Ear Insertion Height Research Articles

Experimental unbalance: reflections on genetic parameters and corn selection gain

Genetic progress depends on the components of variance and genetic parameters. In this context, the objective of this work was to identify the maximum allowed percentage of experimental imbalance in the estimation of variance components, genetic parameters and selection gain in intervarietal corn hybrids. The experimental design used was randomized blocks, with 60 corn hybrids with three replications. Random subsets of data were created in order to express unbalance scenarios of the phenotypic matrix, we obtained 9 scenarios (0, 10, 20, 30, 40, 50, 60, 70 and 80% unbalance).Thus, the genetic variance of the paternal genitor, the genetic variance of the maternal genitor, additive variance, individual phenotypic variance, narrow-sense heritability of intervarietal additive effects for the paternal genitor were estimated, narrow-sense heritability of intervarietal additive effects for the maternal genitor, narrow-sense heritability, broad-sense heritability, genotypic variation coefficient between progenies and variation coefficient residual. Narrow sense heritability reveals high magnitude for the characters cob mass and hundred grain mass. Maternal effect is expressed through ear insertion height, ear grain mass, cob mass and diameter, number of rows, ear mass and length, and grain yield. The imbalance inflates the variance components and genetic parameters for the highlighted characters. It supports 10% imbalance in the data matrix without compromising the reliability of the estimates. Pronounceable selection gains are obtained for grain yield based on pressures of 1 and 5%. An unbalance of 10% is supported in the selection gain for cob mass, ear length and hundred grain mass.

Competitive response of maize against glyphosate-resistant Digitaria insularis and Eleusine indica

To optimize integrated weed management, it is essential to understand the competitive ability of maize hybrids with new traits when coexisting with the weed community. Thus, the aim of this study was to evaluate the competitive ability of the maize against E. indica and D. insularis weeds under greenhouse (controlled conditions) and in the field by additive and replacement series designs, with different densities for each condition. In greenhouse experiments, maize coexisting with E. indica resulted in negative relative growth for leaf area and shoot dry mass, indicating damage to both species. However, maize with D. insularis did not exhibit negative relative growth, suggesting a different interaction. The analysis of relative competitiveness and aggressiveness revealed significant values for maize with D. insularis, indicating a competitive relationship. In contrast, maize with E. indica showed non-significant values, suggesting a less competitive interaction. In field experiments, the full model and reduced models showed good fit to the data, with non-significant differences between them, indicating that the interference of these weed species on maize yield were similar. The Principal Component Analysis identified four principal components. For PCs 1 and 2, chlorophyll-related variables exhibited a high relative contribution, showing a positive correlation with cases involving high density of D. insularis. Variables related to ear insertion height, plant height, stem diameter, and stand of plants had greater relative importance for PC 1, especially for cases with higher density of E. indica. This highlights the resilience of maize to competitive conditions and suggests that its capacity for rapid growth in height makes this crop effective in competition for light, even against other C4 species.

INOCULAÇÃO E APLICAÇÃO DE DIFERENTES DOSES DE Azospirillum brasilense E SUA INFLUÊNCIA NO DESENVOLVIMENTO DA CULTURA DO MILHO

Benefits in grain productivity, with low economic cost, ease of application, without causing toxic damage to the environment and with high potential for crop response, are target points in research involving the cultivation of corn. In this context, the present study aimed to evaluate the effect of inoculation of Azospirillum brasilense on the vegetative structures of the corn crop, envisioning an increase in the development of the plant. The experimental design used was completely randomized, with six treatments and four replications, totaling 24 experiments. Seeds were inoculated with A. brasilense in different doses of the commercial product (0 - 1000 mL), where the plant height (AP), ear insertion height (AIE), stem diameter (DC), total number of leaves (NTF) and number of leaves below the first ear (NFAE), were evaluated. The inoculation of corn seeds based on A. brasilense strain Ab-V5 promoted influence on some biometric variables, with an increase in the total number of leaves (NTF), plant height (AP) and height of ear insertion (AIE) for the evaluated hybrid, resulting in increments in its vegetative development. The dosage of 549 mL per hectare was considered as favorable to result in greater amounts of total leaves (NTF) in the plant, according to the adjustment of the proposed model. The results emphasized that inoculation with this strain is a valid technique and is increasingly used by farmers, and its study is a contributing factor for improvements in agronomic parameters.

Doses and application timing of boron on the agronomic characteristics of corn

Corn cultivation holds great economic importance in Brazil, as it is grown throughout the country, covering approximately 21.5 million hectares annually, with a production of 113 million tons in the 2021/2022 harvest. However, crop production is directly linked to plant nutrition, and boron (B) is one of the essential micronutrients for plant development. Its deficiency imposes limitations on Brazilian agricultural crops. Therefore, the objective of this study was to evaluate the vegetative and productive characteristics of corn in response to the application of different doses of boron at different application timings. The experimental design used was completely randomized, in a 3x5 factorial scheme, with 4 replications, consisting of the combination of 5 doses of B (0, 0.5, 1, 2, and 4 kg ha-1) applied in the sowing furrow and at the V4 and V7 phenological stages. Plant height, first ear insertion height, stem diameter, number of rows per ear, number of grains per row, number of grains per ear, ear weight, grain weight per plant, and 100-grain weight were evaluated. No significant differences were observed between the doses and/or timing of boron application in the hybrid corn used in this study.

Agronomic performance of green corn at different sowing times and nitrogen doses

The present study aimed to identify the best sowing time and the best nitrogen dose in topdressing of the corn crop for "green ear" consumption. The experiment was conducted between October 2018 and June 2019 in a commercial crop, in Ipameri, Goiás, Brazil. The soil in the experimental area is classified as dystrophic Red-Yellow Latosol with clayey texture. The experimental design used was the randomized blocks, in a 5 x 5 factorial scheme, with five sowing times [1st (10/19/2018); 2nd (11/29/2018); 3rd (01/08/2019); 4th (02/18/2019) and 5th (03/28/2019)], implemented with 40 days intervals, after the first sowing, and five nitrogen doses (0, 50, 100, 150, and 200 kg ha-1), with four replicates. The following factors were evaluated for each sowing time: relative chlorophyll index, leaf dry mass, leaf nitrogen content, plant height, first ear insertion height, ears diameter and length, the total yield of ears with husks, the yield of commercial ears without husks and grain yield. The data were submitted to the analysis of variance (F-test). The sowing times and nitrogen doses in topdressing influenced the leaf nitrogen content, relative chlorophyll index, leaf dry mass, yield, and most of its components. Thus, it can be indicated that the best time for sowing corn for fresh consumption is in October (1st sowing time), and the estimated nitrogen dose in topdressing to obtain the maximum yield is 160 kg ha-1 of nitrogen.

Cinco ciclos de seleção recorrente intrapopulacional em progênies de meioirmãos de milho fresco

ABSTRACT Fresh corn is a highly appreciated vegetable in Brazil; this crop has high added value and profitability when compared to dry corn. Despite the consumer market demand for quality, cultivars are not launched every crop season and there is a small number of cultivars available to growers. This denotes a need for breeding programs focused on generating information and genotypes that can occupy this market niche. The objective of this work was to evaluate the progress of five cycles of intrapopulation recurrent selection in half-sib progenies of fresh corn, in the southwest region of Goiás. A randomized block experimental design was used, with evaluation of 64 progenies of corn half-sib progenies and selection intensity of 30% per cycle, with three replications, in the 2011-2012, 2013-2014, 2015-2016, 2017-2018, and 2020-2021 summer crop seasons. The half-sib progenies of fresh corn exhibited genetic variability through intrapopulation recurrent selection in the different selection cycles, which is still promising for further selections after five cycles, with evaluation of 64 progenies per cycle. The base population from crossings between hybrids for tropical and temperate climates showed to be promising for increasing the genetic base of fresh corn populations, with satisfactory gains over the five cycles, presenting mean heritability between the cycles of approximately 78.9% for relative chlorophyll index, 62.2% for plant height, 75.1% for ear insertion height, 70% for ear diameter, 56.6% for ear length, 71.4% for unhusked ear yield, and 71% for marketable ear yield.

Bioestimulantes aumentam o crescimento e a produtividade do milho de segunda safra

ABSTRACT The use of biostimulants in second-crop maize (Zea mays) can promote higher physiological activity in plants, resulting in higher grain yield. This study aimed to evaluate the effects of phytohormones and nicotinamide on growth and yield traits of second-crop maize. The statistical design used was a randomized block design arranged in a factorial scheme with two doses of phytohormones (0 and 500 mL ha-1) × five concentrations of nicotinamide (0, 200, 400, 600, and 800 mg L-1) with four replications. The use of biostimulants favored all variables evaluated for the maize crop. The isolated use of phytohormones and nicotinamide promoted grain yields of 6089.6 and 6242.5 kg ha-1, respectively, representing gains of 6.0 and 11.6%, respectively, compared with the control. The application of 800 mg L-1 nicotinamide resulted in the highest maize grain yield. The use of phytohormones and nicotinamide, isolated or associated, was favorable for the growth characteristics and grain yield of second-crop maize. A synergistic effect was noted between phytohormones and nicotinamide on the first ear insertion height and number of rows per ear.

Agronomic characteristics and yield of corn after inoculation with Bacillus amyloliquefaciens

Corn is one of the most important crops in Brazil and, due to its physiological characteristics, it has a high productive potential and high nutritional quality, for animal and human nutrition. Therefore, this work sought to evaluate Bacillus amyloliquefaciens subsp. plantarum FZB42 on agronomic characteristics and yield of corn crop. A randomized block design was used, with six doses of B. amyloliquefaciens subsp. Plantarum FZB42 (0.0; 2.5; 5.0; 7.5; 10.0, and 12.5 mL kg-1 seeds) and four repetitions, totaling 24 experimental units. The study was conducted in the experimental area of annual crops of the Instituto Federal de Educação, Ciência e Tecnologia do Sul de Minas Gerais (Federal Institute of Education, Science and Technology of the South of Minas Gerais — IFSULDEMINAS), Muzambinho Campus, in the 2017/18 agricultural year. The agronomic evaluations were: plant height, upper ear insertion height, culm diameter, leaf nitrogen content, forage fresh mass, incidence of Fusarium in the ear, number of rows per ear, number of grains per row, mass of 1000 grains, and yield. The nutritional evaluations performed were: crude protein, ash, ether extract, crude fiber, fiber in acid detergent, and fiber in neutral detergent. In summary, the inoculation of B. amyloliquefaciens subsp. Plantarum FZB42 in corn seeds, regardless of the dose applied, did not interfere with the agronomic characteristics and nutritional quality of corn silage.

Morphoagronomic characterization and production gain after two mass selection cycles in Nawa Sheki landraces maize originated from the Western Brazilian Amazon

Intensive breeding and artificial selection of the desired traits in maize landraces through domestication have created modern maize, which needs a great technological contribution for optimal productive development. However, the narrowing of the genetic bases of maize made it difficult for traditional farmers to access productive genetic material that maintains the genotypic and phenotypic diversity capable of ensuring productive sustainability. Thus, objective of the study was to evaluate the variability and production gain in morphoagronomic characters of Nawa Sheki landraces maize after two mass selection cycles. The work was carried out in the experimental area of the Federal University of Acre, where two cycles of mass selection were applied on variety Nawa Sheki, in periods 2018/2019 and 2019/2020. The characteristics evaluated were: plant height, ear insertion height, ear length, ear diameter, number of rows of grains, number of grains per row, ear mass and grain mass. Data were submitted to descriptive analysis, with presentation of the histogram of frequency, asymmetry, kurtosis and Shapiro-Wilk test for the general population in both cycles. For the selected population, the following were obtained: mean, coefficient of variation, amplitude, minimum and maximum values and population variance in each cycle. The genetic parameters were selection differential for both cycles, production gain with selection and realized heritability of the first cycle. The choice of individuals in both cycles of mass selection was based on the ranking of the best values of the evaluated characteristics. The two cycles of mass selection provided high variability in the traits with the presence of superior phenotypes. Still, mass selection stabilized values for plant height, ear insertion height, followed by production gains for number of grains per row and ear mass.

Seed treatment with magnesium nanoparticles alters phenology and increases grain yield and mineral content in maize

Magnesium is an essential macronutrient for maize crop and its efficiency of absorption and utilization by plants can be improved when used in the form of nanoparticles. The objective of this work was to evaluate the efficiency of different sources of magnesium oxide via seed treatment in the agronomic performance of maize. The experiments were carried out under field conditions in three locations in the state of Santa Catarina, Brazil. In all experiments, the P4285HYR-hybrid maize seeds were used, with three sources of magnesium: MgO-NPs, MgO@C-NPs and Mg(NO3)2; and six concentrations: 0 (control); 37.5, 75, 150, 300 and 600 mg L-1. The following variables were analyzed: SPAD reading, NDVI, plant height, ear insertion height, number of grains per ear, grain moisture, thousand grain weight, yield and quantification of Mg, Ca, P and K in the grains. The results showed that the seed treatment with magnesium oxide alters the V4 and V5 phenological stages (fourth and fifth developed leaves), shortening the plant life cycle by four to five days (P<0.05). All applied concentrations increased maize grain yield, with greater improvement in the order of 38% with 150 mg L-1 of MgO-NPs and 57% with 300 of MgO@C-NPs in comparison to control, respectively. The use of 75 and 150 mg L-1 of magnesium nitrate increased grain yield by only 2.3% and 6.6%, respectively, when compared to the control. The P>K>Mg>Ca levels in the harvested grains were increased by seeds treated with Mg. The results were significantly influenced by the nanoparticles, when comparing with conventional Mg nitrate or with the control. Therefore, it was concluded that the use of magnesium nanoparticles via seed treatment is a viable strategy to increase maize grain yield.

Variation of plant height and ear insertion height traits in short-season maize hybrids under the optimal and late sowing dates

Topicality. In light of the intensification of agriculture towards more rational utilisation of land resources and the growing season, given the importance of stubble and postcut fodder maize crops in fodder production and maize adaptability to the conditions of the Steppe zone, it is important to study the growth processes of maize under late sowing. Namely, the study of the influence of late sowing date on such traits as plant height and insertion height of the first productive ear for early ripening hybrids, the share of which in maize grain production is increasing. Purpose. To establish the most stable hybrid combinations by studying the variability of plant height and ear insertion height in early ripening maize hybrids under two sowing dates. Methods. Hybridization was used for developing hybrid material; laboratory and field method – to determine morphobiological traits of maize hybrids; measuring weight - to determine metric traits of plants; mathematical and statistical method – to determine the reliability of results, indicators of trait variability, and the correlation of traits. Results. The study of early ripening maize hybrids developed by crossing the most common germplasms under two sowing dates revealed that hybrids of heterotic models Iodent×Flint and Iodent×Mix had stably high values of the plant height trait at both sowing dates; hybrids of heterotic models Iodent×Flint and Iodent×Mix and Mix×Flint had stably high values of the insertion height of first productive ear at both sowing dates. Conclusions. We have identified the hybrid combinations DK4173SVZM×DK367, DK4172×DK367, MS381MV×DK367, MS555×DK367 (heterotic model Iodent×Mix), and DK4173SVZM×DK2073 (heterotic model Iodent×Flint), which were characterised by stably high values of the plant height trait, as well as the hybrid combinations DK4172×DK4538 (heterotic model Iodent×Flint), DK4172×DK367 (heterotic model Iodent×Mix), and DK2659×DK4538 (heterotic model Mix×Flint), which were characterised by stably high values of the insertion height of first productive ear at both sowing dates. The correlation between plant height and the ear insertion height of maize hybrids was confirmed for both sowing dates in all heterotic models studied. Key words: common maize, breeding, prematurity, plant height, ear insertion height, sowing dates, line, single-cross hybrids

EFFECT OF WATER SUPPLY AND SOWING DATES ON CORN YIELD OF HYBRIDS GROWN DURING OFFSEASON

This study aimed to evaluate the effect of water supply and sowing time on yield and yield components of two corn hybrids grown during offseason in the region of Dourados-MS, Brazil. The experimental design was randomized blocks in sub-divided plots, with four replications. In the main plot, two sowing dates were defined (2013 crop year: February 27 and March 27; and 2014 crop year: March 18 and April 5). In subplots, irrigation management systems were defined (irrigated and rainfed). Hybrids AS 1555 and AS 1590 were grown in the sub-plots. The parameters evaluated were plant height, ear insertion height, stem diameter, ear length and diameter, 100-grain weight, and grain yield. Regardless of irrigation and hybrid used, sowing time significantly affected corn yield, which responded to climate changes throughout crop cycle. Water supply increased corn yield, with the highest value being of 9338 kg ha-1 (156 bags ha-1) and obtained when irrigated AS 1555 hybrid was sown on February 27, 2013.

Effect of microdose chemical fertilization method on soil chemical properties and productivity of maize (Zea mays L.) in West-Central Senegal

This study was conducted in West-Central Senegal (Thies region) during two cropping seasons (2018 and 2019) to evaluate the effect of different doses of chemical fertilizer on soil chemical properties and the productivity of maize. Four treatments consisted of T0 (absolute control), RD (Recommended dose= 200 kg ha-1 NPK and 150 kg ha-1 urea), M1 (microdose 1= 41.66 kg ha-1 NPK and 41.66 kg ha-1 urea i.e. 0.5 g hill-1 NPK and 0.5 g urea), M2 (microdose 2= 83.33 kg ha-1 NPK and 41.66 kg ha-1 urea i.e. 1g hill-1 NPK and 0.5 g urea) and four maize varieties Gwana and Soror (composite varieties), Pan12 and Pan53 (hybrid varieties) were arranged in a split plot design with four replications. On average height of ear insertion was significantly increased with fertilizer microdosing. In 2018, microdose M1 achieved 89% and 26% of the grain yields recorded from T0 and RD, respectively. In line with grain yields, the amounts of soil elements exported in 2018 were higher in microdose in comparaison with RD and T0. A progressive decrease in soil pH and potassium is observed. Soil nitrogen decreased in 2018 but it increased in 2019, while an opposite trend was observed for soil phosphorus. The microdose technique was economically profitable with value-to-cost ratio of 9 and 4.47 for M1 and M2, respectively. It is concluded that the positive effect of fertilizer micro-dosing in improving maiz production depend on year, and on the better exploitation of soil nutrients.

PLANTING FERTILIZATION AND NITROGEN DOSES IN TOPDRESSING IN SECOND-CROP CORN

The present study aimed to evaluate the influence of fertilization formulated at planting and doses of nitrogen in topdressing on the yield components of second-crop corn. The experiment was conducted between March and June 2018 on the farm of the State University of Goiás, University Unit of Ipameri-GO. The randomized block design, arranged in a 3 x 5 factorial scheme with four replications, was used. Three fertilizer formulations at planting (06-22-12; 08-20-15 and 06-22-12 + 2% organic carbon) and five doses of N (0, 50, 100, 150 and 200 kg ha-1) in topdressing were evaluated. Leaf nitrogen content, fresh and dry mass of leaves, plant height, stem diameter, first ear insertion height, length and diameter of ears, 1000-grain weight, the mass of plants per hectare, extraction of nitrogen, and grain yield were assessed. Given the results, NPK formulated fertilizers can be used indifferently to grow second-crop corn. Nitrogen doses in topdressing have satisfactory results up to the estimated rate of 135 kg ha-1 for the cultivation of second-crop corn.

APTITUDE OF IMPROVED HALF-SIB PROGENIES FOR GREEN CORN PRODUCTION

The objectives of this study were to evaluate improved half-sib progenies with an aptitude for green maize production in terms of agronomic adaptation and ear yield potential. The experiment was installed in the 2017/2018 harvest without a randomized block design with three replications. Two commercial controls (variety CatiVerde 02 and hybrid AG 1051) were used with 98 half-sib progenies. The genotypes were formulated to optimize the agronomic characteristics of plant height, male and female cycles, and ear insertion height. At stage R3 (milky grain), ears were harvested to evaluate commercial ear length, commercial ear diameter, the total number of ears, the total number of commercial ears, the percentage of commercial ears, the average mass of commercial ears, and productivity of commercial ears. From the analysis of variance, the genetic parameters were estimated by the mathematical expectation of the mean squares of the sources of variation. A principal component analysis (PCA) was performed, followed by genotype grouping by genetic dissimilarity using the UPGMA method. The resulting genetic parameters demonstrated high variability among progenies, indicating potential genetic gain with artificial selection. The PCA enabled 30 half-sib progenies to be selected, highlighting the P-32, which stood out with an average yield of 14,230 kg ha-1. The UPGMA clustering method revealed five genetically different groups and eight divided progenies. The results clearly demonstrated the existence of favorable genetic variability among the progenies of corn half-sibs, making them well suited to green corn production for fresh consumption.

Agronomic response of a maize hybrid (Zea mays L.) at different planting densities

The experiment was carried out at the “La María” Campus of the State Technical University of Quevedo, located in the Mocache canton, province of Los Ríos. This consisted of the establishment of experimental lots of the simple maize hybrid called “Centella”, classified as high yielding and medium segmentation, subjected to different planting densities, which corresponded to the following treatments: T1 (60 x 25 cm), T2 (70 x 25 cm) and T3 (80 x 25 cm). A Completely Randomized Design (CRD) with five replications was used to evaluate them; the comparison between means was carried out using Tukey's test (P≤0.05). The variables studied were: plant height (cm), stem diameter (cm), ear insertion height (cm), number of grain rows in the ear, ear length (cm), ear diameter (cm), weight of 100 grains, grain yield (kg/ha), phenology and economic analysis. The treatments showed statistical similarity in all agronomic performance variables and most of the productive parameters, except for grain yield, where T1 stood out over the other treatments with a record of 9282.21 kg/ha.

Nitrogen response of two corn cultivars grown alone or intercropped in a soybean succession system in the Brazilian cerrado

The most widely used production systems in the Cerrado region are soybean (Glycine max)-corn (Zea mays) and soybean-corn intercropped with ruzigrass [Urochloa ruziziensis (Syn. Brachiaria ruziziensis)]. Thus, these systems may require a higher supply of mineral nitrogen (N) fertilizer. Therefore, the objective of this study was to evaluate the agronomic traits of two corn cultivars grow in the second-crop harvest in different environments, production systems, and N application rates in an Oxisol in the Cerrado region of Mato Grosso do Sul. The experimental design was a randomized block arranged in a split-split plot with three replicates. Plots consisted of two environments (UFMS 1 and UFMS 2), subplots consisted of two production systems [corn alone (monoculture) or corn intercropped with U. ruziziensis, and sub-subplots of five N application rates in topdressing (0, 40, 80, 120, or 160 kg N/ha). Urea was used as the source of N (45% N), and it was applied 30 days after emergence (DAE). Two corn cultivars (NS50 and Invictus Viptera 3) were used. During the flowering period of corn (i.e., after the emergence of female inflorescence), the relative chlorophyll index, leaf N concentration, plant height, and ear insertion height were recorded. At physiological maturity, the ear insertion height, ear length, number of grain rows per ear, number of grains per row, ear diameter, mass of one thousand grains, and grain yield were measured. The corn grain yield is lower in the system intercropped with U. ruziziensis when compared to the cultivation of corn alone (monoculture). In addition, the environment with greater soil base saturation and N availability (UFMS 2) results in a distinct response for the corn cultivar used; thus, a greater grain yield is expected from cultivar Viptera 3 in this environment. The maximum agronomic efficiency for corn grain yield is obtained with 102 to 123 kg N/ha for the Viptera 3 and NS50 PRO cultivars, respectively.

Híbridos duplos experimentais de milho verde cultivado sob baixa e alta disponibilidade de fósforo

ABSTRACT A serious problem in fresh corn growing regions is the low availability of phosphorus (P), especially in the Cerrado (Brazilian Savanna) biome. This study aimed to evaluate the performance of experimental double hybrids of fresh corn intended to in natura consumption grown under low and high P availability. A randomized blocks experimental design was used, in a 2 × 21 factorial arrangement, consisting of two P availabilities (37.5 and 75 mg dm−3 of P2O5) and 21 corn hybrids, with 9 replications. The following variables were evaluated: ear insertion height, plant height, male and female flowering, ear length and diameter, grain weight, husked and unhusked ear weight. The best quality and yield for the corn market focused on in natura consumption were observed for the experimental double hybrids DH94 and DH102 under low P availability and for DH71 and DH81 under high P availability. The DH81 hybrid performs better for the consumer market, regardless of the P availability, and, therefore, has versatility and aptitude for this market and for different technological levels.

Sample size for canonical correlation analysis in corn

The canonical correlation analysis has been successfully used in many areas aiming to extract important information from a pair of data sets. Thus, the objective of this work was to determine the sample size (number of plants) required to estimate the canonical correlations in corn characteristics. Six characteristics were measured in 361, 373, and 416 plants, respectively, of the single, three-way and double cross hybrids of the 2008/2009 crop year and in 1,777, 1,693, and 1,720 plants, respectively, of the single, three-way, and double cross hybrids (2009/2010 crop) (six cases). The canonical correlation analyses were carried out between characteristics group of the plant architecture (plant height at harvest and ear insertion height) versus grain production (hundred grains mass and grains mass per plant) (scenario 1), and dimensions of ear (ear length and ear diameter) versus grain production (hundred grains mass and grains mass per plant) (scenario 2). The sample size (number of plants) for the estimation of canonical correlations was determined by resampling with replacement and application of the model linear response with plateau. Measuring 270 plants is sufficient to estimate the canonical correlation between groups with two characteristics in each group for corn. This sample size can be used as reference for reliable canonical correlation analysis.

INFLUENCE OF TIMES AND METHODS OF BLACK OAT MANAGEMENT ON CORN DEVELOPMENT AND YIELD

This study aimed to evaluate the influence of management times and methods of black oat straw on corn crop development and yield under a no-tillage system for two crop seasons. A randomized block design was used with twelve treatments. They were arranged in a 3 x 4 factorial scheme with four replications, consisting of a combination between three methods (crushed, rolled, and desiccated) and four times (0, 10, 20, and 30 days before corn sowing). Black oat was evaluated for dry matter, while corn was for plant final population, height, stem diameter, ear insertion height, ear diameter, ear length, grain number per row, 1000-grain weight, and grain yield. All management methods and times interfered with corn crop yield components, but not all influenced final production. The method with the largest final corn population was not the same with an improved ear development. Such findings, however, may not be the same under highly favorable weather conditions.