CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Maternal genetic inheritance of red pericarp in the grain of maize
Get PDFThe diversity of colors in the grain of corn is wide, from whites to blacks and including a continuum of various shades of yellows, pinks, reds, purples and blues. The most abundant commercial colors are yellow and white, however other colors have become more important because of the presence of pigments to which are attributed favorable effects as a food. The pigments are also considered natural barriers of the grain against the invasion of pests and diseases in the production fields. The colors of the grain of corn occur in three different parts of the seed: the cover of the grain or pericarp, derived from the maternal tissue, with a diploid genetic content; the endo-sperm, including the aleurone layers that are cells in the grain immediately below the pericarp with a chromosome content of 3n; and the embryo, with a genetic content of 2n. The red color considered in this study is present in the pericarp ignoring possible effects in other tissues of grain and other organs of the plant. In this study, we used materials with colorless or red pericarp, and white or yellow endosperm; with the purpose of describing the type of inheritance of this character in the grain of corn. The results indicated a maternal genetic inheritance with classical complete dominance of the red color of pericarp over the clear or transparent phenotype, where the red color of the grains on ear is determined by the genotype of the mother grain but not by the seed embryo genotypes, which is characterized by uniformity of grain color of the ear. This type of inheritance could be useful in the development of pigmented varieties of higher food quality for humans
Traditional farmers’ varieties: a valuable source of genetic variability for biofortification programs
Get PDFSeveral studies underlined the superiority from a nutritional point of view of ancient varieties. In the last years the interest for landraces has been growing, for this reason preservation and valorisation of these genetic sources is very important. In particular these varieties are source of precious genetic variability interesting from a scientific point of view to preserve biodiversity but also for biofortification programs aimed to support small rural communities, where the particular maize germplasm has been developed. In this work we characterized from the nutritional point of view 13 ancient Italian varieties and one coming from Spain (Millo Corvo). In this pre-breeding work we demonstrate the nutritional superiority of ancient varieties if compared with modern hybrids. In particular Spinato di Gandino is the best variety for milling properties and for oil, protein, and total phosphorus content; Storo is the best variety for calorific value and for carotenoids and free phosphorus content. Using these varieties in the next future we will start a bio-fortification program aimed to obtain new populations with improved yields and high nutritional value
Management of southern corn rootworm and leafhoppers by treating seeds: field assessments in maize second crop in Southern Brazil
Get PDFMaize productivity is highly affected by Diabrotica speciosa and Dalbulus maidis in the second crop seasons in southern Brazil. Thus, this study evaluated the effects of different systemic insecticides tested at recommended doses by seed treatment on the management of these two pest species and assessed the influenceof these treatments on maize yield. For this purpose, we conducted a 2-year fieldexperiments (2015/2016 and 2016/2017) at two locations (Chapecó and Guatambú) in Santa Catarina State, southern Brazil. The experiments were conducted under natural infestation of both pest species, with eight treatments [(Imidacloprid, thiamethoxam, imidacloprid+thiodicarb, fiponil, imidacloprid+bifenthrin, chlorantraniliprole, chlorantraniliprole+clothidian (standard used in industrial seed treatment), and a negative control (without insecticides)]. There were fivereplicates per treatment, totaling 40 experimental units. The results showed that seed treatment do not reduce population density of D. maidis after 21 days of plant emergence and injuries in the maize root system caused by D. speciosa larvae. In addition, insecticides via seed treatment do not affect productivity and crop yield components. Regardless of the location and year, root damage was positively correlated with diameter of the firstinternode and inversely correlated with grain yield. This research suggests that maize seed treatments not always provide economic benefits to farmers, such as pest eductions or yield improvements
Genetic analysis for resistance to Sitophilus zeamais (Motschulsky) among provitamin-A maize germplasm
Get PDFMaize biofortification is adopted as strategy to circumvent the high risk of vitamin A deficienc, accentuated by high incidence food losses due to storage insect pests in most developing countries where maize is an important staple crop. This study was initiated to understand the mode of inheritance for resistance to storage weevils among provitamin-A germplasm. A total of 72 provitamin-A maize testcross hybrids were evaluated for agronomic and adaptive traits in three sites, Namulonge, Serere and Ngetta in Uganda during the main season of 2015. Based on genotype x environment analysis of field traits, resultant grain from two divergent environments (Namulonge and Serere) were screened for resistance against Sitophilus zeamais in a no-choice laboratory. Line by tester analysis of combining ability indicated that both additive and non-additive gene effects were important in controlling the resistance parameters, including adult mortality, F1 insects which emerged, Median Development Period, Index of Susceptibility and Grain damage. Two provitamin-A inbred lines, CLHP0014 and CLHP0005 showed high GCA effects for reduced infestation with storage weevil. Broad sense heritability was moderate (0.19 ≤ H2 ≤ 0.59) and Narrow sense heritability (h2) was low ranging from 0.19 to 0.24. The two inbred lines with desirable GCA effect for weevil resistance could be used in the development of resistant breeding population. However, the low heritability of the trait observed, suggested that effective breeding methods be deployed to increase resistance to storage weevil, concurrently with research efforts to develop high nutritional quality maize varieties
Comparison of biomass production, growth and solar energy utilization in specialty vs normal maize genotypes at different developmental stagesComparison of biomass production, growth and solar energy utilization in specialty vs normal maize genotypes at different developmental stagesComparison of biomass production, growth and solar energy utilization in specialty vs normal maize genotypes at different developmental stagesComparison of biomass production, growth and solar energy utilization in specialty vs normal maize genotypes at different developmental stagesComparison of biomass production, growth and solar energy utilization in specialty vs normal maize genotypes at different developmental stages
Get PDFA great deal of research has been carried out to evaluate dry matter accumulation and solar radiation utiliza- tion in normal maize genotypes whereas limited information is available on special genotypes such as high oil and high protein maize. In this paper, we made a comparative analysis on biomass production, solar radiation utiliza- tion and growth at five different stages before and after flowering in normal (B73 and Mo17) and specialty maize (IHO and IHP) lines. Specialty maize genotypes were from 70th cycle of Illinois Long Term Selection. We used 12 directly-measured traits, 10 energy calculations and 6 time interval computations obtained from measurements in five developmental stages. A nested design was used to compare temporal changes in the observed traits.
We found significant differences between specialty and normal maize genotypes for most variables throughout the developmental stages. Normal genotypes had higher plant height than special ones. IHP strain had higher ex- panded leaf area than others, especially around the flowering. IHO produced higher dry matter per leaf area faster in the early stages and stayed green for longer, resulting in high values for total dry matter production and calcu- lated energy equivalent. Radiation use efficiency (RUE) was higher in specialty maize compared to normal maize genotypes. The highest RUE was observed in IHP (1.36 g Mj plant-1) around flowering stage. Overall, specialty and normal genotypes showed significant differences for some agromorphological and physiological traits as well as energy utilization and conversion into dry biomass
Determination of susceptible growth stage and efficacy of fungicidal management of Curvularia leaf spot of maize caused by Curvularia lunata (Wakker) Boedijn
Get PDFMaize is an important food security crop along with rice and wheat globally. Losses caused by biotic stresses in maize are substantial and Curvularia leaf spot is important among them. Further management of Curvularia leaf spot is done primarily through chemicals, therefore an attempt was made to evaluate the efficacy of com- monly used systemic and non-systemic fungicides against the pathogen, and most susceptible growth stage for disease development was identified. In vitro evaluation of four systemic and four non-systemic fungicides was done at different concentrations, for checking the growth of pathogen. The data revealed that Carboxin (at 25 ppm) completely inhibited growth of pathogen. Further among non-systemic fungicides treatment of Mancozeb showed maximum growth inhibition (98. 24% at 200 ppm). Under glass house conditions mancozeb was found to be more effective than Carboxin for controlling the disease severity. Further to determine the time of application of fungicides, developmental stage most susceptible to Curvularia lunata was studied. Three growth stages (Knee height stage, Silking stage and Tasseling stage) were compared. Maximum disease index and severity was found at Silking stage (47% and 53.75%, respectively) followed by Tasseling stage (42.5% and 18.4%, respectively) and Knee height stage (37% and 30%, respectively), indicating that the disease progresses with the maturity of the plant and is maximum at the Silking stage. Results suggest that susceptible maize varieties may give higher yield with the optimisation of the time of application of the fungicides and higher economic and environmental gains can be achieved with judicious use of fungicides
Examination of photosynthetic nitrogen use efficiency of field- grown sweet corn (Zea mays L var merit) under water and nitrogen stress
Get PDFThe physiological response to drought stress in sweet corn (Zea mays L var merit) is not well understood. Water and nitrogen utilization properties of leaves can play key roles in plant drought tolerance. During the grain-filling period, increasing photosynthesis per unit plant N, namely photosynthetic N-use efficiency (PNUE) is a potential way to increase N-utilization efficiency (NUtE). The objective of this study was to determine whether the PNUE within the canopy is optimized as a method of maximizing canopy productivity under low N conditions and/or wa- ter stress. Sweet corn plants were grown in the field in two consecutive years with three N levels (0, 175, and 225 kg N ha−1) and two water regimes (100 and 60 percent field capacity). Throughout the grain-filling period significant interactions of irrigation regime x nitrogen fertilization on specific leaf N (SLN), net photosynthetic rate (P ), PNUE (calculated as P /SLN), stomatal conductance (gs), transpiration rate (E) and green leaf area (GLA) were measured every 10 d after silking (DAS). Significant differences in SLN, P , gs, E, and PNUE occurred in leaves. Ear FM with- out N (N0) (13.69 and 15.56 Mg ha−1 across 2 yr) was 37% and 45% and 34% and 41% less than the average of N125 and N225 across both years, but physiological NUtE increased by 21% without N. Correspondingly, PNUE at high levels of N was similar to that of the full irrigation, with both of them having smaller PNUE than the lower of N. In conclusion, improved whole-plant NUtE under water stress and with N0 may both contribute to the high degree of physiological acclimation of sweet corn to drought and the overall increase in PNUE in the leaves
Assessment of salinity tolerance and SSR profile differentiation in nine maize genotypes (Zea mays L)
Get PDFThe low productivity of maize in Iraq is resulting from many factors that relate to insufficient knowledge of the genetic sources of germplasm used for crop improvement. A major goal of this project was to find the phenotypic, and genotypic variations by using salinity stress and Simple sequence repeat markers among nine maize geno- types. Genetic variation for salt tolerance was assessed in nine maize genotypes using four salinity levels (control,
50, 100, and 150 mM NaCl). Seedling of each genotype was compared to their growth under control and saline conditions. Salt stress (sodium chloride) markedly reduced the germination percentage, shoot and root lengths and fresh and dry masses. However, Dhqan, Fajr 265, Talar were considered as tolerant genotypes while Medium
791 defined as sensitive genotype.
Genotypic analysis was carried out using 18 SSR primers. A total of 46 polymorphic alleles were perceived among the maize genotypes with a range of 1–7 polymorphic bands were detected with size ranging from (90 to
500 bp) along the different maize genotypes. Polymorphism information content, marker index and gene diversity ranged from 0.178 to 0.788, 8.900 to 68.800, and 0.198 to 0.815, respectively. Dendrograms were constructed based on total microsatellite polymorphism, and nine genotypes were grouped into three major clusters. The analysis of molecular variance results revealed 17 and 83% of the total variation between and within populations (local and Iranian). The results confirmed the efficiency of SSR (Simple Sequence Repeat) markers in the detection of genetic variation among maize genotypes
Heterosis and growth in a developing maize plant
Get PDFHeterosis has been extensively studied for nearly a century, yet genetic and biological mechanisms underlying the phenomenon remain elusive. This study extends our understanding of heterosis in maize (Zea mays L) by examining heterosis in the language of growth and development–growth rate, duration of the linear phase, and final trait value. By utilizing a set of phenologically uniform genetic materials the confounding effect of differences in development were eliminated. Using two parental inbred lines and the F1 hybrid, heterosis was examined using logistic growth curves for a series of vegetative and reproductive traits across stages of development (V-stages). Vegetative and reproductive traits examined in this study displayed the classic sigmoidal growth curve. More im- portantly these curves were occurring at the same developmental time points in the F1 and parental inbred lines. In short, heterosis confers an advantage to the F1 that occurs early in development in terms of growth rate and while the growth rate of the F1 and parental lines eventually coalesce, that initial advantage due to heterosis is maintained throughout the lifecycle of the plant resulting in a larger final trait valu
Phenotypic evaluation of a diversity panel selected from the world collection of sugarcane (Saccharum spp) and related grasses
Get PDFLong-term improvement of sugarcane and energy cane (complex hybrids of Saccharum spp) cultivars can be enhanced by breeding with the type of diverse germplasm available at the World Collection of Sugarcane and Related Grasses (WCSRG) maintained in Miami, Florida. To evaluate germplasm in the WCSRG for breeding pur- poses, a diversity panel was selected with approximately 300 accessions and planted at Canal Point, FL in three replications. These accessions were measured for stalk height and stalk number multiple times throughout the plant-crop growing season and for Brix and fresh biomass during the 2013 harvest. First-ratoon stalk height, stalk number, stalk diameter, internode length, Brix, and fresh and dry biomass were evaluated in 2014. The highest correlations were found between early season measurements and harvest traits. Hybrids had higher fresh weight and Brix while Saccharum spontaneum had higher stalk number and dry mass. According to the principal component analysis, the diversity panel was divided into two groups. One group had accessions with high stalk number and high dry biomass like S. spontaneum and the other had accessions with higher Brix and fresh biomass such as S. officinarum. In first ratoon, there were 110 accessions not significantly different in Brix from the sugarcane commercial standards, including 10 S. spontaneum accessions, and 17 and six accessions that were higher than commercial standards in dry and fresh mass, respectively. This study shows the variability in traits of interest and the breeding potential of accessions within the WCSRG for sugar-and energy-cane cultivar development