Altamir Frederico Guidolin

Incremento na densidade de plantas: uma alternativa para aumentar o rendimento de grãos de milho em regiões de curta estação estival de crescimento

The development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.^lpt^aO surgimento de novos cultivares de milho, de ciclo mais curto, estatura reduzida, menor numero de folhas e folhas mais eretas aumentou o potencial de resposta da cultura a densidade de plantas. Essa tendencia pode ser acentuada nos planaltos do Sul do Brasil, que apresentam temperatura media nos meses mais quentes inferiores a 22°C, o que resulta em menor estacao estival de crescimento. Quatro experimentos foram conduzidos objetivando avaliar a viabilidade de se trabalhar com densidade de plantas maiores do que as atualmente recomendadas para esta regiao, como uma forma de aumentar o rendimento de graos. Nestes experimentos, submeteram-se os hibridos Cargill 901 e XL 370 a uma populacao que variou de 37.000 a 100.000pl ha-1, sob diferentes situacoes de manejo. Em tres dos quatro experimentos realizados, o uso de densidade de plantas superior a 60.000plha-1 maximizou o rendimento de graos. A maior competicao intraespecifica verificada nas densidades mais elevadas nao reduziu drasticamente o numero de espigas por planta, o que contribuiu para a melhor adaptacao da cultura a densidades elevadas. Dessa forma, para locais com estacao estival de crescimento mais curta, o uso de cultivares precoces, de menor porte, pode ser acompanhado pelo incremento na densidade para valores compreendidos entre 65.000 e 80.000pl ha-1. Isso e possivel desde que se tenha bom nivel de fertilidade no solo, boa disponibilidade hidrica e cultivares resistentes ao acamamento.^len^aThe development of earlier hybrids, with shorter plant height, lower leaf number and upright leaves has increased maize potential adaptability to withstand high plant densities. This trend may be emphasized on the high lands of Southern Brazil due to their mild Spring and Summer temperatures and shorter maize growing season. Four trials were carried out, aiming to investigate the viability of using higher than recommended plant populations, as an alternative to improve grain yield. The maize hybrids Cargill 901 and XL 370 were evaluated at several plant populations, ranging from 37000 to 100000pl ha-1, under different management situations. In three out of four experiments, plant populations above 60000pl ha-1 maximized grain yield. The greater competition among individuals verified at high plant populations did not decrease substantially the number of ears per plant, which contributed to improve maize adaptation to high plant densities. Therefore, for regions with a short growing season, the use of early small stature maize hybrids may be accompanied by an increment in plant population up to a value varying between 65000 and 80000pl ha-1. This is conceivable as long as there is adequate soil fertility, water availability and stem lodging resistant genotypes.

Influência da redução do espaçamento entre linhas no rendimento do milho em regiões de verões curtos

(2) Abstract†n†The interest in reducing maize row spacing in the short growing season regions of Brazil is increasing due to potential advantages such as higher radiation use efficiency. This experiment was conducted to evaluate the effect of row spacing reduction on grain yield of different maize cultivars planted at different dates. The trial was conducted in Lages, in the State of Santa Catarina, Brazil, during 1996/97 and 1997/98 growing seasons, in a split-split plot design. Early (October†1 st ) and nor- mal (November†15) planting dates were tested in the main plot; two morphologically contrasting culti- vars (an early single-cross and a late double-cross hybrids) were evaluated in the split plots and three row widths (100, 75 and 50†cm) were studied in the split-split plots. The reduction of row spacing from 100 to 50†cm increased linearly maize grain yield. The yield edge provided by narrow rows was higher when maize was sown earlier in the season. Differences in hybrid cycle and plant architecture did not alter maize response to the reduction of row spacing.

A desuniformidade de emergência reduz o rendimento de grãos de milho

High maize grain yields are related to a fast, complete and regular plant emergence. This experiment was carried out in Lages, SC, Brazil, with the objective of evaluating the effects of an uneven plant emergence on maize grain yield at different plant populations. A split plot design was used, with the main plots disposed in randomized complete blocks. Four plant populations, equivalent to 40,000, 60,000, 80,000 and 100,000 pl.ha-1 were tested in the main plots. Different levels of unevenness in plant emergence were analyzed in the split plots by varying the sowing dates of adjacent hills inside each as it follows: 1 - even emergence (0-0-0-0); 2 - unevenness of 12 days (0-12-0-12); 3 - unevenness of 19 days (0-19-0-19); 4 - unevenness of 12 and 19 days (0-12-19-0-12-19). The increase in plant population up to 76,500 pl.ha-1 enhanced grain yield to 12,900kg.ha-1. At this plant population, the difference in yield grain per hectare among treatments with even and uneven emergence was nearly 2,900kg. This indicates that under similar productivity levels replanting maize may be on economically viable option. Besides reducing grain yield, uneven emergence also limited maize response to the increment in plant population.

Análise de trilha. I: análise do rendimento de grãos e seus componentes

Thirty two bean accesses (Phaseolus vulgaris L.) were evaluated for the influence of eight characters of agronomic importance the production of grains for unit of area, in Lages/SC. The experiment, in randomized blocks with four repetitions, was conducted during the period off-season in the agricultural year of 1996/97. This work aimed estimating the degree of association between grain yield and its secondary components. The first group of variables (primary) was constituted by the number of grains per pod, number of pods per plant, weight of a thousand grains and the population of plants (POP). The second group (secondary), was constituted by the number of days between emergence and flowering (FL), number of days between emergence and harvesting point (MC), plant stature (EP) and the height of first pod insertion (PIL). For the analysis of the trail coefficient, the direct and indirect effects of primary characters NLP and PMG were characterized and evaluated, revealing the large direct effects associated with the high correlation. The NLP was highly influenced by plants of shorter cycle and higher stature. The trail coefficients allow to point out that the largest direct effects on the yield of grains NLP are mainly associated to PMG, NGL and cycle of the plant.

Incidência e severidade de doenças de quatro híbridos de milho cultivados com diferentes densidades de plantas

Modern maize hybrids have greater yield potential than cultivars used in the past, particularly under stressful conditions such as high plant population and water deficit. It is possible that the yield advantage presented by modern genotypes is partially due to their better ability to resist major maize diseases. This experiment was carried out to evaluate the incidence and severity of maize leaf, stem, and ear diseases on hybrids usually grown in Southern Brazil, under different plant populations. A split plot design was used, with the main plots disposed in randomized complete blocks. Three plant populations, equivalent to 50,000, 75,000 and 100,000pl ha-1, were tested in the main plot. The hybrids Ag 12, Ag 28, Ag 303 and Ag 9012, which were cultivated expressively in the 60s, 70s, 80s and 90s, respectively, were tested in the split plot. The enhancement in plant population promoted increases on the incidence of stem diseases caused by Fusarium moniliforme, Colletotrichum graminicola e Diplodia maydis, especially on Ag 12 and Ag 28, contributing to decrease their stem standability at harvesting. The hybrid Ag 9012 had lower incidence and severity of ear diseases caused by Fusarium moniliforme e Diplodia maydis, regardless of plant population. The hybrid Ag 9012 did not express lower severity levels of leaf diseases in relation to the older hybirds used in the trial.

Diversidade genética em acessos de feijão (Phaseolus vulgaris L.)

The correct characterization of genetic resources allows to identify sources of variability, a genetic profit during the plant breeding and use of these resources in the crop science. This research was aimed at evaluating genetic divergence in bean accessions of a germplasm of Santa Catarina, through interrelation among the agronomic character descriptor. Twenty bean (Phaseolus vulgaris L.) accessions were evaluated carried out in October 2005, using the randomized block design with three replications. The genotypes were studied using multivariable techniques to measure genetic divergence represented by the generalized distance of Mahalanobis. On the basis of the genetic similarity matrix, it was generated average distance grouping. Among 12 variable evaluated, the weight of 100 seeds had the higher contribution in the separation of the genotypes, followed for the pod width, pod length and yield of grains. The BAF 42, BAF 46, BAF 47 and BAF 57 accessions had the high productivity level and it must be better characterized to be incorporated in the programs of genetic breeding or use of these resources in the crop science.

Correlações canônicas: II - análise do rendimento de grãos de feijão e seus componentes

Thirty two bean genotypes (Phaseolus vulgaris L.) were evaluated in Lages/SC, Brazil, on the influence of seven characters of agronomic importance on the production of grains per unit of area. The experiment, in randomized blocks with four repetitions, was driven in the off season period in the agricultural year of 1995/96. This work aimed to estimate the intensity the association between the primary and secondary components of grain yield. The first group of variables (primary) was constituted by the number of grains per pod, number of pods per plant and the weight of a thousand grains. The second group (secondary) consisted of number of days from emergency to flowering, number of days from emergency to harvesting point, plant stature and the first pod insertion point. For the analysis of canonical correlations, the importance of secondary agronomic characters was evident in the traits number of pods per plant and grains per pod and also the influence of both on the final grain yield. Therefore, the coefficients of canonical correlations indicate that, in programs bean genetic improvement programs, to increase the production of grains one should select plants with larger number of pods per plant in order to obtain plants with higher stature and longer cycle.

Análise de trilha dos componentes do rendimento de grãos em genótipos de canola

Grain yield is a variable of complex association which has an economic importance. A trial was conducted in Lages, SC, during the 1996-growing season, in order to determine the association and the direct and indirect effects of some agronomic traits on grain yield of 12 canola genotypes, through the study of the phenotypic correlation and path analysis. A randomized complete block design with four replications per treatment was used. According to the analyses performed on the trial, plant height didn’t show any association with weight of 1,000 grains and grain yield. Path analysis showed that the primary components plant population per area and number of grains per plant have the largest direct impact on grain yield. On the other hand, the number of grains produced per plant is the major responsible for the increase in the weight of 1,000 grains. Path analysis also evidenced that the secondary component number of grains per pod has the highest direct effect on grain yield.

Genetic gain in agronomic traits of common bean in the region of Planalto Catarinense

The purpose of this study was to predict the genetic progress in the selection for common bean agronomic traits based on the trait expression, using two indices of adaptive selection. The existence of correlation between various traits in common bean breeding is a major restriction, but some tools that allow breeders to predict the expected gains could optimize results. The following traits were evaluated: (1) plant cycle (days), (2) plant height (in cm), (3) stem diameter (cm), (4) insertion of the first pod (cm); (5) number of pods per plant; (6) number of grains per pod; (7) pod length (cm). Results show the possibility of selecting accessions for several agronomically important traits evaluated together. The only genotype selected by both indices was UDESC 03, confirming the possibility of selecting plants with superior agronomic traits among genotypes of common bean landraces.

Reflexos da interação genótipo X ambiente e suas implicações nos ganhos de seleção em genótipos de feijão (Phaseolus vulgaris L.)

The importance of grains of legume plants for human feeding, specially black beans (Phaseolus vulgaris L.), has stimulated the breeders to select genotypes with high grains yield potential and wide adaptability to different conditions of cultivation in southern Brazil. The present work aimed at evaluating the reflexes of the genotype x environment interaction and its implications in the genetic gains of different selection approaches. The results revealed that the component of the interaction between genotype and environment overestimates the prediction of genetic parameters such as genetic variance and heritability. Differences among these estimates were observed apparently due to a high percentage of the complex part of the interaction. Besides, the genetic gains obtained with the direct selection were always superior to the indirect response. Comparatively, the pair of environments 1x3 revealed correlated response inferior and of opposite sign to the other estimates for the other pairs of environments studied. The first environment was the one which accumulated the higher interaction genotype by environment. It can be concluded that the interaction component has great relevance in the estimates of genetic gains, evidencing that this influence should be considered in the selection and in the recommendation of specific genotypes of bean breeding programs.