) in SC132, but repressed it in SC131. Taken together, these results suggest that the maize hybrid SC131 is more tolerant to salinity than SC132, thanks to a more efficient leaf Na+ exclusion mechanism, that is yet to be investigated, and to a better antioxidant defense system. Thus, SC131 could constitute a new hybrid worthy of consideration in maize breeding programs for enhanced productivity on salt-affected soils.

EFFECT OF PLANTING DATE ON GROWING DEGREE DAYS, GROWTH AND PRODUCTIVITY OF SOME MAIZE HYBRIDS

Two field experiments were carried out at the Experimental Farm of Agricultural Research Center, Egypt, to investigate the effect of different sowing dates (May 15, June 1 and June 15) on the vegetative growth, flowering traits, growing degree days, yield and grain quality of some white maize hybrids (S.C 10, S.C 128, S.C 131, S.C 2031, T.W.C 321, T.W.C 324 and T.W.C 329) during 2017 and 2018 seasons. The results obtained could be summarized as follows: 1- The results indicated that early planting surpassed the other planting dates in most growth characters (number of leaves/ plant, leaf area/ plant, stem, leaves and shoot dry weight/plant), photosynthetic pigment (total chlorophyll), physiological parameters (crop growth rate, relative growth rate and net assimilation rate), flowering characters (days to tasseling, silking and maturity), yield (plant height, ear height, ear length, ear diameter, number of rows / main ear, number of grains / row, grains weight/ ear, grain yield/fed, stover and biological yields/fed and harvest index) and grain quality (oil and protein %) in both seasons. 2- There are significant differences among the tested hybrids in most characters studied. S.C 2031 hybrid was generally superior to the other hybrids in all growth characters, chlorophyll content, yield (number of ears/plant, 100-grain weight, grain weight/ear and grain yield/fed) and protein percent in grains. However, S.C 131 and S.C 128 hybrids produced generally the highest values of days to maturity, ear diameter, stover and biological yields/fed and oil percent in grains. 3- The interactions between sowing dates and maize hybrids were found to be significant for most characters under study. It could be concluded that planting S.C 2031 hybrid which the best hybrid under early planting (May 15) condition, while S.C 131 hybrid showed the best performance under mid planting (June 1) condition compared to other hybrids. However, T.W.C 321 exhibited the maximum grain yield /fed under the late planting (June 15) in comparison with other hybrids under the environmental conditions of this experiment.

PERFORMANCE OF MAIZE CROSSES UNDER LATE PLANTING CONDITION

A field experiment was carried out to evaluate the performance of seven white maize hybrids under late planting condition with respect to yield and grain quality during the two successive seasons of 2017 and 2018. The experimental design was laid out using randomized complete block design with four replicates. Maize hybrids were significantly differed in all traits studied in both seasons, except grain oil percentage. The variety S.C 128 exhibited the highest days to maturity, while the lowest ones was T.W.C 321 in both seasons as compared with other tested hybrids. The variety T.W.C 321 significantly surpassed other tested hybrids in mean values of grain yield /fed and relative grain yielding ability, while T.W.C 324 and T.W.C 329 gave the lowest mean values in both seasons. Concerning grain quality, S.C 131 and S.C 2031 recorded the highest mean values of oil yield/fed, Meanwhile, T.W.C 321 and S.C 2031 surpassed the other hybrids in mean values of protein percentage and protein yield/fed in the both seasons. It could be summarized that the best hybrid was T.W.C 321 when planting maize in late sowing, where it produced grain yield more than other S.C 131, S.C 2031, S.C 10, S.C 128, T.W.C 324 and T.W.C 329 hybrids by 2.74, 3.08, 4.85, 4.89, 21.40 and 24.96%, respectively as an average of both seasons.

Response of white maize hybrids to plant densities and nitrogen fertilizer rates

Two field experiments were conducted on the Farm of Agric. Res. and Exp. Center of Fac. of Agric. Moshtohor, Benha University, Toukh Directorate, Qalyubia Governorate, Egypt, during the two successive summer growing seasons of 2016 and 2017 to study the effect of three plant population densities i.e. 20000, 24000 and 28000 plants/feddan (fed) and three nitrogen fertilizer rates, i.e. 90, 120 and 150 kg N/fed on the growth traits, yield components, yield and some kernels chemical properties of three white single cross hybrids of maize (S.C. 7071, S.C. 30K8 and S.C. 2031). The obvious results of this investigation can be summarized as follows: Increasing plant population density from 20000 to 28000 plants/fed significantly increased mean values of No. of days from planting to 50 % tasseling and silking, leaf area index, plant height (cm), ear height (cm) No. of barren plants/fed, No. of ears/fed, stover yield/fed (kg) and biological yield/fed (kg) in both seasons. On the other hand, mean values of No. of green leaves/plant, leaf area/plant (cm2), No. of plants carried two ears/fed, No. of kernels/ear, ear weight (g), shelling (%), 100-kernel weight (g), ear yield/fed (kg), grain yield/fed (kg), harvest index, nitrogen uptake/fed (kg) and protein yield/fed (kg) were significantly decreased in the two seasons. Allmost traits of maize under study were significantly increased by increasing nitrogen fertilizer rates from 90 and 120 to 150 kg N/fed except, No. of days to 50 % tasseling and silking as well as No. of barren plants/fed were significantly decreased with increasing nitrogen rates in the both seasons, nitrogen fertilizer rate of 150 gave the best mean values for all maize traits under study. White single cross hybrids of maize were significantly differed in all maize traits under study in the both seasons. Maize hybrid of S.C. 30K8 was significantly surpassed S.C. 7071 and S.C. 2031 in mean values of No. of plants carried two ears/fed, No. of ears/fed, No. of kernels/ear, grain yield/fed and harvest index as well as gave the lowest mean values of No. of barren plants/fed and the shortest period from planting to 50 % tasseling or silking in the both seasons. Moreover, S.C. 2031 surpassed the other two maize hybrids in mean values of leaf area/plant, leaf area index, ear weight, 100-kernel weight, ear yield/fed, biological yield/fed, nitrogen uptake/fed and protein yield/fed in the two seasons. Meanwhile, S.C. 7071 recorded the highest mean values of No. of green leaves/plant, plant height, ear height, shelling % and stover yield/fed in the two seasons. The first order interactions between (20000 plants/fed X 150 kg N/fed), (24000 plants/fed X S.C. 30K8), (20000 plants/fed X S.C. 2031) and (150 kg N/fed X S.C. 30K8) as well as the second order interactions between (24000 plants/fed X 150 kg N/fed X S.C. 30K8) and (20000 plants/fed X 150 kg N/fed X S.C. 2031) were significantly recorded the greatest grain yield/fed as compared with the others interactions in the both seasons.

Physical, chemical and wet‐milling properties of commercial white maize hybrids cultivated in México

Physical, chemical and wet‐milling properties of commercial white maize hybrids cultivated in México

Yield and yield attributes of two exotic white maize hybrids at different agroclimatic regions of Bangladesh under varying fertilizer doses

Yield and yield attributes of two exotic white maize hybrids at different agroclimatic regions of Bangladesh under varying fertilizer doses

Physiological and chemical characteristics of cultivated single cross maize (Zea mays L.) hybrids

Maize is the principle agricultural crop, considered the third important cereal crop in terms of its great economic importance as constitutes 70% of human food and animal fodder. So far, maize becomes crucial for starch, fructose and oil industries. Several maize breeding programs developed number of withstanding commercial hybrids against many diseases and characterized by high yield production. As hybrids vigor is dependent on transferring assimilates from vegetative to reproductive parts, this study is focused on evaluating some metabolic and chemical parameters of three derived hybrids from the hybridization process. Mineral content, total soluble sugars and total protein were measured in the dry materials of the single cross white maize hybrids (Sc 10, Sc 125 and Sc 132). Sc 10 was superior in Ca, Cu and Zn content, Sc 125 had enclosed higher K content whereas Sc 132 contained the highest amounts of Fe and Si. Total sugars and protein contents have differed between the hybrids. Stalk strength which maintained by normal cellulose synthesis and deposit on the walls has also differed in amount among the hybrids. GC-MS analysis revealed the presence of 14 hydrocarbon species most of which have biological activities as antioxidants and anticancer. Similarity of the chemical profile and the hydrocarbon content was observed between Sc 10 and Sc 125 hybrid due to their common father \'Sd 7\'. This study provides aspects standing beyond the vigorous hybrid and suggests that investigation of the physiological and chemical components of hybrids after each hybridization process is as important as studying the vegetative and yield characters.

Grain Quality Within ex situ and in situ Conserved Traditional White Maize Landraces

White maize had an important role in human nutrition throughout the Western Balkan region. A great number of farmers (approximately 86% in Serbia) still grow traditional white Open Pollinated Varieties (OPVs) for human diet. Out of 2217 maize landraces stored within Maize Research Institute „Zemun Polje” (MRIZP) gene bank, more than 700 are white kernel accessions. Eighteen white maize landraces, collected in the Western Balkan region in different periods, were selected for the present study. By the evaluation of agromorphological performances and the basic chemical composition of grain, the objective was to determine the importance of landraces conserved under in situ and ex situ conditions, to be used as the initial material for breeding. The idea was to determine whether the varieties conserved under ex situ conditions (collected from the same or different regions) distinguish from varieties permanently grown in the region of western Serbia. It was found that varieties permanently grown in the western Serbia were more similar to varieties of the ex situ collection from eastern Bosnia and Herzegovina than to varieties collected in western Serbia 50 years ago. The comparison between OPVs and modern white maize hybrids for the basic chemical composition of grain showed the significant potential of OPVs for nutritive grain quality improvement. Increased organic production creates new possibilities for more intensive incorporation of OPVs into this agricultural system. New opportunities for the cooperation and share of responsibilities among breeders, farmers and genetic resources managers are initiated, to be used for in situ maize genetic resources conservation improvement. More detailed characterisation and evaluation of the white maize landraces will offer an explanation of what has motivated our farmers to maintain the OPVs production through centuries, despite the availability of modern hybrids.

Grain Yield and Stability of White Early Maize Hybrids in the Highland Valleys of Mexico

There is great interest in Mexico in reducing imports of grain and becoming self‐sufficient in cereal production. Identifying high‐yielding and stable maize (Zea mays L.) hybrids from different research institutions could contribute to increasing maize production in the highlands of Mexico. In this study, 16 early white maize hybrids were evaluated at 37 highland sites in several Mexican states with the objective of identifying high‐yielding and stable hybrids, as well as high‐yielding sites. Using the site regression model, it was possible to identify some outstanding hybrids (CHLHW09035, CHLHW02517, and HIBRIDO 2010) with acceptable grain yield production that were also stable across most of the 37 sites. Hybrids ST‐010 and ASPROS‐823 were less stable but produced acceptable yields. Sites with higher stability included Site 26 (Amealco, Queretaro), Site 7 (Epitacio Huerta, Michoacan), Site 37 (Tlachaloya, State of Mexico), Site 34 (Ciudad Hidalgo, Michoacan), and Site 29 (Metepec, State of Mexico). Other sites with satisfactory stability included Site 20 (Jilotepec, State of Mexico), Site 5 (Quecholac, Puebla), Site 6 (Huejotzingo, Puebla), Site 13 (Ajacuba, Hidalgo), and Site 19 (Santo Domingo, Oaxaca).

Evaluation of combining ability in white corn for special use as corn grits

Abstract To assess the genetic potential of white corn for corn grits, 28 hybrids resulting from diallel crosses of eight parents, including parents and S1 generations, were evaluated. The combining abilities and levels of heterosis and inbreeding depression were estimated. The parents used were the main white maize hybrids of the Brazilian germplasm. The combinations HT 9332 x HT 392, IAC Nelore x HT 9332, IAC Nelore x HT 932, and IPR 119 x IAC Nelore are promising for reciprocal recurrent selection programs targeting higher grain yield. Hybrid IPR 127 was indicated as a source of industrial lines with favorable traits for dry-rolled corn production. Hybrid IAC Nelore had the lowest estimate of inbreeding depression and was recommended for the breeding of lines and participation in higher-yielding hybrids and composites.

Bacillus cereus sensu lato strain B25 controls maize stalk and ear rot in Sinaloa, Mexico

Fungal pathogens causing maize stalk and ear rot are a potential threat to grain production in regions where monoculture extensions can reach over 500,000ha per year. This particular problem is observed in northern Sinaloa, Mexico with the fungal pathogen Fusarium verticillioides. Three native Bacillus spp. strains isolated from the maize rhizosphere were tested for their potential as biocontrol agents (BCAs) against fusariosis in maize, during the 2011–2012 fall-winter growing season. Based on its performance, the Bacillus cereus sensu lato strain B25 was selected for further analysis. The effectiveness of maize seed inoculation with this strain was examined in two more consecutive growing seasons. The potential for B25 to control Fusarium stalk rot (FSR) and Fusarium ear rot (FER) of maize, as well as the accumulation of fumonisins in kernels, was thus assessed with white maize hybrids grown under different field conditions in northern Sinaloa, Mexico. FSR and FER incidence and severity were substantially reduced as compared to controls in all trials conducted. Fumonisin contamination in maize grains was also reduced (up to 93.9%) by B25 application, as compared to the control. Furthermore, B25 significantly increased grain yield in several trial sites or crop seasons, above the average of the untreated controls and consistently above the average of F. verticillioides-inoculated controls. Based on these findings, we propose that seed bacterization with strain B25, combined with adequate crop management practices, may become a useful tool for avoiding Fusarium stalk and ear rot of maize. This practice will also provide safe fumonisin grain levels for maize production in northern Sinaloa.

Maize (Zea mays L.) Genetic Factors for Preventing Fumonisin Contamination

Fusarium moniliforme and Fusarium proliferatum are the most frequently isolated fungi from maize (Zea mays L.) in Spain. Both Fusarium species produce toxins potentially dangerous for animals and humans, the fumonisins being the most significant of those toxins. White maize is preferred for human consumption, and extra care should be taken to avoid kernel mycotoxin contamination. The objectives of this study were to identify and quantify kernel infection by Fusarium spp. and contamination by fumonisin on white maize hybrids, to search for white maize sources of resistance to infection by Fusarium spp. and mycotoxin contamination, and to preliminarily study the genetics involved in such resistances. Ten F(1) single crosses derived from a diallel mating design among five white maize inbreds were evaluated in a randomized complete block design with three replications in 2002 at two locations. Fusarium verticilloides and F. proliferatum were detected on kernels of white maize hybrids cultivated in northwestern Spain. No differences in fungal infection were found among maize genotypes, but differences in fumonisin contamination were significant and could be related, in part, to differences in husk tightness. Among the genotypes studied, general combining ability (GCA) effects were the most important for resistance to fumonisin contamination. Inbreds EP10 and EC22 showed the most favorable GCA effects for husk tightness and fumonisin content, and the cross between them, EP10 x EC22, had the most favorable specific combining ability (SCA) effect for husk tightness. Inbreds EP10 and EC22 showed favorable GCA effects for fumonisin contamination and husk tightness, and the cross EP10 x EC22 was the only one with an average fumonisin level below 1 mug/g. Although this should be confirmed with more extensive studies, white maize inbreds developed from white maize landraces could be sources of resistance to fumonisin contamination.

Resistance of South African maize hybrids to maize streak virus

Data from maize cultivar trials at Vaalharts over a five-year period were used to evaluate the level of resistance to maize streak virus (MSV) in commercial maize hybrids, and to determine the potential value of such resistance. Maize hybrids presently grown in South Africa showed varying degrees of resistance to MSV. In general, yellow maize hybrids displayed a wide range of genetic variability, from resistant to highly susceptible, whereas white maize hybrids were mostly highly susceptible. Calculated resistance indices on a scale from 1 (resistant) to 5 (highly susceptible) proved very useful in quantifying genetically-based plant reaction to MSV infection.