CREA Journals (Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria)
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Growth, yields and nitrogen use of open pollinated and hybrid maize (Zea mays L) as affected by organic matter and its placement in minor seasons of Asia
No full textSustainable maize (Zea mays L) production in smallholder cropping systems of South Asia require combinations of organic matter and mineral fertilizers, especially nitrogen, when the crop is subjected to water stress in the minor seasons. As the cultivation of hybrid maze is being promoted in these nations, field studies over two minor seasons evaluated the impact of three types of common organic materials and their method on incorporation on root growth, seeds yields and nitrogen use patterns of an open pollinated (OPV) and a hybrid variety of maize. The growth and yields of the OPV were higher than those of the hybrid, illustrating the greater adaptability of this variety to the drier conditions of minor seasons. The least beneficial impact of organic matter on growth, yield and nitrogen use was with rice straw, a low quality organic matter, while Tithonia leaves promoted root growth. Application of Gliricidia leaves produced the highest yields followed by the use of Tithonia. N use patterns were enhanced to similar extents by the addition of Tithonia and Gliricidia leaves, and the beneficial impact was greater than when rice straw was used. Incorporation enhanced the benefits of the organic matter, especially in the hybrid, which produced lower yields, which is considered less adaptable to the environments of this season. The benefits of using good quality organic matter and its incorporation on maize growth, productivity and the utilization patterns of nitrogen in the minor dry seasons of South Asia was evident in this field study
Response of nitrogen nutritional indices of maize leaves to different mineral-organic fertilization
No full textMaize crop growth rate during the course of vegetation is strongly dependent on nitrogen supply. The most critical stages of maize response to this nutrient are exhibited both in very early growth stages, as related to the stage from five (six) to eight leaves, and in the period from tasselling to the blister stage. Among many indicators of plant nitrogen nutritional status, the most promising include nitrate reductase and acid invertase activity, since the enzymes significantly affect the growth of new tissues. Two series of field experiments were conducted in 2009 and 2010 to evaluate the effect of six fertilization treatments, differing in the prevailing source of nitrogen (from pure mineral to classical organic), on nitrate concentration, nitrate reductase and acid invertase activity and finally on the assimilation area of a single maize plant or the ear leaf. A significant effect of each fertilization treatment on all the examined maize plant characteristics was observed, but it was mostly seasonally variable. Nitrate reductase was linearly affected by the nitrate concentration in maize leaves. Both evaluated indices of acid invertase showed a curvilinear effect on the maize plant morphological characteristics. Therefore it can be concluded that excessive acid invertase activity may inhibit the growth rate of the maize assimilation area in the flowering stage
Yield of tropical Asian maize (Zea mays L) at alternating row irrigation and at severe drought
No full textDrought is a major reason for inconsistent grain yield of maize in lowland tropical and subtropical areas. In bimodal rainy seasons with unequal amounts of rainfall, the shorter season requires germplasm with sufficient residual yields at various situations of low water availability. Thus farmers will avoid the risk of cultivation failure. The respective adaptation of eight Thai hybrids was tested in two dry seasons from late November 2003 to April 2005. Furrow irrigation of 40 mm was applied at seven days intervals from planting to physiological maturity (control, W1); 50% less water supply than W1 from the sixth week onwards by alternating irrigation of one of two rows (W2); withholding water from 5 weeks after planting to the beginning of anthesis (W3). At W3, three hybrids excelled with yields above 350 g m-2, i.e. residual yields of more than two of them performed very well at W2 too, with more than 650 g m-2, a residual yield of about 80%. This genetic range is encouraging to breed for earlier hybrids that can be cultivated in the minor rainy season with a reduced risk of failure
Severe damage caused by Meloidogyne artiellia on cereals and leguminous in Sicily
Get PDFThe root-knot nematode Meloidogyne artiellia Franklin has been reported in various Italian regions on host plants belonging to the families Graminaceae, Leguminosae and Cruciferae, on which it is responsible for severe yield losses. It had never been detected in Sicily. In spring 2008, the nematode was found in different legume and cereal fields in the area of Caltagirone (province of Catania, Sicily). Fields infested with the nematode showed patches of stunted, chlorotic, withered and dwarfed plants. Moreover, ears of wheat were small and kernels appeared dried; finally, roots were scrubby. Infected plants were durum wheat (Triticum durum Desf.), barley (Hordeum vulgare L.), chickpea (Cicer arietinum L.), broad bean (Vicia faba L.), lentil (Lens culinaris Medik.) and vetch (Vicia sativa L.) Root observations showed brownings, small galls and mature females bearing egg masses and larvae at root bifurcations
Temporal dynamics of kernel set of tropical sweet maize (Zea mays L.) as influenced by genotype and mild drought
Get PDFMaize grain yield is often affected by drought stress at flowering. Fast and synchronous emergence of silks probably is the key to high kernel set but non-destructive methods to follow the temporal grain set were missing. We solved this problem by marking flint kernels on the ears of sweet maize to reflect daily kernel set, as modern sweet maize is quite similar in vigor to field maize in Thailand. The effects of mild pre-anthesis drought stress and of the genotype were examined in two experiments (over two years both). The highest number of kernels resulted from pollination on the first or second day of silking. More than 90% of the kernels per ear were usually set by day four or five. Mild drought stress reduced the number of kernel-bearing positions along the ear as well as the number of kernels per position on each day of pollination in 2007 but there was no significant deviation in the principal grain set curve. As a consequence of mild drought stress, the differences in daily kernel set between the two water regimes were rather small compared to the differences among genotypes, for which genotype-specific deviations from the general pattern of daily kernel set were observed. Most important, a new tool exists now to reliably study variable stress situations, using normal grains on sweet maize ears or yellow grains on white grain ears as visual marker systems
Transcriptional profiling of Zea mays genotypes with different drought tolerances – new perspectives for gene expression markers selection
Get PDFDrought is considered to be one of the greatest limiting factors in agriculture. Therefore, the ability of plants to adapt to drought conditions is crucial to sustain worldwide crop production. The aim of this work was to identify gene expression markers for drought tolerance in Zea mays with the potential to assist breeding. Selected maize genotypes were characterized with respect to drought tolerance by measurements of the relative water content after drought stress conditions. Tolerant genotypes were screened for up-regulated genes in drought conditions detected by previous microarray hybridizations. Five cDNAs coding for drought inducible genes in maize were identified and further characterized by semi-quantitative reverse transcription polymerase chain reactions. The expression levels of two of them (MZ00023411 and MZ00037881) allow a significant discrimination between toler¬ant and susceptible genotypes. In tolerant genotypes (MK01, MK01xRF7, 002x250) the expression level of these genes was at least twice higher as compared to susceptible genotypes (XL12, 005, 005x301) throughout all condi¬tions tested. Almost for all tolerant genotypes were registered significant differences (P≤0.05), versus susceptible ones, in expression of these genes. Specific primers for these two genes allow discrimination of drought tolerant and susceptible maize genotypes even after 2h of dehydration stress based on expression level and are suitable as potential gene expression markers, associated with drought tolerance
Utilizing Leafy genes as resources in quality silage maize breeding
Get PDFThe primary goal of silage maize production is to obtain the greatest possible amount of digestible nutrients. Although it is not of the highest value in terms of starch, leaves provide ruminants with sufficient amount of green mass and facilitate nutrient uptake. The nutrient and fibre content of leaves at harvest affect the quality of silage. In cooperation with Glenn Seed Ltd, the Agricultural Research Institute of HAS had an opportunity to use an inbred line carrying the dominant allele Leafy1 (Lfy1). The number and surface area of leaves were measured in various hybrid combinations, and the hybrids and parents were compared morphologically. The combinations causing the highest heterosis were identified. Compared to lines without Lfy1 gene and hybrids in the same maturity group, these lines had an additional 3-4 leaves above the ear on average, resulting in an extra 30-40% leaf area. The hybrid Siloking (Lfy) produced 50% more leaves above the ear than the standard, leading to an extra 40% leaf area. The results demonstrate that the increased total leaf area of Lfy silage hybrids and the number of leaves above the ear, ensure that new leaves with high sugar content capable of photosynthesizing can develop until the end of grain filling. The increased leaf-mass produced by Lfy hybrids may be utilized, bearing in mind the relevant guidelines by the European Union, also as biogas raw material in sustainable energy management
Maize synthetics from a mixture of single, three-way, and double cross hybrids using inbreeding coefficients and mean predictions
Get PDFEquations for inbreeding coefficient and mean prediction were calculated for a synthetic made with a mixture of single, three-way, and double cross hybrids. As inbreeding and mean predictions for the three types of hybrids was already known, corresponding results for inbreeding and mean prediction for the hybrid mixture were ob¬tained with relative ease
Preliminary results of variability in mechanical-induced volatile root-emissions of different maize cultivars
Get PDFThe current study was conducted to obtain more information on the specificity and variation of the volatile com¬pounds, which are released from the root system of different lines and hybrids of Zea mays plants. European (12 genotypes) and North American (5 genotypes) genetic material was included (15 maize hybrids and 2 maize inbreds). The results of our study have shown that roots of European and American maize genotypes secrete dif¬ferent relative amounts of linalool, a-caryophyllene and b-caryophyllene, which depend on genotype and on the pretreatment of the roots (various mechanical damages)
Testcross performance of doubled haploid maize lines derived from tropical adapted backcross populations
Get PDFDoubled haploid (DH) lines produced by in vivo induction of maternal haploids are routinely used in maize breed¬ing. The present study was carried out to assess the performance of 75 doubled haploid maize testcrosses and six checks tested across four locations in Kenya for grain yield, agronomic traits and reaction to major leaf diseases. The 75 DH lines were derived from the backcross (BC1) plants of two CIMMYT bi-parental crosses. Significant location, genotype and genotype x location effects were observed for grain yield and anthesis-silking interval (ASI). Genotypes were significantly different for reaction to leaf blight and gray leaf spot. Location explained 69% of the total phenotypic variance while both genotype and genotype by environment interaction effects contributed 4% each. Fifteen DH testcross hybrids yielded better than the best commercial check, WH505 (5.1 t ha-1). The best DH testcross hybrid (CKDHH0223) averaged over the four locations yielded 29.5% higher than WH505. These results indicate that maize testcrosses developed from DH lines produced as high a grain yield and as acceptable agro¬nomic traits as the commercial hybrids developed through conventional pedigree methods. The DH lines identified in the study may be useful for improving yield and disease resistance in maize breeding programs in eastern and southern Africa