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Varietal differences and stages of crop harvest have great contributions to biomass quantity and quality of maize stovers, however, little/no studies have been done in these regards. We evaluated three maize varieties: Jibat, Kuleni, and Kolba for their morphological characteristics, dry matter production, and feed quality harvested at milk and dough stages for two years in a randomized complete block design with four replications. Variety had no significant (P>0.05) effect on the measured morphological traits except for cob length (CL). Plant height (PH) and dry matter yield (DMY) were significantly (P<0.001) influenced by year at both harvest stages. The DMY achieved at the milk and dough stages significantly increased by 22.6 and 36.3% in 2020 compared to 2019. At both stages, Kolba and Jibat recorded significantly higher number of cobs per plant, and these varieties also achieved longer leaf lengths at the milk stage than kuleni. We found insignificant (P>0.05) differences among varieties for DMY at milk and dough stages. The fiber contents (NDF, ADF, and ADL) were influenced by varieties only at the milk stage. Thus, Jibat and Kuleni could be appropriate for feed with better quality when harvested at the milk stage. After removing the green cobs for human consumption, the three varieties are also used as animal feed at the dough stage. [ABSTRACT FROM AUTHOR]

Drought is amongst the most important stressors affecting maize production globally. Existing strategies to offset drought impacts are centered around the rapid development of drought-tolerant cultivars through plant breeding. However, under both current conditions and projected climate changes, additional stressors such as insect pests will co-occur. To determine the impact of combined insect and drought stress on drought tolerance in maize, we assessed the effects of Dalbulus maidis, drought, and both stresses combined in drought-tolerant maize hybrids. We measured several maize morphological growth traits (i.e., plant height, stem diameter, shoot weight, root weight, root length, and root-to-shoot ratio) at the end of a 28-day period of pulse-stress and no-stress control exposure. We found that seedling growth declined when both stressors co-occurred. Nevertheless, drought-tolerant maize hybrids remained strongly tolerant to drought regardless of D. maidis infestation. While our results showed that drought tolerance is maintained in drought-tolerant maize seedlings, future studies should address any effects on maize yield. Our study highlights the importance of testing the combined effects of drought and insect stressors to better predict insect–plant interactions in the context of plant breeding for drought-tolerant traits in a changing climate. [ABSTRACT FROM AUTHOR]

Drought is one of the major environmental stresses that negatively affect the maize (Zea mays L.) growth and production throughout the world. Foliar applications of plant growth regulators, micronutrients or osmoprotectants for stimulating drought-tolerance in plants have been intensively reported. A controlled pot experiment was conducted to study the relative efficacy of salicylic acid (SA), zinc (Zn), and glycine betaine (GB) foliar applications on morphology, chlorophyll contents, relative water content (RWC), gas-exchange attributes, activities of antioxidant enzymes, accumulations of reactive oxygen species (ROS) and osmolytes, and yield attributes of maize plants exposed to two soil water conditions (85% field capacity: well-watered, 50% field capacity: drought stress) during critical growth stages. Drought stress significantly reduced the morphological parameters, yield and its components, RWC, chlorophyll contents, and gas-exchange parameters except for intercellular CO2 concentration, compared with well water conditions. However, the foliar applications considerably enhanced all the above parameters under drought. Drought stress significantly (p < 0.05) increased the hydrogen peroxide and superoxide anion contents, and enhanced the lipid peroxidation rate measured in terms of malonaldehyde (MDA) content. However, ROS and MDA contents were substantially decreased by foliar applications under drought stress. Antioxidant enzymes activity, proline content, and the soluble sugar were increased by foliar treatments under both well-watered and drought-stressed conditions. Overall, the application of GB was the most effective among all compounds to enhance the drought tolerance in maize through reduced levels of ROS, increased activities of antioxidant enzymes and higher accumulation of osmolytes contents. [ABSTRACT FROM AUTHOR]

Maize originated as a tropical plant that required short days to transition from vegetative to reproductive development. ZmCCT10 [CO, CONSTANS, CO-LIKE and TIMING OF CAB1 (CCT) transcription factor family] is a regulator of photoperiod response and was identified as a major QTL controlling photoperiod sensitivity in maize. We modulated expression of ZmCCT10 in transgenic maize using two constitutive promoters with different expression levels. Transgenic plants over expressing ZmCCT10 with either promoter were delayed in their transition from vegetative to reproductive development but were not affected in their switch from juvenile-to-adult vegetative growth. Strikingly, transgenic plants containing the stronger expressing construct had a prolonged period of vegetative growth accompanied with dramatic modifications to plant architecture that impacted both vegetative and reproductive traits. These plants did not produce ears, but tassels were heavily branched. In more than half of the transgenic plants, tassels were converted into a branched leafy structure resembling phyllody, often composed of vegetative plantlets. Analysis of expression modules controlling the floral transition and meristem identity linked these networks to photoperiod dependent regulation, whereas phase change modules appeared to be photoperiod independent. Results from this study clarified the influence of the photoperiod pathway on vegetative and reproductive development and allowed for the fine-tuning of the maize flowering time model. [ABSTRACT FROM AUTHOR]

Waterlogging is a severe abiotic stressor causing significant growth impairment and yield losses in many crops. Maize is highly sensitive to the excess of water, and against the background of climate change there is an urgent need for deeper insights into the mechanisms of crop adaptation to waterlogging. In the present study, changes in maize morphology at the 4–5 leaf stage and the expression of three candidate genes for flooding tolerance in plants subjected to six continuous days of waterlogging were recorded in 19 commercial hybrids and in the inbred line B73, with the aim of investigating the current variability in cultivated hybrids and identifying useful morphological and molecular markers for screening tolerant genotypes. Here it was demonstrated that root parameters (length, area, biomass) were more impaired by waterlogging than shoot parameters (shoot height and biomass). Culm height generally increased in stressed plants (by up to +24% vs. controls), while shoot biomass was significantly reduced in only two hybrids. Root biomass was reduced in all the hybrids, by an average of 30%, and significantly in 7 hybrids, while root length and area were even more severely reduced, by 30–55% vs. controls, depending on the hybrid. The earlier appearance of aerial roots seemed to be associated with greater root injuries. In leaves, the transcript of the PFP enzyme (phosphofructokinase), which is involved in glycolytic reactions, was markedly up-regulated (up to double the values) in half the waterlogged hybrids, but down-regulated in the others. The transcript of CYP81D8 (ROS-related proteins) in waterlogged plants exhibited relevant increases or strong decreases in level, depending on the hybrid. The transcript of the AOX1A gene, coding for a mitochondrial respiratory electron transport chain-related protein, was markedly down-regulated in all the treated hybrids. Expression analysis of these genes under extreme waterlogging only partially correlate with the shoot and root growth impairments observed, and AOX1A seems to be the most informative of them. [ABSTRACT FROM AUTHOR]

The evolution of maize (Zea mays L.) is highly controversial given the discrepancies related to the phenotypic and genetic changes suffered by the species, the incidence of human groups and the times in which these changes occurred. Also, morphological and genetic traits of crops are difficult to evaluate in the absence of fossils macro-botanical remains. In contrast in the Tarapacá region (18–21° S), Atacama Desert of Chile, prehispanic settlements (ca. 2500–400 yr BP) displayed extensive maize agriculture. The presence of archaeological macro-botanical remains of maize provided a unique opportunity to study the evolution of this crop, covering a temporal sequence of at least 2000 years. Thus, in this study, we ask how the morphological and genetic diversity of maize has varied since its introduction during prehispanic times in the Tarapacá region. To answer this, we measured and compared morphological traits of size and shape between archaeological cobs and kernels and 95 ears from landraces. To established genetic diversity eight microsatellite markers (SSR) were analyzed in archaeological and modern kernels. Genetic diversity was estimated by allelic frequency rates, the average number of alleles per locus, observed heterozygosity (Ho) and expected heterozygosity (He). Differences between populations and genetic structure were estimated by fixation index FST and STRUCTURE analysis. Our results indicate significant phenotypic differences and genetic distance between archaeological maize and landraces. This result is suggestive of an introduction of new varieties or drastic selective changes in modern times in Tarapacá. Additionally, archaeological maize shows a low genetic diversity and a progressive increase in the size of ears and kernels. These results suggest a human selection during prehispanic times and establish that prehispanic farmers played an important role in maize development. They also provide new clues for understanding the evolutionary history of maize in hyperarid conditions. [ABSTRACT FROM AUTHOR]

Heavy metals are one of the major abiotic stresses that adversely affect the quantity and nutritive value of maize. Microbial management involving the use of plant growth promoting rhizobacteria (PGPR) is a promising inexpensive strategy for metal clean up from polluted soils. Considering these, metal tolerant plant growth promoting nitrogen fixing rhizobacterial strain CAZ3 identified by 16SrRNA gene sequence analysis as Azotobacter chroococcum was recovered from metal polluted chilli rhizosphere. When exposed to varying levels of metals, A. chroococcum survived up to 1400 and 2000 µg mL −1 of Cu and Pb, respectively and expressed numerous plant growth promoting activities even under metal stress. Strain CAZ3 secreted 65.5 and 60.8 µg mL −1 IAA at 400 µg mL −1 each of Cu and Pb, respectively and produced siderophores, ammonia and ACC deaminase under metal pressure. The melanin extracted from A. chroococcum revealed metal chelating ability under EDX. Following application, strain CAZ3 enhanced growth and yield of maize grown both in the presence of Cu and Pb. The dry biomass of roots of inoculated plants grown with 2007 mg Cu kg −1 and 585 mg Pb kg −1 was increased by 28% and 20%, respectively. At 585 mg Pb kg −1 , the bioinoculant also increased the kernel attributes. At 2007 mg Cu kg −1 strain CAZ3 enhanced the number, yield and protein of kernels by 10%, 45% and 6%, respectively. Interestingly, strain CAZ3 significantly reduced the levels of proline, malondialdehyde and antioxidant enzymes in foliage. The roots of inoculated plants accumulated greatest amounts of metals compared to other organs. In kernels, the concentration of Pb was more as compared to Cu. The metal concentrations in roots, shoots and kernels, however, declined following CAZ3 inoculation. Copper and lead had substantial distortive impact on root and leaf morphology while cell death were visible under CLSM and SEM. Conclusively, A. chroococcum CAZ3 could be a most suitable and promising option to increase maize production in metal polluted soils despite the soils being contaminated with heavy metals. [ABSTRACT FROM AUTHOR]

Poultry manure (PM), a rich source for crop nutrients, is produced in ample quantities worldwide. It provides necessary nutrient to soil and has a potential to improve plant water holding availability under semiarid environment. The effect of composted poultry manure (CPM) and irrigation regimes on morpho-physiology of selective maize (Zea mays L.) hybrids (H1 = drought tolerant, H2 = drought sensitive) was investigated in this study. Two field experiments were conducted during 2010 and 2011 under randomized complete block design with split split-plot arrangements and three replications of each treatment. Irrigation regimes (I1 = 300, I2 = 450, I3 = 600 mm) were kept in main plots; the two maize hybrids (H1 and H2) in sub-plots and nutrient levels (L1 = recommended rate of NPK (control), L2 = 8 t ha−1 CPM, L3 = 10 t ha−1 CPM, and L4 = 12 t ha−1 CPM) were arranged in sub sub-plots. The drought tolerant hybrid showed best growth under all treatments. Results revealed that maximum leaf area index (LAI) was recorded with the application of the recommended dose of NPK. Low irrigation regimes (I1 and I2) highly significantly (P < 0.01) reduced the photosynthesis and transpiration rate in both hybrids while application of 12 t ha−1 CPM was able to partially alleviate the effect of water stress on these parameters. Resultantly, the application of 12 t ha−1 CPM enhanced the plant growth and increased grain yield (21%; 4.17 vs 5.27) under limited water availability (I2L4) as compared to the recommended dose of NPK (I2L1). However, the nutrient application under control treatment had maximum grain yield. Therefore, shortage of water for maize production might be partially alleviated by the application of 12 t ha−1 CPM. [ABSTRACT FROM AUTHOR]

The purposes of this study were to develop a dual crop coefficient (Kc) using FAO-56 methodologies and to compare crop evapotranspiration (ETc) measured under field conditions for second-crop silage maize in the Southeastern Anatolia Region of Turkey with the ETc estimated using FAO-56 dual Kc methodologies. For this study, field experiments were conducted in the 2011 and 2012 growing seasons, and the results were evaluated. To compute dual Kc (Kcb and Ke), all climatological data involving the seedling and harvesting dates, growth stages, water holding of soil at field capacity and at wilting point, soil evaporation layer, and crop characteristics were input into a spreadsheet program. The crop stages observed were 15, 25, 40, and 12 days for the initial, crop development, midseason, and late-season stages, respectively, in 2011, and 12, 23, 43, and 13 days, respectively, for the same stages in 2012. The reference evapotranspiration (ETo) was computed daily using the Penman-Monteith equation. All main and intermediate calculations for the dual Kc and its components Kcb and Ke were based on the FAO-56 guidelines. The Kcb values were computed as 0.15, 1.27, and 0.62 for the initial, midseason, and late-season stages, respectively. However, these figures were 0.15, 1.15, and 0.5 in the FAO-56 in the same order. The dual Kc was 0.64, 1.27, and 0.67 in this study for the initial, midseason, and late-season stages, respectively. The maximum ETc rate occurred in midseason, which had an average maximum value of 10.8 mm day-1. The ETc of silage maize for optimal dry matter during the growing season in the years of the study was 519 mm as the average of two growing seasons. The FAO methodology thus insignificantly overestimated the seasonal ETc (536 mm) for silage maize. Thus, the FAO-56 dual Kc methodology can be used to estimate the crop ETc. [ABSTRACT FROM AUTHOR]

In maize (Z ea mays L.), final grain yield is largely determined by kernel number at harvest. The goal of this research was to assess the source of kernel loss and identify the main factors in the process of kernel formation among maize hybrid genotypes comprising semi-compact (JH5) and compact (LD9066) genetic backgrounds (with contrasting tolerance to stand density) under field conditions. Field experiments were conducted in 2014 and 2015. Two hybrids were grown at three sowing dates (early April: SD1, early May: SD2, and late May: SD3) and under three plant densities: D1 (5.25 plants m −2 ), D2 (6.75 plants m −2 ), and D3 (8.25 plants m −2 ). Two sources of kernel loss were assessed and associated with 1) silks failing to emerge from the husk 7 days after silking (loss1) and 2) kernel abortion during the grain-filling period (loss2). The results demonstrated that floret number was significantly influenced by maize hybrid: the semi-compact maize hybrid JH5 had more florets than did the compact maize hybrid LD9066. However, the final kernel number per plant (FKNP) of JH5 was slightly lower than that of LD9066. JH5 had a larger value for both loss1 and loss2 than did LD9066 (22.6% vs 11.9% and 21.0% vs 12.1%, respectively). Moreover, sowing date and plant density also significantly influenced the source of kernel loss. SD1 exhibited a greater value of loss1 than did SD2 and SD3 (24.9%, 15.8% and 11%, respectively) but a lower value of loss2 than did SD2 and SD3 (10.0%, 20.6% and 19.6%, respectively). Plant density had no significant effect on loss1; however, the highest plant density (D3) resulted in the highest loss2 among three plant densities (9.4%, 15.9% and 25.9%). The dynamics of visible silking showed that JH5 requires more time (+1.5 days) to reach 50% maximum visible silks than does LD9066 and has a lower proportion of maximum visible silks at the seventh day after silking. In addition, the apical kernels of JH5 had a relatively longer Dmax (days needed to reach the maximum grain-filling rate) and greater Gmax (maximum grain-filling rate) than did those of LD9066 (+0.5 day and +3.5 mg kernel −1  d −1 , respectively). However, the Wmax (kernel weight at the maximum grain-filling rate) and P (active grain-filling period) of JH5 were much lower than those of LD9066 (-6.4 mg kernel −1 and −8.2 days, respectively). Compared with the semi-compact hybrid, the compact hybrid showed an enhanced ability to resist abiotic stress tolerance, with good fertilization synchronization and a low percentage of kernel abortion. These above-mentioned traits should be considered in breeding programs to further increase the maize yield in China. [ABSTRACT FROM AUTHOR]

Biologically active oligosaccharides, including galactoglucomannan oligosaccharides (GGMOs), affect plant growth and development. The impact of GGMOs is dependent on their concentration, and the plant species and plant parts affected. The aim of this article is to ascertain the effects of GGMOs, GGMOs + Cd 2+ , on growth parameters, morphology, and the structure of maize ( Zea mays L.) roots. We undertook this research because, in monocots, the effect of these oligosaccharides is so far unknown. In our study, GGMOs stimulated primary root elongation, induction and elongation of lateral roots, and biomass production. Their effect was dependent on the concentration used. Simultaneously, GGMOs moderated the negative effect of Cd 2+ on root elongation growth. Besides, GGMOs affected the primary root structure, proven in the earlier development of xylem and Casparian bands, but not of suberin lamellae (compared to the control). The presence of Cd 2+ shifted the apoplasmic barriers closer to the root apex in comparison to samples treated with GGMOs + Cd 2+ . GGMOs do not inhibit Cd uptake into the root directly, but they moderate its effect, and therefore their influence at the structural and metabolic level seems possible. Their positive impact on plant vitality, even in contaminated conditions, strongly indicates their potential application in remediation technologies. [ABSTRACT FROM AUTHOR]

Abstract: Morphological traits for ear leaf are determinant traits influencing plant architecture and drought tolerance in maize. However, the genetic controls of ear leaf architecture traits remain poorly understood under drought stress. Here, we identified 100 quantitative trait loci (QTLs) for leaf angle, leaf orientation value, leaf length, leaf width, leaf size and leaf shape value of ear leaf across four populations under drought‐stressed and unstressed conditions, which explained 0.71%–20.62% of phenotypic variation in single watering condition. Forty‐five of the 100 QTLs were identified under water‐stressed conditions, and 29 stable QTLs (sQTLs) were identified under water‐stressed conditions, which could be useful for the genetic improvement of maize drought tolerance via QTL pyramiding. We further integrated 27 independent QTL studies in a meta‐analysis to identify 21 meta‐QTLs (mQTLs). Then, 24 candidate genes controlling leaf architecture traits coincided with 20 corresponding mQTLs. Thus, new/valuable information on quantitative traits has shed some light on the molecular mechanisms responsible for leaf architecture traits affected by watering conditions. Furthermore, alleles for leaf architecture traits provide useful targets for marker‐assisted selection to generate high‐yielding maize varieties. [ABSTRACT FROM AUTHOR]

A low-cost three-dimensional (3D) plant reconstruction and morphological traits characterization system was developed. Corn plant seedlings were used as research objects for development and validation of the 3D reconstruction and point cloud data analysis algorithms. In this application, precise alignment of multiple 3D views generated by a 3D time-of-flight (ToF) sensor is critical to the 3D reconstruction of a plant. Previous research indicated that there is strong need for high-throughput, high-accuracy, and low-cost 3D plant reconstruction and trait characterization phenotyping systems. This research produced a 3D reconstruction system for indoor plant phenotyping by innovatively integrating a low-cost 2D camera, a low-cost 3D ToF camera, and a chessboard pattern beacon array to track the position and attitude of the 3D ToF sensor and, thus, accomplished precise 3D point cloud registration over multiple views. Specifically, algorithms for beacon target detection, camera pose tracking, and spatial relationship calibration between 2D and 3D cameras were developed for such a low-cost but high-performance 3D reconstruction solution. A plant analysis algorithm in a 3D space was developed to extract the morphological trait parameters of the plants by analyzing their 3D point cloud data. The phenotypical data obtained by this novel and low-cost 3D reconstruction based phenotyping system were validated by the experimental data generated by instrument and manual measurement. The results demonstrated that the developed phenotyping system has achieved promising measurement accuracy, fast processing speed while offering a low hardware cost, lending itself to a practical means of acquiring detailed 3D morphological traits for automated indoor plant phenotyping. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of waterlogging on the growth and photosynthetic characteristics of paired near-isogenic lines of waterlogging-tolerant (Zz-R) and waterlogging-sensitive (Zz-S) waxy corn inbred line seedlings. All plants were grown until the fifth leaves were fully expanded. Subsequently the plants in the pots were submerged in water for 4 d. During the waterlogging period, morphological and photosynthetic parameters related to waterlogging tolerance were examined. After 4 d, a significant decrease was observed in shoot and root fresh mass, net photosynthetic rate, stomatal conductance, transpiration, water-use efficiency, light-saturation point, maximal photosynthetic rate, apparent quantum yield, maximal quantum yield of PSII, and effective quantum yield of PSII photochemistry in waterlogged plants of both genotypes. The Zz-R genotype showed lesser reduction in all mentioned indices when compared to the Zz-S genotype. The inhibition of photosynthesis under waterlogging occurred due to the reduction in stomatal conductance, fluorescence parameters, and chlorophyll content. Thus, our study revealed that the Zz-R genotype can be a source of genetic diversity for important traits such as morphological and photosynthetic parameters. [ABSTRACT FROM AUTHOR]

The maize (Zea mays subsp. mays L.) shoot apical meristem (SAM) is a self-replenishing pool of stem cells that produces all above-ground plant tissues. Improvements in image acquisition and processing techniques have allowed high-throughput, quantitative genetic analyses of SAM morphology. As with other large-scale phenotyping efforts, meaningful descriptions of genetic architecture depend on the collection of relevant measures. In this study, we tested two quantitative image processing methods to describe SAM morphology within the genus Zea, represented by 33 wild relatives of maize and 841 lines from a domesticated maize by wild teosinte progenitor (MxT) backcross population, along with previously reported data from several hundred diverse maize inbred lines. Approximating the MxT SAM as a paraboloid derived eight parabolic estimators of SAM morphology that identified highly overlapping quantitative trait loci (QTL) on eight chromosomes, which implicated previously identified SAM morphology candidate genes along with new QTL for SAM morphological variation. Using a Fourier-transform related method of comprehensive shape analysis, we detected cryptic SAM shape variation that identified QTL on six chromosomes. We found that Fourier transform shape descriptors and parabolic estimation measures are highly correlated and identified similar QTL. Analysis of shoot apex contours from 73 anciently diverged plant taxa further suggested that parabolic shape may be a universal feature of plant SAMs, regardless of evolutionary clade. Future high-throughput examinations of SAM morphology may benefit from the ease of acquisition and phenotypic fidelity of modeling the SAM as a paraboloid. [ABSTRACT FROM AUTHOR]

In seed plants, anthers are critical for sexual reproduction, because they foster both meiosis and subsequent pollen development of male germinal cells. Male-sterile mutants are analyzed to define steps in anther development. Historically the major topics in these studies are meiotic arrest and post-meiotic gametophyte failure, while relatively few studies focus on pre-meiotic defects of anther somatic cells. Utilizing morphometric analysis we demonstrate that pre-meiotic mutants can be impaired in anticlinal or periclinal cell division patterns and that final cell number in the pre-meiotic anther lobe is independent of cell number changes of individual differentiated somatic cell types. Data derived from microarrays and from cell wall NMR analyses allow us to further refine our understanding of the onset of phenotypes. Collectively the data highlight that even minor deviations from the correct spatiotemporal pattern of somatic cell proliferation can result in male sterility in Zea mays . [ABSTRACT FROM AUTHOR]

In this study, seven maize inbred lines representing different tropical, drought tolerant populations and two adapted temperate maize inbred lines were crossed in a half-diallel mating design to determine combining abilities. The genotypes were tested in wellwatered (WW) and managed water stressed (WS) conditions in 2013 and 2014. General combining ability (GCA) and specific combining ability (SCA) mean squares were significant for all investigated traits and demonstrated both additive and non-additive genetic effects in both conditions. Higher desired leaf rolling, leaf senescence, stomatal conductance and leaf chlorophyll content GCA effects of tropical inbreds under WS conditions showed the presence of the valuable allels related to drought stress. SCA analysis revealed that the best hybrids for water use efficiency and irrigation water use efficiency were tropical x temperate crosses. Stress tolerance index and drought resistance index identified G5 x G9, a tropical x temperate hybrid, as the most tolerant hybrid to drought. Our study suggests that tropical drought tolerant germplasm has the potential to contribute useful genetic diversity to temperate maize breeding programs. [ABSTRACT FROM AUTHOR]

A study was carried out in Central Bohemia to understand the effect of row spacing and stand density on plant morphology, productivity and quality of silage maize in two row spacing treatments (0.70 m and 0.35 m) at two stand densities (92,000 plants/ha and 110,000 plants/ha). The results of the study showed that row spacing and stand density had no effect on plant height or weight; however, significantly higher ear ratio and dry matter content was found in narrow rows at 110,000 plants/ha. It was observed that plant morphology was affected more by the interaction between row spacing and stand density than by a single effect of tested factors. Significantly higher dry matter yield was recorded at higher stand density, but there was no row spacing × stand density interaction. Row spacing had no impact on the whole plant neutral detergent fiber (NDF) content, crude protein of stover and starch content of ear, while narrow rows resulted in almost significantly higher stover NDF content. Our results suggest that narrow rows could be advantageous for maize morphology and quality in cases where higher stand density is applied. [ABSTRACT FROM AUTHOR]

Improving crop productivity through higher plant density requires a detailed understanding of organ development in response to increased interplant competition. The objective of this paper is thus to investigate the characteristics of organ development under increased interplant competition. A field experiment was conducted to investigate organ development across 4 maize plant densities i.e. 2, 6, 12 and 20 plants m–2 (referred to PD2, PD6, PD12 and PD20 respectively). In response to increased interplant competition, lengths of both laminae and sheaths increased in lower phytomers, but decreased in upper phytomers. Sheath extension appeared to be less sensitive to increased interplant competition than lamina extension. Extension of laminae and internodes responded to increased plant density as soon as onset of mild interplant competition, but did not respond any further to severe competition. Both lamina width and internode diameter were reduced due to a smaller growth rate in response to increased plant density. Overall, this study identified that organ expansion rate can be taken as the key morphological factor to determine the degree of interplant competition. [ABSTRACT FROM AUTHOR]

Maize is the 3rd major crop grown all over the world that fulfills the needs of millions of people. Various biotic and abiotic factors caused reduction in grain yield of maize, among them weeds show most adverse effects. Objective of this study was to develop glyphosate resistance maize for developing maize hybrids and synthetic varieties with high grain and fodder yield potential. Glyphosate is a broad spectrum herbicide and resistance of crop against the herbicide, allows post emergence application, which otherwise is impossible. Higher GTG crude protein (479.94µg/g) was recorded for CIL 194-975 plant. The plant CIL 194-1786 showed higher expression level of GTG protein, indicated that transformation efficiency was better for line CIL-194 than CIL-123. GTGene stably integrated to the genome of the maize lines CIL-194 and CIL-123, these transformed lines showed more ability to cope with herbicides as compared with non-transformed lines in greenhouse and field trials. The transgenic lines were sown in field and data was recorded for various morpho-physiological, grain, fodder yield and quality traits. Data was statistically analyzed to check significance of results at <0.05% probability level. It was concluded from heritability, genetic advance, stepwise multiple linear regression, principle component and factor analysis that the selection on the basis of grain yield, green fodder yield, stem diameter, cob weight, stomata conductance, chlorophyll contents, photosynthetic rate, cob length, grain protein, grain oil, embryo percentage and grain starch may be fruitful keeping in view as the major contributing traits to improve crop yield and production. It was suggested that the transgenic lines for glyphosate resistance may be used to develop transgenic hybrids and synthetic varieties with higher grain yield with high quality. [ABSTRACT FROM AUTHOR]

The aim of this investigation was to estimate the effects of crop density on the plant height (PH), ear height (EH), leaf number per plant (LN), ear length (EL), number of rows per ear (NRE), number of grain per row (NGR), number of grain per ear (NGE), grain weight per ear (GWE), cob weight (CW), 1000-grain weight (1000-GW), ear diameter (ED) and grain yield (GY) in staygreen maize hybrid Dijamant 6 (FAO maturity group 600). Three crop densities (51020 plants ha-1, 59524 plants ha-1 and 71429 plants ha-1) were tested. The field experiment was carried out during 2006 and 2007 at Srem region (Putinci: latitude 44° 59' 19" N; longitude 19° 58' 11" E). Plots were organized as completely randomized block system design in four replications. PH (284.3 cm), EH (119.9 cm), LN (13.9), EL (20.8 cm), GWE (232.5 g), CW (56.4 g), 1000-GW (378.4 g) and GY (13.56 t ha-1) were significantly higher in 2006 (favorable climatic conditions) than in 2007 (258.5 cm, 112.8 cm, 13.2, 17.9 cm, 192.9 g, 46.9 g, 232.7 g and 11.50 t ha-1, respectively). Increasing crop density significantly increased the PH, EH and GY, and significantly decreases the EL, NGR, NGE, GWE, CW and 100-GW. The crop density of 71429 plants ha-1 is the optimal for growing this hybrid in Srem region. On that crop density hybrid more efficiently used available resources and achieved the highest grain yield. [ABSTRACT FROM AUTHOR]

Studies that investigated the genetic basis of source and sink related traits have been widely conducted. However, the vascular system that links source and sink received much less attention. When maize was domesticated from its wild ancestor, teosinte, the external morphology has changed dramatically; however, less is known for the internal anatomy changes. In this study, using a large maize-teosinte experimental population, we performed a high-resolution quantitative trait locus (QTL) mapping for the number of vascular bundle in the uppermost internode of maize stem. The results showed that vascular bundle number is dominated by a large number of small-effect QTLs, in which a total of 16 QTLs that jointly accounts for 52.2% of phenotypic variation were detected, with no single QTL explaining more than 6% of variation. Different from QTLs for typical domestication traits, QTLs for vascular bundle number might not be under directional selection following domestication. Using Near Isogenic Lines (NILs) developed from heterogeneous inbred family (HIF), we further validated the effect of one QTL qVb9-2 on chromosome 9 and fine mapped the QTL to a 1.8-Mb physical region. This study provides important insights for the genetic architecture of vascular bundle number in maize stem and sets basis for cloning of qVb9-2. [ABSTRACT FROM AUTHOR]

Considering Iran and Azerbaijan to be origin countries in the Astara region, and in order to study the effects of salt stress on morphological and physiological characteristics, changes to eight maize cultivars were experimented on in three replications on the basis of randomized complete block design over three years. Cultivars included K3615/1, S.C704, B73, S.C302, Waxy, K3546/6, K3653/2, and Zaqatala-68, and they were cultivated in two pieces of land in Astara: one with normal soil and the other with salty soil. During the experiment, Na+ accumulation in leaves, chlorophyll a, chlorophyll b, leaf relative water content (LRWC), proline content, biomass per plant, harvest index, and grain yield per hectare were measured. Results from the experiment showed that, between locations (normal and saline) in most traits, significant differences were seen. And between varieties in all traits, significant differences were seen. The interaction between years and varieties for all traits was not significant. Comparison traits in different salinities showed that in most traits there are significant differences between genotypes. Proline content increased with increasing soil salinity. With increasing salinity, Na+ accumulation in leaves severely increased and the biggest accumulation was observed in S.C704. Maximum LRWC in B73 was measured in normal conditions. The highest amount of chlorophyll a, in normal conditions, was observed in S.C704 with 1.873 mg/g fresh weight of leaves, which was not significantly different from B73. Between chlorophyll a and chlorophyll b, Na+ and LRWC positive correlations were observed in non-stress conditions. Between chlorophyll a and chlorophyll b, yield per plant, and yield grain, significant positive correlations were observed in salty conditions. [ABSTRACT FROM AUTHOR]

Using eight maize varieties (Tiannuo 888, Yunnuo 6, Yunrui 999, Yunrui 6, Yunrui 47, Yunrui 88, Yunyou 105, Yuntianyun 2) as the research materials, this paper aimed to figure out the possible influence caused by repeated drought treatment. A pot experiment was conducted to investigate the changes in 13 phenotypic characters and physiological and biochemical indexes (plant height, fresh mass, root shoot ratio, POD activity, SOD activity) related to drought resistance, under two levels of water supply (repeated drought treatment and CK) at seedling stage of maize varieties, and evaluated drought resistance comprehensively by standard deviation coefficient allocation weighed method. The results showed that the survival rale, leaf area, plant height, shoot fresh mass, root fresh mass, shoot dry mass and root dry mass of seedling maize decreased at varying degrees after repealed droughl stress. However, the MDA molality, root shoot ratio, Pro content and soluble protein content increased under repeated drought stress. There were significant difference in morphological, physiological and biochemical indexes among different maize varieties. The drought resistances of different maize varieties successively were Yunrui 47 > Yuntianyu 2 > Yunyou 105 > Yunnuo 6 > Tianuo 888 > Yunrui 6 > Yunrui 999 > Yunrui 88. These results provide references for maize drought-resistant breeding and maize production. [ABSTRACT FROM AUTHOR]

This study was conducted in order to determine the effect of different previous crops and sowing dates on the grain yield and some other yield components of corn under typical Mediterranean climatic conditions during summer period of 2013 and 2014. The experiment was laid out in a split-plot design in the form of randomized complete blocks with three replications. The main plots were allocated to three sowing dates (Early Spring, Mid Spring and Late Spring) and sub-plots to previous crops (Vicia sativa, Vicia villosa, Lathyrus sativus, Trifolium resupinatum and Pisum arvense) and three different controls without previous crop (control-1: 100 kg ha-1 N; control-2: 200 kg ha-1 N and control-3: 0 kg ha-1 N). Corn grain yield, yield components (number of ears per plant, number of seeds per ear, ear length, ear diameter, 1000-grain weight) and plant height were assessed. The results showed that late planting date had a significantly negative effect on tested traits and second planting date (mid- spring) produced higher corn grain yield compared to the other dates. The highest corn grain yield (11011 kg ha-1) also occurred in control-2 (200 kg ha-1 N without previous crop) treatment and was significantly different from the other previous crop treatments with 100 kg ha-1 N and controls except Vicia villosa as previous legume crop of which corn grain yield was comparable with it. [ABSTRACT FROM AUTHOR]

The inhibitory effects on biological properties of maize (Zea mays L. saccharata Sturt) seeds treated with chlorantraniliprole (CAP) were examined under greenhouse conditions. Maize seeds were exposed to environmentally relevant doses (0.08, 0.1, 0.2, 0.3, 0.4, and 0.5 ppm) of CAP. On day 7 of germination, morphological, anatomical, and physiological responses were determined. The most devastating inhibitory effect on germination parameters of maize seeds was on coleoptile length (90%) in 0.5 ppm insecticide concentration. Increasing concentrations of CAP resulted in decreased stomata density, compared with control. Similar results were also observed in stomata dimensions. On the other hand, high concentrations of CAP led to phytotoxic effects on photosynthetic pigments such as chlorophyll a, chlorophyll b, and carotenoid. On the contrary, the amount of anthocyanin and proline increased in proportion to increasing dosages, despite a reduction in growth. The results showed that all investigated parameters (except for proline and anthocyanin) significantly decreased with increasing insecticide dosages, compared to control (p<0.05). The changes, particularly stomatal responses, and the amount of proline and anthocyanin on the leaves of the plants exposed to CAP stress, were determined as more sensitive parameters to detect insecticidal damage. [ABSTRACT FROM AUTHOR]

Fusarium temperatum and Fusarium subglutinans isolated from the Northwest region (NOA region) of Argentina were characterized using a polyphasic approach based on morphological, biological and molecular markers. Some interfertility between the species was observed. The phylogenetic analysis showed that the two species represented two clades strongly supported by bootstrap values. The toxigenic profile of the strains was also determined. F. temperatum strains were fusaproliferin and beauvericin producers, and only some strains were fumonisin B 1 producers. All F. subglutinans strains produced fusaproliferin but none produced beauvericin, indicating a potential toxicological risk from maize harvested in the NOA region of Argentina. This study provides new information about F. temperatum isolated from maize in Argentina. [ABSTRACT FROM AUTHOR]

Phytoremediation is promising, but depends on clearly understanding contaminants’ impact on plant functioning. We therefore focused on the impact of polycyclic aromatic hydrocarbons (PAH) on cultivated plants and understanding the impact of phenanthrene (PHE) on maize functioning ( Zea mays ). Cultivation was conducted under controlled conditions on artificially contaminated sand with PHE levels increasing from 50 to 750 mg PHE kg −1 . After four weeks, plants exposed to levels above 50 mg PHE kg −1 presented decreased biomasses and reduced photosynthetic activity. These modifications were associated with higher biomass allocations to roots and lower ones to stems. The leaf biomass proportion was similar, with thinner blades than controls. PHE-exposed plant showed modified root architecture, with fewer roots of 0.2 and 0.4 mm in diameter. Leaves were potassium-deplete, but calcium, phosphorus, magnesium and zinc-enriched. Their content in nitrogen, iron, sulfur and manganese was unaffected. These responses resembled those of water-stress, although water contents in plant organs were not affected by PHE and water supply was not limited. They also indicated a possible perturbation of both nutritional functioning and photosynthesis. [ABSTRACT FROM AUTHOR]

Six inbred lines were crossed according to incomplete diallel method. In this way fifteen hybrid combinations were obtained. Hybrid combinations derived from these parental components were used in this work. The objective of study was to estimate direct and indirect effects of five morphological traits on grain yield by the application of the simple coefficient correlation and path coefficient analysis. The trait number of leaves above the top ear with the value of 0.736 has the strongest direct positive effect on grain yield. Positive direct effects on grain yield were also observed for height to tassel base and plant height, while negative direct effects were observed for ear height and total number of leaves. As far as indirect effects were considered, a positive effect of the ear position height on yield over the total plant height stands out. The evaluation of the proportion of mutual effects of five observed morphological traits on grain yield, expressed by the coefficient of multiple determination (R2y12345) amounted to 0.7881. [ABSTRACT FROM AUTHOR]

Maize is highly sensitive to drought stress condition. A study was carried out in the glasshouse of the Department of Plant Breeding and Genetics, University of Agriculture Faisalabad, Pakistan during crop growing season of 2013 to access the potential genotypes screening against drought stress environment. The genotypes A239, A427-2, W10, A50-2 and A495 were found to be performed better under normal and drought stress conditions. Higher heritability and genetic advance was recorded for shoot length and shoot length under both irrigation conditions. Significant correlation was found among the traits root length, shoot length, dry root weight, fresh root weight, fresh shoot weigh and dry shoot weight. Significant correlation of root length and shoot length indicated the genotypes with higher root and shoot length showed drought stress resistance. Selection on the basis of root and shoot length may be helpful to improve maize yield under drought stress conditions. [ABSTRACT FROM AUTHOR]

Background and Aims A number of techniques have recently been developed for studying the root system architecture (RSA) of seedlings grown in various media. In contrast, methods for sampling and analysis of the RSA of field-grown plants, particularly for details of the lateral root components, are generally inadequate. Methods An integrated methodology was developed that includes a custom-made root-core sampling system for extracting intact root systems of individual maize plants, a combination of proprietary software and a novel program used for collecting individual RSA information, and software for visualizing the measured individual nodal root architecture. Key Results Example experiments show that large root cores can be sampled, and topological and geometrical structure of field-grown maize root systems can be quantified and reconstructed using this method. Second- and higher order laterals are found to contribute substantially to total root number and length. The length of laterals of distinct orders varies significantly. Abundant higher order laterals can arise from a single first-order lateral, and they concentrate in the proximal axile branching zone. Conclusions The new method allows more meaningful sampling than conventional methods because of its easily opened, wide corer and sampling machinery, and effective analysis of RSA using the software. This provides a novel technique for quantifying RSA of field-grown maize and also provides a unique evaluation of the contribution of lateral roots. The method also offers valuable potential for parameterization of root architectural models. [ABSTRACT FROM AUTHOR]

Current water scarcity is an emerging issue in semi-arid regions like Pakistan and cause of deterioration in productivity of crops to reduce crop yield all over the world. Silicon is known to be better against the deleterious effects of drought on plant growth and development. A pot study was conducted to evaluate the effect of Si nutrition (0, 50, 100 and 150 mg/kg) on the growth of a relatively drought tolerant (P-33H25) and sensitive (FH-810) maize hybrids. Two levels of soil water content were used viz. 100 and 60% of field capacity. Water deficit condition in soil significantly reduced morphological and physiological attributes of maize plants. Silicon application significantly improved the plant height, leaf area per plant, primary root length, dry matter of shoot and roots and plant dry matter, water relation and gas exchange characteristics of both maize cultivars under water deficit condition. Poor growth of drought stressed plants was significantly improved with Si application. The silicon fertilized (100 mg/kg) drought stressed plants of hybrid P-33H25 produced maximum (21.68% more) plant dry matter as compared to plants that were not provided with silicon nutrition. Nonetheless, silicon application (150 mg/kg) resulted in maximum increase (26.03%) in plant dry weight of hybrid FH-810 plants that were grown under limited moisture supply i.e., 60% FC. In conclusion silicon application to drought stressed maize plants was better to improve the growth and dry matter could be attributed to improved osmotic adjustment, photosynthetic rate and lowered transpiration. [ABSTRACT FROM AUTHOR]

To measure the contributions of parental inbreds per se and heterosis to the genetic gain of single- cross maize (Zea mays L.) hybrids, yield trials of 29 historically important hybrids used in China during 1964 through 2001 and their parental inbreds were conducted. Mean rate of genetic gain for single-cross hybrids when measured across all locations was 55 kg ha-1 yr-1; heterosis contributed 37 kg ha-1 yr-1 (67%) of yield gain. Inbred yields at stressed locations were exceptionally poor and may have inflated measurements of heterosis. At unstressed locations, heterosis contributed 5 kg ha-1 yr-1 (8%) and 16 kg ha-1 yr-1 (39%) or 10 kg ha-1 yr-1 (19%) when locations were combined. For individual characteristics, the highest percent heterosis was for kernel weight per ear (58.6%), corresponding to and emphasizing the historic goal in China of increasing yield on an individual plant rather than on a unit area basis. There are opportunities to further improve the productivity of Chinese maize by increasing inbred parent yields, increasing tolerances to stresses associated with higher planting densities, and also increasing the contribution of heterosis through optimal assignation of inbreds into complementary heterotic groups. [ABSTRACT FROM AUTHOR]

The present study was carried out to access the vigor of F1 hybrids for drought tolerance. Higher heritability and genetic advance were found for dry root weigh and total dry weight, strong genotypic correlation was found for dry root weight, dry shoot weight and total dry weight. Higher dry root and shoot weight and dry root-to shoot weight ratio was found for B-336 and Sh-139 × EV-347, B-336 × EV-347, EV-1097 × EV-340, EV-1097Q × B-316 and B-327 × EV-340. Higher heterosis and heterobeltiosis were found for F1 hybrids for dry root weight EV-1097 × EV-340 (190.476, 154.167), EV-1097 × Pop/209 (112.121, 94.444), dry shoot weight EV-1097 × Pop/209 (130.769, 114.286), dry root-to-shoot weight ratio EV-1097 × B-316 (115.519, 52.985) and B-27 × EV-340 (138.657, 102.344) and for total dry weight EV-1097 × Pop/209 (175.391, 108.333), EV-1097 × EV-340 (133.846, 85.366) respectively. The higher heterosis and heterobeltiosis for all traits indicated that hybrid vigor was higher due to which hybrids may be used for drought tolerance and to improve grain yield of maize. [ABSTRACT FROM AUTHOR]

Maize Research Institute "Zemun Polje" genebank maintains a collection of landraces grouped into 18 agro-ecological collected from ex-Yugoslavia territories. The application and comparison of different marker systems are important for the characterization and use of maize landraces in breeding program, as potential sources of desirable traits. In this study, 15 morphological traits, 7 RAPD primers and 10 SSR primer pairs were applied to i) to determine genetic distance between 21 maize dent landraces and ii) compare results obtained on morphological and molecular markers. Phenotypic analysis showed high level of heterogeneity between landraces. Higher level of genetic diversity was obtained with SSR than with RAPD. Genetic distance mean value for RAPD data was 0.35 i.e. for SSR 0.48. Based on the morphological traits and molecular markers, unweighted pairgroup method (UPGMA) analysis was applied for cluster analysis, using statistical NTSYSpc program package. Cluster analysis of morphological and molecular markers distances did not show the same population grouping. Better agreement with agro-ecological data was obtained with RAPD markers. Correlations between dissimilarity matrices for different types of markers were low. Data obtained in this work could be useful for further study of a larger number of landraces, and conservation of genetic resources and their genetic diversity. [ABSTRACT FROM AUTHOR]

Soft wheat milling quality assessment typically begins in the later stages of wheat breeding programmes and continues after cultivar release in commercial milling and processing operations. Near-infrared (NIR) hyperspectral (HS) image analysis, a technique that is gaining interest in food and pharmaceutical inspection research, was explored as an alternative procedure for milling quality evaluation. Three quality properties were studied, flour yield (the weight fraction of flour to whole grain), softness equivalent (a gauge of how easily flour is released from the kernel during break), and sucrose solvent retention capacity (SRC, related to arabinoxylans, which influence water absorption during dough mixing) because of their high degree of heritability and influence on soft wheat quality. NIR HS reflectance images (1000–1700 nm) of non-touching kernels were collected on more than 120 pure cultivars or advanced lines of soft red and white wheat. Five morphological properties (area, elliptical eccentricity and major and minor axis lengths, and ellipsoidal volume) and three spectral properties (principal component scores 1–3) were exhaustively examined in multiple linear regression models for each quality property and in nonparametric classification into low, medium, and high groups using texture properties (contrast, correlation, energy, and homogeneity) calculated from grey-level co-occurrence matrices of principal component scores images. Results indicated that softness equivalent exhibited the highest correlation with HS properties, while sucrose SRC had the lowest correlation. The combination of morphological and spectral properties produced better models than either property group alone. However, because of the inherent chemical and physical complexities of wheat, HS imaging will not be sufficient so as to replace actual pilot milling procedures. [ABSTRACT FROM AUTHOR]

Twelve local maize populations were evaluated at the experimental farm, University of Prishtina, Kosovo. The study was conducted to assess the magnitude of genetic variation in local maize populations for different morphological-physiological and chemical composition under field and laboratory conditions. Randomized complete block design (RCBD) with three replications was used for laying out the experiment. The results showed that there were significant differences for most morphological and physiological traits under study. The mean grain yield of all populations was 102.96 g plant-1. The protein and oil contents ranged between 11.53 to 9.43% and 4.23 to 4.87% respectively. The cellulose content varied from 6.03 to 6.37%. There were also big differences regarding phenotypic correlations. The present study revealed considerable amount of diversity among the local maize populations which could be manipulated for further improvement in maize breeding. [ABSTRACT FROM AUTHOR]

Drought is a major abiotic stress factor limiting crop growth, development and production worldwide. The objective of this study was to evaluate tolerance to osmotic stress of maize seedlings. More than 6,000 accessions from the Maize Research Institute gene bank were tested under controlled drought (at flowering) in Egypt, and afterwards in temperate climate (Serbia and Macedonia). Out of 41 drought tolerant accessions in the field, five inbred lines were chosen for laboratory testing, as well as one drought sensitive line. These genotypes were exposed to 4% polyethylene glycol-PEG (Mr 10000) for 24 h and 48 h. Nine-day-old seedlings compared to control conditions were analyzed in root and shoot length, fresh and dry weight and proline content. Results showed reduction in all parameters under stress, while only proline content increased in all PEG treated genotypes compared to control. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was to understand what factors influence the formation of different shapes of popped popcorn through the development of statistical models. Microwave popcorn popping was conducted across a range of microwave wattages (750–1240W) and oil additions (0–30%) using a set of three popcorn hybrids grown in three environments. After popping, expansion volume was measured and the relative proportion of different popped shapes was enumerated by visual characterization of popped flakes, namely: unilateral, bilateral, or multilaterally expanded. The percentage of flake morphologies varied from 1 to 24% unilateral, 20 to 55% bilateral, and 31 to 68% multilateral across all runs. The relative percentage of each shape was influenced by hybrid, growing location, corn:oil ratio, and microwave wattage. The proportion of unilateral flakes was positively correlated to oleic acid in the kernel and negatively correlated to kernel sphericity, while bilateral flakes were positively correlated to dietary fiber in the kernel. Expansion volume was positively correlated to occurrence of bilaterally expanded flakes and negatively correlated to unilateral shape. These data may support the development of new hybrids or varieties of popcorn that produce the most desirable amounts of popped shapes in order to optimize consumer liking or create differentiated products and market new usages for popcorn. [Copyright &y& Elsevier]

Maize (Zea mays ssp. mays) is among the world's most important and ancient domesticated crops. Although the chronology of its domestication and initial dispersals out of Mexico into Central and South America has become more clear due to molecular and multiproxy archaeobotanical research, important problems remain. Among them is the paucity of information on maize's early morphological evolution and racial diversification brought about in part by the poor preservation of macrofossils dating to the pre-5000 calibrated years before the present period from obligate dispersal routes located in the tropical forest. We report newly discovered macrobotanical and microbotanical remains of maize that shed significant light on the chronology, land race evolution, and cultural contexts associated with the crop's early movements into South America and adaptation to new environments. The evidence comes from the coastal Peruvian sites of Paredones and Huaca Prieta, Peru; dates from the middle and late preceramic and early ceramic periods (between ca. 6700 and 3000 calibrated years before the present); and constitutes some of the earliest known cobs, husks, stalks, and tassels. The macrobotanical record indicates that a diversity of racial complexes characteristic of the Andean region emerged during the preceramic era. In addition, accelerator mass spectrometry radiocarbon determinations carried out directly on different structures of preserved maize plants strongly suggest that assays on burned cobs are more reliable than those on unburned cobs. Our findings contribute to knowledge of the early diffusion of maize and agriculture and have broader implications for understanding the development of early preindustrial human societies. [ABSTRACT FROM AUTHOR]

In our country, the corn is cultivated from the time of the aboriginal ones and it constitutes a basic food in the human nutrition, of the livestock and the birds; it is thesecond cereal of importance and has high consumption preference for the population. In Cuba, six races of corn existwith a high diversity, which has been broadly studied. The present work was carried out in a sample of 106 local varieties, these local varieties were included conserved in situ inpeasants' properties and conserved ex situ. The objective of the study was to evaluate the degree of variability of the collection; using for it 16 characters. The obtained results allowed to detect the existence of variability in the sample. It was demonstrated that the evaluated collection of cornpresented variability due to the difference among genotypes, to the plurality of origins, handling and environmental conditions in that this cultivation is developed in Cuba. Also,in the studied collection, the variability of the evaluated characters is moderate, due to the selection that the peasantscarry out on them. The most variable characters were the incidence of Spodoptera frugiperda (Smith), height to the superior ear and weight of a hundred seeds. [ABSTRACT FROM AUTHOR]

This investigation was carried out with the objective of identifying and characterizing the races of maize, from the morphological and agronomic point of view, keeping in mind the strategy and status of conservation of the samples, as well as to establish the dynamics of races in the time, and to offer a working strategy for the evaluation and conservation of the genetic pool of maize crop in Cuba. In order to do that, they took the data of characterization of the ex situ collection, integrated by 92 accessions of the Cuban National Genebank,and 55 accessions evaluated in situ in two rural areas of Cuba.In both conservation forms, 14 characters were evaluated (nine continuous and five categorical ones) corresponding to the ear and the grain. They were analyzed using the strategy in two steps Modified Local WARD-method (MLM) with the statistical package SAS 9.0. In the accessions corresponding to the Cuban National Genebank, the Creole (Criollo) and Argentinean (Argentino) races stand out, and in the study carried out in the farms, races Tusón and Canilla were the most abundant. It was also showed that races Amarillo Reventador and Sweet (Dulce) were only present in the collection of the Cuban National Genebank. The characterized diversity found in the ex situ collection, is not entirety located in the in situ areas of the studied households, and vice versa, what suggests that it is necessary to collect in those areas, providing this way the enrichment of the ex situ collection and on the other hand to guarantee the conservation of the genetic pool of this crop in Cuba, through both forms. These elements demonstrate the necessity of the complementation in both conservation approaches. [ABSTRACT FROM AUTHOR]

Abstract: The primary objective of this study was to better understand how root morphological alteration stimulates N uptake in maize plants after root growth restriction, by investigating the changes in length and number of lateral roots, 15NO3 − influx, the expression level of the low-affinity Nitrate transporter ZmNrt1.1, and proteomic composition of primary roots. Maize seedlings were hydroponically cultured with three different types of root systems: an intact root system, embryonic roots only, or primary roots only. In spite of sufficient N supply, root growth restriction stimulated compensatory growth of remaining roots, as indicated by the increased lateral root number and root density. On the other hand, there was no significant difference in 15NO3 − influx between control and primary root plants; neither in ZmNrt1.1 expression levels in primary roots of different treatments. Our data suggested that increased N uptake by maize seedlings experiencing root growth restriction is attributed to root morphological adaptation, rather than explained by the variation in N uptake activity. Eight proteins were differentially accumulated in embryonic and primary root plants compared to control plants. These differentially accumulated proteins were closely related to signal transduction and increased root growth. [Copyright &y& Elsevier]

The spatial arrangement among plants affects both vegetative and reproductive meristem development. More axillary meristems develop at lower plant densities, which are associated with relatively high red:far-red light ratios (R:FRs; 645:735 nm). However, little is known about the effect of R:FR on corn (Zea mays L.) productivity. We conducted field research to determine the effect of early-season (VE-V7 corn) R:FR environments on corn morphology and productivity. Low, control, and high R:FR treatments were established by varying corn plant density (107,600, 53,800, and 3000 plants ha-1, respectively). At canopy closure (V7 corn), R:FR in the low, control, and high R:FR treatments was 0.23, 0.49, and 0.99, respectively. Each treatment was subsequently thinned to 3000 plants ha1 to avoid confounding effects of R:FR treatments and shading among plants. Grain yield per plant in the high R:FR treatment was 1.5 and 2.0 times greater than in control and low R:FR treatments, respectively, across years. Greater yield in the high R:FR treatment was attributed to greater tiller grain yield. Soil moisture and nutrient availability were similar among R:FR treatments. These results indicate that early-season R:FR was an important factor affecting corn productivity. Greater understanding of the R:FR-dependent pathway that controls axillary meristem development may provide direction for increasing productivity of elite nonprolific corn genotypes. [ABSTRACT FROM AUTHOR]

Abstract: The use of genotypes with improved performance for nitrogen (N) capture and use would be of great benefit through reducing production costs and pollution risks in maize cropping. The identification of morpho-physiological traits responsible for a better behavior in a target N environment is useful for cultivar selection, and become crucial for maize breeding improvement. This study analyzed, in a set of Argentinean commercial hybrids of maize, the grain yield (GY) variability in response to soil N availability at several locations representative of the main maize production region of Argentina during 2003–2004 growing season. The objectives of this work were to: (i) detect environmental groups for GY responses, (ii) identify morpho-physiological traits that were associated to winner genotypes in each detected environmental group, and (iii) assess genetic correlations between those traits. To generate more variation in soil N availability two N-fertilizer rates were applied in each experimental site (0 and 250kgNha−1, except for Balcarce where only 250kgNha−1 was tested). Morpho-physiological traits included in the analysis were related to N and radiation capture, use and partitioning, plant architecture, and leaf senescence. Grain yield components were also included. As expected, environment (E) effect explained the higher portion of GY variation (i.e., 82%), but genotype (G) and G×E interaction (GE) also significantly contributed (i.e., 9% each). Three environmental groups for GY were identified according to N availability. Morpho-physiological traits related to resource capture, use, and partitioning during the post-silking period are proposed as desirables for broad adaptation. In turn, a high N partitioning to grains after silking was associated with good hybrid behavior under high N availability and warm climate. On the other hand, a better grain yield performance when N became more limited appeared strongly related to an efficient canopy to sustain resource capture up to maturity. More studies are required in a wide range of environments to confirm identified traits and underlying physiological mechanisms. Nevertheless, our findings highlight the existence of differences in ideal plant-type for environments differing in N availability to be considered in maize breeding programs. [Copyright &y& Elsevier]

Nitrogen (N) and plant density are considered some of the most important factors affecting crop phenology (days to tasseling, silking, and maturity), morphology (leaves plant-1, seeds ear-1, ears 100 plants-1) and grain yield. The effects of plant density and N on phenology, morphology, and yield of maize (Zea mays L.) at Peshawar in northwestern Pakistan were evaluated during 2002 to 2004. The 2 × 3 × 6 factorial experiment was designed having two plant densities (60,000 and 100,000 plants ha-1) and three N levels (60, 120, and 180 kg N ha-1) applied to main plots, while six split application of N in different proportions were applied to subplots in two equal, three equal, three unequal, four equal, five equal and five unequal splits at sowing and with 1st, 2nd, 3rd, and 4th irrigation at two week intervals. All the phenological characteristics were significantly affected by year, plant density, rate and timing of nitrogen application. Year and plant density had no significant effect while rates and split application of N had significant effects on the leaf number plant-1 and seed number ear-1. Year, plant density and N rate had significant effects while N splits had no significant effects on the number of ears 100 plants-1 of maize. Significantly higher grain yield was observed under high plant densities, high N rate and split application of N, while its response to year effects was statistically non-significant. Tasseling, silking and physiological maturity were delayed and maximum grain yield was obtained from those plots maintained at higher plant density. Delaying in the phenological characteristics while increasing the number of leaves and seeds plant-1, and number of ears 100 plant-1 through high rate and split application of N results in maximum yield of maize at Peshawar. This study suggested that maize production can be maximized through high plant density and high N split application. [ABSTRACT FROM AUTHOR]

Heterosis often occurs in offspring derived from a cross between inbred or divergent parents and can be observed as the superior performance of these hybrids for a wide variety of characters. Heterosis was compared in maize lines at two ploidy levels, diploid and tetraploid, to gain a better understanding of the interaction of heterosis and ploidy level. Employing genetically identical diploid and tetraploid maize derived from four different inbred lines, we investigated heterosis for 11 morphological traits, including several plant height measures, as well as flowering time for both silks and anthers. We find that the heterotic response of a certain hybrid differs between diploid and tetraploid lines, and that the response at one ploidy cannot serve as a predictor for the other. Also, progressive heterosis was found for several of the characters in the tetraploid double-cross hybrid, which can have four different alleles at one locus, compared to the double-cross diploid hybrids, which can only possess two alleles per locus. Overall, the results indicate that the heterotic response of tetraploid maize lines differs significantly from that of the diploid. [ABSTRACT FROM AUTHOR]

• Background Maize (Zea mays) forms a complex root system comprising embryonic and post‐embryonic roots. The embryonically formed root system is made up of the primary root and a variable number of seminal roots. Later in development the post‐embryonic shoot‐borne root system becomes dominant and is responsible together with its lateral roots for the major portion of water and nutrient uptake. Although the anatomical structure of the different root‐types is very similar they are initiated from different tissues during embryonic and post‐embryonic development. Recently, a number of mutants specifically affected in maize root development have been identified. These mutants indicate that various root‐type specific developmental programmes are involved in the establishment of the maize root stock.• Scope This review summarizes these genetic data in the context of the maize root morphology and anatomy and gives an outlook on possible perspectives of the molecular analysis of maize root formation. [ABSTRACT FROM AUTHOR]

Se presenta una evaluación de la diversidad genética de variedades locales de maíz en la zona de La Palma, provincia de Pinar del Río, Cuba. Para el estudio se seleccionaron variedades de nueve productores (15 mazorcas por agricultor) las cuales fueron sembradas y luego comparadas en cuanto a sus características agromorfológicas. Los resultados confirman la importancia de los cultivos locales para el mejoramiento genético cultivar.

The article presents the author's view about the transformation of wild Teosinte into the first maize in relation to crucial observations. He remarks that the crucial observations by the wise lady on the morphological differences between the male tassel and the female ear of teosinte could offer key points on the transformation of teosinte into the first maize many years ago. He also comments on the scenario designed by the wise lady from her observations on tassel-ear differences in teosinte.