CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Molecular characterization of tropical maize inbred lines using microsatellite DNA markers
Get PDFAn insight on diversity and relationships among germplasm is important in any breeding program for crop improve¬ment. The main objectives of our study were to: (i) determine the level of genetic diversity within mid altitude maize inbred lines resistant to weevils, aflatoxin accumulation and drought, (ii) to suggest potential heterotic groups using their genetic structures and distance based on cluster analysis with the aim to generate broad based source germ¬plasm for mid altitude maize breeding program with combined traits of importance against Aflatoxin accumulation. In this study, 25 SSR markers were used to finger print forty two maize inbred lines to assess the genetic diversity, genetic relationships, and their population structure. A total of 184 alleles were identified at all the loci with an aver¬age of 7.36 and a range between two and 19 alleles per locus. The major allele frequency varied from 0.17 to 0.90 with an average of 0.49 while the minor allele frequency varied from 0.10 to 0.83 with an average of 0.51. The gene diversity values varied from 0.18 to 0.92 with an average of 0.65. Average heterozygosity percentage of the inbred lines was 4%, ranging from 0% to 2%, indicating the low level of heterozygosity within the inbred lines. The aver¬age polymorphism information content (PIC) was 0.61. A dendrogram constructed using unweighted Neighbour Joining algorithm suggested three heterotic groups among the inbred lines. The three heterotic patterns based on the SSR markers need to be verified by field testing to confirm what appears to be promising alternative heterotic patterns. The fixed pattern detected using SSR markers could potentially contribute towards effective utilization of the inbred lines for the exploitation of heterosis and formation of genetically diverse sources population
Effect of water availability and genetic diversity on flowering phenology, synchrony, and reproductive investment in maize
Get PDFCrop yield of monoecious species like maize (Zea mays) relies on simultaneous flowering of male and female inflorescences to ensure pollination. Yet productivity may be reduced if environmental conditions reduce floral synchrony or if plants within a field do not overlap sufficiently in flowering periods. We experimentally manipulated water availability and measured its effect on flowering, including the anthesis-silking interval (ASI) and crop yield components in open-pollinated (OP) and hybrid corn cultivars. Although watering treatments did not affect traits, we did detected cultivar-specific phenological and yield responses. Hybrid plants were earlier to silk than OP plants, which tasseled for longer, had a longer ASI, and lower yield components. The less diverse hybrids also expressed less variation in ASI. We suspect other methods for reducing moisture in the field, including earlier moisture removal, might have better elicited a biological response in maize. Nevertheless, because shorter ASI is genetically correlated with increased drought tolerance, we predict this hybrid may be more resilient than the OP under more extreme drought scenarios. Consideration for how genetic diversity found in OP varieties and crop landraces may respond to variation in moisture availability apparent with climate change may be warranted
Identification of quantitative trait loci for resistance to Curvularia leaf spot of maize
Get PDFResistance of maize to Curvularia leaf spot (CLS), a severe foliar disease in hot and humid maize growing areas, is quantitative in nature. The F2:3 families derived from the cross between the resistant Shen137 and susceptible Huangzao4 inbred lines, were used to detect QTL conferring resistance to CLS. Four QTL were detected on chromosomes 1, 3, 8, and 10, and could totally explain 38.8% of the total phenotypic variation. Another F2 population consisting of 63 highly resistant and 59 highly susceptible plants, selected from 822 F2 plants, was also subjected to QTL analysis for CLS resistance. Four QTL were found on four chromosomes 1, 4, 9, and 10, which accounted for 45.7% of the total phenotypic variation. Interestingly, a major resistance QTL, qCLS10.4, on chromosomal bin10.04 was consistently detected in both populations. Apart from additive effect, dominant effect also exerted significant influence on resistance to CLS. Therefore, breeders should avoid an early generation selection of resistant individuals in breeding program
A survey on pest insects of fiber and grain sorghum in northern Italy
Get PDFIn the Po valley plain grain sorghum (Sorghum bicolor) has been introduced in the last decades for cattle feed production. More recently fiber sorghum has been tested to be used for electric power production. Since little is known about the sorghum insect pest community in northern Italy, a research was carried out in a study area located in the central western area of the Po valley. Grain sorghum plots and fields were studied between 2008 and 2011. No insect pest of economic importance was recorded in grain sorghum cultivations. Population density of the aphid Rhopalosiphim maidis was very low, as well as the one of the European Corn Borer (ECB, Ostrinia nubilalis, Lepidoptera Crambidae). Lygus rugulipennis (Hemiptera Miridae) tended to colonize grain sorghum after panicle development, but densities were not a matter of concern. In fiber sorghum plots ECB populations did not result noxious, while R. maidis density was higher than the one on grain sorghum, but infestations did not signifi¬cantly affect the development of the stalks, being localized only on panicles during their first stage of develop¬ment. The production of cyanogenetic compounds by young sorghum plants is likely to be an effective protection against ECB first generation larvae, while earlier harvest time of both grain and fiber sorghum compared with maize later harvest time prevents significant damages caused by ECB second generation larvae. Sorghum requires less water than maize. Such a condition, joint to the weak susceptibility to insect pests, could favour a further increase of sorghum cultivations in northern Italy
Maize (Zea mays L) cultivars nutrients concentration in leaves and stalks
Get PDFThere is pressure for crop residue removal for use as biofuel, animal feed, animal bedding and many other func¬tions which may increase nutrient export. However, there is little information about nutritional composition of maize stover considering the wide variability of cultivars used. The aim of this study was to evaluate the influence of maize cultivar on macronutrient (P, K, Ca, and Mg), micronutrient (Fe, Mn, Zn, and Cu) and Na concentration in leaves and stalks. We selected five pairs of cultivars, ranging from creole to high potential hybrid (creole, commer¬cial variety, single, double and triple cross hybrid). The cultivars were cropped under field conditions in high fertile Rhodic Ferralsol Eutric during two growing seasons. The first was characterized by severe drought (2005/2006) while the second with an abundant water supply (2006/2007). The leaf and stalk concentrations of P, K, Ca, Mg, Fe, Mn, Na, Zn, Cu, and C/P ratio were quantified at maturation stage. The results indicated that the P concen¬tration in leaves and stalks was inversely related to the technological level when simple hybrid was compared to creole cultivars. Similar behavior was observed for K in the leaf and stalk tissues. For Ca, Mg, Fe, Mn, Zn, Cu, and Na, it was not possible to establish the influence of maize selection. The C/P ratio of leaves and stalks underwent influence of the technological level with high values for simple hybrids. Maize selection seems to decrease P and K concentration for two major residue fractions, leaves and stalks
Autocontamination trap with entomopathogenic fungi: a possible strategy in the control of Rhynchophorus ferrugineus (Olivier) (Coleoptera Curculionidae)
Get PDFAn experimental autocontamination trap was devised to infect Rhynchophorus ferrugineus (Olivier), the Red Palm Weevil, adults with entomopathogenic fungi. The aim was to develop an autocontamination device to support integrated R. ferrugineus control programs. In laboratory bioassays, the delivery system successfully attracted, infected and released weevil adults after they contacted cereal substrata inoculated with indigenous strains of Beauveria bassiana (Balsamo- Crivelli) Vuillemin and Metarhizium anisopliae (Metchnikoff) Sorokin. Tests carried out with the experimental traps showed that M. anisopliae was the more virulent pathogen, causing 75% cumulative mortality in adults, while B. bassiana gave a 45% cumulative mortality. Infectivity of M. anisopliae was not affected by different cereal substrata, i.e. wheat and rice, since curculionid cumulative mortality (95%) and treatment efficiency (95% Abbott) were very high on both of them and Red Palm Weevil LT50 was reached within the same time (15 days). Conidial persistence and germinability of M. anisopliae grown on the rice substratum were examined in field conditions inside traps located in sunny and shady positions in spring, summer and autumn. The results showed that the traps preserved fungal inoculum stability longer in spring and summer than in autumn. No significant difference in M. anisopliae conidial persistence was found between sunny and shady traps during the various seasons
Effect of elevated ozone and carbon dioxide interaction on growth and yield of maize
Get PDFThe effect of elevated tropospheric ozone and carbon dioxide interaction were evaluated on the growth and pro¬ductivity of high quality protein maize (HQPM-1) at the research farm of the Indian Agricultural Research Institute, New Delhi. Maize plants were exposed from emergence to maturity for two years to different ozone levels in non fil¬ter air (NF), charcoal filter air (CF), non-filter air with elevated CO2 (NF+CO2), elevated ozone (EO and EO1), elevated ozone with elevated CO2 (EO+CO2) and ambient control (AC) in open top chambers. Elevated ozone significantly decreased growth attributes of leaf and shoot biomass and leaf area index and the yield attributes. Highest values of all the growth and yield attributes were observed in CF treatment. The photosynthetic rate decreased by 24 to 37% and from 41 to 56% under EO (ambient + 25-35 ppb O3) over NF at tasseling and silking stage respectively. The yield increased by 21 to 31% in the sub ambient ozone levels in the CF treatment over non-filtered control whereas it decreased by 13 and 20 % under EO in both the years respectively. The presence of higher levels of ozone EO1 (ambient + 45-50 ppb O3) however made the plant weak and more susceptible to pest attack, result¬ing in a complete loss in yield. The presence of elevated carbon dioxide along with elevated ozone in the EO+CO2 treatment increased the yield by 9 to 10% over EO alone. Elevated CO2 was able to counter the negative effect of O3 on growth and yield parameters of maize to a certain extent
Growth performance of selected eucalypt hybrid clones for SRWC in central and southern Italy
Get PDFEucalypt short-rotation woody crop (SRWC) is becoming an attractive option for energy biomass in Mediterranean dry environments. The present study is aimed at assessing growth performance of selected eucalypt hybrid clones for SRWC in three Italian sites (Massama, Sardinia; Mirto, Calabria; Rome, Latium) compared with Eucalyptus camaldulensis, the most commonly cultivated eucalypt species in Italy. The study identified eucalypt clones with stable and high performance between several alternatives. Results pointed out the declining growth performance observed in the second rotation compared with the first cycle. This is due to the cultivation model, age rotation and harvesting method adopted, which negatively affect the available soil nutrients’ content. The clone/site interaction as for basal area growth at the three investigated sites, suggests a significantly different clones’ performance among sites. Viglio and Velino clones showed the best overall performance and are suggested to be used over the large scale SRWC in central and southern Italy
The box tree moth Cydalima perspectalis (Walker, 1859) continues to spread in southern Europe: new records for Italy (Lepidoptera Pyraloidea Crambidae)
Get PDFThe Box Tree Moth Cydalima perspectalis (Walker, 1859) is an invasive alien species whose original range is in eastern Asia on Buxus species. In Europe, it was first reported in 2006 in Germany, rapidly becoming widespread across the European Union. The danger they present is that larvae develop on commonly planted ornamental bushes Buxus sempervirens L. This work provides an update of Cydalima perspectalis geographic distribution in Italy as well as including new records from Tuscany and the first record from Sicily
Effects of Leptoglossus occidentalis Heidemann (Heteroptera Coreidae) egg age on the indigenous parasitoid Ooencyrtus pityocampae Mercet (Hymenoptera Encyrtidae)
Get PDFLeptoglossus occidentalis is a Nearctic polyphagous coreid capable to feed on cones and seeds of many coniferous plants. In Italy this pest threatens pine nut commercial production and represents a serious concern in protected areas where control by chemicals is restricted. For this reason, new strategies of biological control against L. occidentalis are under investigation. Ooencyrtus pityocampae, an indigenous egg parasitoid of the lepidopter Thaumetopoea pityocampae was recently found to parasitize L. occidentalis eggs. However low parasitization rates in the field were reported. Host egg age is often regarded as a key element in determining host acceptance and parasitoid capacity to exploit host eggs. Therefore, in the current work, the effects of host egg age on parasitization O. pityocampae were evaluated by exposing eggs ranging in age from < 24h to within a day of hatching. O. pityocampae. Results showed that number of parasitized eggs and sex ratio were not significantly influenced by the age of the host eggs. In contrast, female development time resulted to be longer in older eggs. O. pityocampae appeared to be not only flexible to adapt to the new host but also cable to efficiently exploit L. occidentalis eggs containing fully developed nymphs