CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Effects of a clove oil extract on eggs and second-stage juveniles of Meloidogyne incognita (Kofoid et White, 1919) Chitwood, 1949
Get PDFTrials were carried out in vitro to evaluate the action against Meloidogyne incognita (Kofoid et White) Chitwood of the clove oil extract ABT-EU04® (Xeda International S. A.), whose active principle is derived from buds of Syzygium aromaticum (L.) Merrill et Perry. Three aqueous concentrations of the product (0.125%, 0.25% and 0.50%) were tested on M. incognita unsegmented and embryonated eggs and on second-stage juveniles, both free and included in the egg masses. The experiment, run twice, was carried out in small glass containers in the dark at a constant temperature of 25°C. The data from the two tests were statistically analysed. The clove oil extract stopped the embryogenesis of eggs and showed a complete nematicidal action against second-stage juveniles both free and of the egg masses. These properties make this product an interesting tool for a novel control strategy in nematode pest management
Classification of argentine maize landraces in heterotic groups
Get PDFThe genetic diversity of maize (Zea mays L) is a valuable and strategic natural resource that plays a key role in the breeding progress. However, exploitation of genetic variability from landraces has not reached a significant level of utilization in breeding programs in Argentina yet. In order to establish their breeding potential, the best 15 out of a group of about 300 landraces from Argentina, were evaluated for various agronomic characters in testcrosses with five lines representing different heterotic groups. Testcrosses were evaluated in nine environments during two growing seasons. A factorial array of those landraces and tester lines was used. Differences for landraces, testers, and landrace x tester interactions were detected for ear diameter and length, ear attachment and plant height, and grain yield. Yield data were further analyzed following additive main effects (landrace and tester) and multiplicative interaction (landrace x tester) models. The first two principal components were significant and accounted for 67% of that interaction. The first axis was consistent with the Argentine flint vs. US dent (Mo17), and US dent (B73) vs. US dent (Mo17) heterotic patterns. The second axis exhibited a contrast between Argentine flint and US dent (B73 or B73 derived line) heterotic groups. The first two principal components of the landrace x tester interaction and mean performance of testcrosses were considered to identify eight landraces as parents of three composite populations
Evaluation of maize (Zea mays L) inbred lines for yield component traits and kernel morphology
Get PDFThe economical production of the seed of any hybrid maize (Zea mays L) variety is dependent on the parental characteristics of the inbred line used as the seed parent. Grain yield, thousand-kernel weight, ear length and kernel morphology are traits that are important in determining the suitability of an inbred line for use as a seed parent in a seed production field. In 2009, replicated field trials at Janesville, WI and Stanton, MN included 27 maize inbred lines obtained from the North Central Regional Plant Introduction Station in Ames, IA. Inbred line evaluations included measurements of grain yield, thousand-kernel weight, and ear length. Separation of the harvested seed into the different size classifications based on kernel morphology allowed further characterization of inbred lines. Significant differences existed among inbred lines for grain yield, thousand-kernel weight, ear length and kernel morphology. Among this group of inbred lines, ear length appeared to make a greater contribution to grain yield than thousand-kernel weight. Correlation analysis indicated that a strong negative relationship exists between kernel morphology types classified as “large rounds” and “medium flats”, with the latter group being the more desirable of the two. The results of this study suggest that plant breeders may want to consider evaluating inbred parents for their kernel morphology before beginning a breeding project or before selecting an inbred to serve as the seed parent in a production field
Anomalous fertilization in haploidy inducer lines in maize (Zea mays L)
Get PDFA detailed investigation was carried out to study the exact cause and the sequence of events leading to the origin of high frequency of haploids in the high haploidy inducer lines (Stock 6 lines) in maize (Zea mays L). Microtome sections and isolated embryo sacs were observed to understand the fertilization process in maize. These studies helped in understanding the normal fertilization process and also in tracing out a few anomalous fertilization events in these ovules. The study indicated that, haploid embryos in these lines arise due to a failure in the fusion of the sperm nucleus and the egg cell, after the release of sperm nuclei from synergid into the embryo sac, with the egg cell being induced to develop parthenogenetically into a haploid embryo
The conventional and contemporary technologies in maize (Zea mays L) breeding at Maize Research Institut Zemun Polje
Get PDFBroad genetic variability of starting biological material is crucial prerequisite for the successful breeding program. Maize Research Institute, owning Gene bank with more than 6,000 accessions consisted of the local and introduced collection, has the opportunity for the investigation both fundamental genetic processes, pre-breeding and breeding for commercial purposes. To search for new sources of maize drought tolerance Gene bank accessions were scored visually on stay-green phenotype and total appearance. More than 50 genotypes have been identified as a potential source for drought tolerance. Besides breeding on improved storage protein quality decreasing of phytate content in kernel is also under the consideration, because the most phosphorous is bound in phytate. In breeding program it is desirable to have genotypes with higher content of available phosphorous (P) not bound in phytate. Among 60 analyzed populations from Gene bank only one has been determined to have very low phytate content and will be used in maize breeding program on low phytate in kernel. Process of maize breeding, to get high yielding hybrids, begins by the genetic variability determination of starting breeding material, either populations or selected inbred lines. Genetic divergence of parental inbred lines is main step to get high heterotic effect in yield after crossing. Use of different molecular markers allowed cluster analysis by use of UPGMA methods and select high number of genotypes to be included in crossing process
Is Rhus-living Eriosomatinae aphid in Turkey really a new species?
Get PDFSeven alate females collected on Rhus sp. by Dr. Murat Aslan in Turkey are re-studied. Originally considered as an undescribed species, the specimens are determined as Baizongia pistaciae (L.). Misidentification of the host plant probably contributed to lead on the initial confusion. Morphological measurements and ratios of diagnostic characters for the alatae are provided
Assesment of genetic diversity and relationships among maize inbred lines developed in Italy
Get PDFThe genetic diversity pattern of a sample of 144 maize inbred lines comprising 106 Italian entries, considered representative of the breeding material developed at the Bergamo Maize Breeding Station, and a sample of 38, mainly US Corn Belt based, reference lines was accessed using AFLP markers. A total of 811 polymorphic fragments were identified. Exploration of the variation disclosed by the lines by means of principal component analysis (PCA) and hierarchical clustering allowed their division into major heterotic groups. The obtained grouping of the inbred lines reflected pedigree information and resulted in the identification of major clusters derived from Lancaster Sure Crop (LSC), Iowa Stiff Stock Synthetic (BSSS), and miscellaneous heterotic breeding material. AMOVA statistics, performed on the established genetic structure, revealed a high proportion of variance between individuals and among populations stressing the high polymorphic nature of the maize pool analyzed. Regarding population structures, the genetic distance among populations (FST = 0.50 } 0.1) and the degree of inbreeding within groups (FSC = 0.46 } 0.1) did not diverge significantly, while both significantly differed from the degree of relatedness between markers within groups (FCT = 0.06 } 0.04). In conclusion, the results presented indicate that AFLPs are useful in assigning inbred lines to heterotic groups and for superior line development with the aim to maximize heterosis and consequently yield performance
Temperature at night affects the genetic control of acclimation to cold in maize seedlings
Get PDFAlthough suboptimal temperatures during maize (Zea mays L) seedling growth are known to result in decreased photosynthetic efficiency due to a combination of temperature and light stress, details remain scant on the impact of low night temperatures on photosynthetic activity. To better understand the role of night temperature on the acclimation of the photosynthetic apparatus to suboptimal temperature, a QTL experiment was conducted with the IBM302 population. Seedlings were grown under optimal temperature (24/22°C, day/night) or under subopti¬mal temperatures (17°C day and 6 or 13°C night). The two parental lines, B73 and Mo17, responded somewhat differently to suboptimal temperatures, as revealed by measurements of the operating quantum efficiency of PS II (Fq’/Fm’), the maximum quantum efficiency of PS II primary photochemistry (Fv/Fm) and leaf greenness (SPAD). While Mo17 showed very little change in response to the temperature at night, B73 exhibited a lower photosyn¬thetic performance at 13°C than at 6°C at night. At 17/6°C the photosynthetic efficiency of both genotypes was similar. These observations were supported by QTL analyses. A major QTL for photosynthesis-related traits was detected on chromosome 5 with the favorable allele contributed by Mo17. This QTL showed a lower additive effect at a temperature of 6°C than at 13°C during the night and appeared to be the major factor explaining the differential response of the parental lines to changes in the temperature at night. As potential candidate genes for this locus, ivr2 (coding for an acid vacuolar invertase) and a2 (coding for an anthocyanidin synthase) were identi¬fied. QTL analyses for invertase activity and anthocyanin content revealed a QTL for invertase activity near the ivr1 gene and a QTL for anthocyanin content close to the r1 locus, both, however, were not related to the major QTL for photosynthesis-related traits. Comparative QTL analyses of photosynthetic traits of this population and other pulished studies revealed conserved QTL regions on chromosomes 6 and 8
Grain quality-related traits in maize: gene identification and exploitation
Get PDFMaize grain is a relevant source of food, feed, and industrial row materials. Developing plants with improved grain structure and quality traits involves the ability to use existing genetic variation and to identify and manipulate economically important genes. This will open new avenues for designing novel variation in kernel size, structures, and composition and will provide the basis for the development of the next generation of specialty maize. This paper provides an overview of current knowledge on the identification and exploitation of genes affecting the development, structure, and composition of the maize kernel with particular emphasis on pathways relevant to endosperm growth and development, and biosynthesis of storage proteins, starch, lipids, and carotenoids. The potential that the new technologies of cell and molecular biology will provide for the creation of new variation or novel compounds in the future are indicated and discussed
Silage maize (Zea mays L) ripening behaviour affects nitrate leaching over following winter
Get PDFFor economical and environmental reasons nitrogen management is of major importance in growing silage maize (Zea mays L). However, studies to improve N management are often restricted to fertilization measures. Therefore we investigated management effects besides fertilization on nitrogen utilization in two field experiments over two years on an eutrophic sandy soil. Experiment 1 examined the effect of row distance (0.35 m and 0.70 m) and har¬vesting time (premature, mid September; common practice, beginning of October, late harvest, end of October) in a two-way factorial design. In experiment 2 five maize varieties, differing in habitus and characteristic of ripen-ing, were grown using a one-way factorial design. Nitrate leaching over winter was determined by the suction cup method. The row distance showed no significant effect neither on the soil mineral nitrogen content (SMN) in autumn nor on the amount of nitrate leaching. However, SMN and nitrate leaching were affected by the harvest time with significantly lower values for the early harvest. In the second experiment significant differences among genotypes were found with nitrate leaching rates between 52 and 77 kg NO3-N ha-1. We conclude that the effects of harvesting time and variety on nitrate leaching were related to the stage of maturity of silage maize at harvest. Nitrate leaching during winter was lower when maize plants where prevented from sustained metabolic activity in autumn, either by premature harvest as shown in experiment 1 or by enhanced physiological ripening as in experi¬ment 2