No description available.

No description available.

The yield of short-season hybrids is lower than long-season hybrids, mainly as a result of the low final leaf area developed by the short-season plants. This is due to the smaller plant stature and smaller leaf number and size of short-season adapted hybrids. In addition, in short-season areas the thermal-time available may be insufficient to mature grain of current maize hybrids. Maize hybrids which accumulate leaf area quickly, mature earlier, yield well and tolerate higher population densities better than the currently available hybrids would be more suitable for production in short-season areas. The "Leafy reduced-stature" maize hybrids, which have only recently been developed, have traits which address these criteria. There has been no previous effort to evaluate the effects of more than two plant population densities or the effects of planting patterns on the yield, yield components and vegetative growth of these hybrids. in 1995, field experiments were conducted at two sites near Montreal to compare the response of leafy reduced-stature (LRS), non-leafy normal stature (NLNS), and non-leafy reduced-stature (NLRS) maize hybrids to plant population densities and planting patterns. LRS maize hybrids showed the most rapid growth of the first ear, and the highest yield per single plant and per hectare at high plant population densities in paired rows. LRS hybrids also had longer grain filling periods, lower grain moisture contents and higher harvest indices than conventional (NLNS) hybrids. Rapid growth of the first ear and a higher harvest index are indications that LRS hybrids should be more tolerant of higher population densities than currently available hybrids. Therefore, LRS hybrids show promise for production in short-season areas at high plant population densities where maize cultivation is not currently economical due to shortness of the growing-season.

An experiment was carried out at Redland Bay on the south-eastern coast of Queensland from (16/2/1991 to 27/6/1991) in an attempt to relate the performance of maize (Zea mays L.)/cowpea (Vigna unguiculata (L) Walp.) intercrops to radiation interception and to radiation availability to cowpea and to ascertain the effects of cowpea morphological characteristics. A quick maturing maize cultivar (DK529) and two cowpea cultivars (Red Caloona and 672330) were used. Changes in light availability to cowpea in intercrops were made by varying maize density. Three plant population densities were used: 22,000 plants ha^-1, 44,000 plants ha^-1, and 67,000 plants ha^-1. Both cowpea cultivars were very vegetative and vigorous in growth with little difference in their morphological characteristics. Cowpea cultivar 1 (Red Caloona) was however a better climber and retained green leaves for a longer duration. Increasing maize plant population density effectively reduced the amount of light reaching the cowpea canopy. Light availability was reduced to a minimum of 13% and 15% in the high maize plant population density and to a minimum of 47% and 42% in the low maize plant population density in cowpea cultivar 1 and 2 respectively. Intercropping reduced growth and yield of both cowpea cultivars through reductions in cowpea leaf area index (LAI), light interception and pod number. It also caused reductions in seed size in cowpea cultivar 2 (67233). Increasing maize plant population density further reduced all the above parameters. Maize growth and yield was affected by intercropping but to a lesser extent. Maize yields were reduced by 16% and 14% under cowpea cultivar 1 and cowpea cultivar 2 respectively, compared to an average reduction of 68% and 82% in cowpea cultivars 1 and 2 across the 3 maize plant population density. Radiation use efficiency (RUE) of the intercrops was lower than that of maize sole crop but higher than that of cowpea sole crop. Intercropping proved to be more advantageous in the vegetative stages of growth than in the reproductive stage except in the medium maize plant population density treatment. This was attributed to better light use efficiency in the early growth in intercrops than sole crops which was estimated to be between 1.1 and 2.9 time higher in intercrops than in sole maize in the first 20 days after sowing (DAMS) . Results indicated that LAI and leaf longevity had a large effect on radiation interception and use in cowpea. Cowpea cultivar 2 was better yielding in sole crop that cowpea cultivar 1 (954 Vs 621 Kgha^-1) but was more affected by intercrop (157 Vs Kgha^-1). An advantage of intercropping was only obtained in the medium maize plant population density intercrops. These were however small advantages (13% and 11%) in cowpea cultivar 2 and cultivar 1 respectively. Intercropping maize with these two cowpea cultivars would therefore be of advantage only, where the interest of the farmer is in the production of maize grain and cowpea leaf, wither for consumption, livestock feed or as green manure.

An experiment was carried out at Redland Bay on the south-eastern coast of Queensland from (16/2/1991 to 27/6/1991) in an attempt to relate the performance of maize (Zea mays L.)/cowpea (Vigna unguiculata (L) Walp.) intercrops to radiation interception and to radiation availability to cowpea and to ascertain the effects of cowpea morphological characteristics. A quick maturing maize cultivar (DK529) and two cowpea cultivars (Red Caloona and 672330) were used. Changes in light availability to cowpea in intercrops were made by varying maize density. Three plant population densities were used: 22,000 plants ha^-1, 44,000 plants ha^-1, and 67,000 plants ha^-1. Both cowpea cultivars were very vegetative and vigorous in growth with little difference in their morphological characteristics. Cowpea cultivar 1 (Red Caloona) was however a better climber and retained green leaves for a longer duration. Increasing maize plant population density effectively reduced the amount of light reaching the cowpea canopy. Light availability was reduced to a minimum of 13% and 15% in the high maize plant population density and to a minimum of 47% and 42% in the low maize plant population density in cowpea cultivar 1 and 2 respectively. Intercropping reduced growth and yield of both cowpea cultivars through reductions in cowpea leaf area index (LAI), light interception and pod number. It also caused reductions in seed size in cowpea cultivar 2 (67233). Increasing maize plant population density further reduced all the above parameters. Maize growth and yield was affected by intercropping but to a lesser extent. Maize yields were reduced by 16% and 14% under cowpea cultivar 1 and cowpea cultivar 2 respectively, compared to an average reduction of 68% and 82% in cowpea cultivars 1 and 2 across the 3 maize plant population density. Radiation use efficiency (RUE) of the intercrops was lower than that of maize sole crop but higher than that of cowpea sole crop. Intercropping proved to be more advantageous in the vegetative stages of growth than in the reproductive stage except in the medium maize plant population density treatment. This was attributed to better light use efficiency in the early growth in intercrops than sole crops which was estimated to be between 1.1 and 2.9 time higher in intercrops than in sole maize in the first 20 days after sowing (DAMS) . Results indicated that LAI and leaf longevity had a large effect on radiation interception and use in cowpea. Cowpea cultivar 2 was better yielding in sole crop that cowpea cultivar 1 (954 Vs 621 Kgha^-1) but was more affected by intercrop (157 Vs Kgha^-1). An advantage of intercropping was only obtained in the medium maize plant population density intercrops. These were however small advantages (13% and 11%) in cowpea cultivar 2 and cultivar 1 respectively. Intercropping maize with these two cowpea cultivars would therefore be of advantage only, where the interest of the farmer is in the production of maize grain and cowpea leaf, wither for consumption, livestock feed or as green manure.

No description available.

Call number: LD2668 .T4 1986 M87 / Master of Science / Agronomy

A investigação da mancha ocular do milho foi baseada no seu agente causal e na elaboração de uma escala diagramática da doença que auxiliou na avaliação da sensibilidade dos genótipos de milho, correlacionada com a resposta de defesas bioquímicas da planta. Na primeira etapa do trabalho, 35 isolados de Kabatiella zeae, de diferentes materiais genéticos de milho, foram avaliados quanto à coloração e aspecto das colônias e mensuração dos esporos do fungo em BSA. Os meios de cultura utilizados foram BSA (batata, sacarose e ágar), MA (malte e ágar), AvA (aveia e ágar) e FA (fubá de milho e ágar). Discos de 5 mm de diâmetro, foram colocadas no centro das placas contendo os respectivos meios de cultura. As placas foram incubadas a 24° C com fotoperíodo de 12 horas , por 10 dias. As características das colônias e mensuração dos conídios foram avaliadas em BSA, e o crescimento radial, nos quatro meios. Houve diferença entre todos os isolados em relação aos meios de cultura. Observou-se que a dimensão dos esporos variou de 3- 4 x 27-33 μm, de largura e comprimento, respectivamente, e que 80% dos isolados apresentaram coloração clara (rosa) e aspecto coreáceo e enrugado, e o maior crescimento micelial foi observado no meio BSA. A escala diagramática foi desenvolvida coletando-se 110 folhas doentes, aleatoriamente no campo, eliminando-se 20 cm da extremidade, sendo utilizados os 20 cm seguintes. Foi mensurada a área foliar e área das lesões para determinação dos limites de severidade mínima e máxima da doença, e os níveis intermediários calculados matematicamente. Os níveis de severidade observados em campo seguiram incrementos logarítmicos, representando: 0,9; 2,0; 4,0; 9,0; 18,0; 32,0 e 51,0% da área foliar lesionada. A validação da escala consistiu-se em duas etapas: na primeira, 10 avaliadores, com experiência na avaliação de doenças em plantas, avaliaram 30 folhas com diferentes níveis de severidade, com e sem o uso da escala diagramática. Na segunda etapa, outros 10 avaliadores, sem experiência, fizeram as mesmas avaliações, com e sem uso da escala diagramática. Por meio de regressão linear, foram confrontados valores de severidade reais e estimados, sendo analisadas a acurácia e a precisão dos avaliadores. Constatou-se melhora na acurácia e na precisão das estimativas visuais efetuadas com o auxílio da escala diagramática. A reação de genótipos de milho à mancha ocular foi avaliada no município de Pato Branco-PR na safra 2006/2007, com 33 híbridos e na safra 2007/2008, com 10 híbridos em duas épocas de semeadura e no município de Palma Sola-SC, na safra 2007/2008 com 8 híbridos. Os híbridos AG 9020 e SPRINT apresentaram maior suscetibilidade à doença, em relação à AS 1565 e DKB 234, repetindo este comportamento nos dois locais e épocas de cultivo. A enzima peroxidase foi observada em maior concentração nas folhas dos híbridos de milho com menor severidade de mancha ocular. / This investigation on corn eyespot was based on its causal agent and on the preparation of a diagrammatic scale that helped evaluate the reaction of corn genotypes, in correlation with the response obtained from the plant’s biochemical defenses. In the first step of the study, 35 Kabatiella zeae isolates from different corn genetic materials had their colonies evaluated for color and aspect, and their spores measured in PSA medium. The following culture media were used: PSA (potato, sucrose, agar), MA (malt and agar), OA (oat and agar) and CA (corn flour and agar). Disks (5 mm in diameter) were placed in the center of Petri dishes containing the respective culture media. The dishes were incubated at 24°C and a 12-hour photoperiod for 10 days. Colony traits and conidia measurements were evaluated in PSA, while radial growth was evaluated in the four media. There were differences between all isolates with regard to the culture media. Spore size varied from 3-4 × 27-33 μm in width and length, respectively, and 80% of the isolates had a light color (pink) and a coriaceous and wrinkled aspect; the highest mycelial growth was observed in the PSA medium. A diagrammatic scale was developed by randomly collecting 110 diseased leaves in the field, discarding 20 cm from the leaf tip, and using the next 20 cm. Measurements were made for leaf area and the area containing lesions in order to determine minimum and maximum severity limits of the disease; intermediate levels were calculated mathematically. The severity levels observed in the field followed logarithmic increases, representing: 0.9; 2.0; 4.0; 9.0; 18.0; 32.0; and 51.0% of leaf area with lesions. Scale validation consisted of two steps: in the first, 10 evaluators experienced in plant disease evaluations assessed 30 leaves with different severity levels, both using and not using the diagrammatic scale. In the second step, another 10 naive (without experience) evaluators performed the same evaluations, both using and not using the diagrammatic scale. Actual and estimated severity values were compared by linear regression, and evaluator accuracy and precision were analyzed. Better accuracy and precision were obtained for visual estimates made with the diagrammatic scale. The reaction of corn genotypes to eyespot was evaluated in the city of Pato Branco-PR during the 2006/2007 growing season using 33 hybrids, and during the 2007/2008 growing season using 10 hybrids at two distinct sowing seasons, and in the city of Palma Sola-SC during the 2007/2008 growing season with 8 hybrids. Hybrids AG 9020 and SPRINT were the most susceptible to the disease in relation to AS 1565 and DKB 234; this behavior was observed in both years and planting seasons. The peroxidase enzyme was observed at higher concentrations in leaves of corn hybrids with the lowest eyespot severity.

CAPES / Nos últimos anos o milho (Zea mays) tem recebido grande valorização por parte dos produtores agrícolas passando de uma mera cultura destinada para o programa de rotação de culturas, para uma commodity agrícola. Entre os principais fatores que vem influenciando o aumento da área plantada, bem como o crescimento da cultura são a utilização de materiais mais produtivos, arranjo de plantas mais adequadas ao cultivar utilizado, redução do espaçamento entre linhas e/ou aumento da densidade populacional. Neste contexto, esse trabalho tem por objetivo avaliar o desenvolvimento e produtividade da cultura do milho sob densidades de plantas e espaçamentos entre linhas simples e duplas. O experimento foi realizado no Município de São João, PR em propriedade particular. O delineamento utilizado foi o de blocos casualizados, com quatro repetições em esquema bifatorial 5 x 5, sendo cinco espaçamentos entre linhas (linhas duplas: 0,4 x 0,2; 0,5 x 0,2; 0,6 x, 0,2; 0,7 x 0,2 m e espaçamento simples entre linhas como testemunha: 0,7 m) e cinco densidades de plantio (50.000; 65.000; 80.000; 95.000; 110.000 plantas ha-1). As unidades experimentais foram constituídas de quatro linhas de 5 metros de comprimento, sendo a área útil composta pelas duas linhas centrais por 3 metros de comprimento. No estádio V12 foram avaliados os caracteres altura de plantas e diâmetro de colmo. No estádio R5 foram avaliadas a altura de plantas, diâmetro de colmo, altura de inserção da primeira espiga, índice de espigas e população final de plantas. Os componentes de rendimento avaliados foram o comprimento de espiga, número de fileiras de grãos por espiga, massa de 1000 grãos e produtividade. A colheita do milho foi realizada manualmente, sendo os grãos processados por trilhadora estacionária. Os dados de produtividade tiveram índices corrigidos a 13% de umidade. Os dados obtidos foram tabulados e submetidos às análises de variância para avaliação dos efeitos dos fatores espaçamentos entre linhas e densidades de plantas e sua interação utilizando o software Genes. Para avaliar os efeitos dos espaçamentos linhas duplas e o contraste entre linhas duplas e testemunha (linha simples), as médias foram comparadas pelo teste “T” a 5% de probabilidade. Quando a interação entre os espaçamentos linhas dupla e população de plantas foi significativa, os dados foram submetidos à análise em superfície de resposta. O aumento da densidade populacional provocou diminuição no diâmetro de colmo, no índice de espigas, número de fileiras por espigas, comprimento de espiga e produtividade. O espaçamento entre linhas influenciou significativamente a altura de plantas, altura de inserção da primeira espiga e produtividade, onde os maiores resultados obtidos no espaçamento simples. Independente da população de plantas utilizada, o índice de espigas e diâmetro do colmo foram maiores no espaçamento linha dupla. A produtividade de grãos respondeu de forma linear negativa para o aumento da densidade de plantas, indicando que o híbrido SUPERIS possui baixa adaptabilidade para altas populações. / In the last years, maize (Zea mays) has received great valuation by the farmers from a mere culture intended for the program of crop rotation, to an agricultural commodity. Among the main factors that have been influencing the increase of planted area and crop progress are the use of most productive materials, better plant arrangement from the used cultivar, reduction of space between lines and / or increasing population density. In this context, this study aims to assess the development and productivity of maize under plant densities and spacings between single and double lines. The experiment was conducted in the city of São João, PR on private property. The experimental design was a randomized complete block design with four replications in bifactorial scheme 5 x 5, consisting in five row widths (double rows: 0,4 x 0,2; 0,5 x 0,2; 0,6 x, 0,2; 0,7 x 0,2 m and single row width to be the control: 0,7 m) and five plant densities (50.000; 65.000; 80.000; 95.000; 110.000 plants ha-1).The experimental units were composed of four rows of 5 meters length, with the usable area composed of the two central rows by 3 meters long. At V12 stage the characters plant height and stem diameter were evaluated. At R5 stage were evaluated height of plants, stem diameter, insertion height of first ear, ears index and final plants population. The yield components evaluated were ear length, number of seed rows per ear, 1000 seeds weight and yield. The harvest was made manually, the seeds were processed by a stationary threshing. Productivity data were corrected with index to 13% of moisture. Data were tabulated and submitted to analysis of variance to assess the effects of the factors row widths and plant densities and their interaction using the Genes software. To evaluate the effects of double row spacings and the contrast between double rows and the control (Single Row), the means were compared by “T” test at 5% probability. When the interaction between the double row spacings and plant population was significant, the data were analyzed on the surface response. The increase in population density promoted reduction in stem diameter, the ears index, number of rows per ear, ear length and productivity. The space between lines significantly influenced the plant height, insertion height of first ear and productivity, where higher results were found in single spacing. Independent of plant population used the spike index and stem diameter were higher in double line spacing. Grain yield responded negatively linearly to the increase of density, indicating that the hybrid SUPERIS has poor adaptability to high populations.

A investigação da mancha ocular do milho foi baseada no seu agente causal e na elaboração de uma escala diagramática da doença que auxiliou na avaliação da sensibilidade dos genótipos de milho, correlacionada com a resposta de defesas bioquímicas da planta. Na primeira etapa do trabalho, 35 isolados de Kabatiella zeae, de diferentes materiais genéticos de milho, foram avaliados quanto à coloração e aspecto das colônias e mensuração dos esporos do fungo em BSA. Os meios de cultura utilizados foram BSA (batata, sacarose e ágar), MA (malte e ágar), AvA (aveia e ágar) e FA (fubá de milho e ágar). Discos de 5 mm de diâmetro, foram colocadas no centro das placas contendo os respectivos meios de cultura. As placas foram incubadas a 24° C com fotoperíodo de 12 horas , por 10 dias. As características das colônias e mensuração dos conídios foram avaliadas em BSA, e o crescimento radial, nos quatro meios. Houve diferença entre todos os isolados em relação aos meios de cultura. Observou-se que a dimensão dos esporos variou de 3- 4 x 27-33 μm, de largura e comprimento, respectivamente, e que 80% dos isolados apresentaram coloração clara (rosa) e aspecto coreáceo e enrugado, e o maior crescimento micelial foi observado no meio BSA. A escala diagramática foi desenvolvida coletando-se 110 folhas doentes, aleatoriamente no campo, eliminando-se 20 cm da extremidade, sendo utilizados os 20 cm seguintes. Foi mensurada a área foliar e área das lesões para determinação dos limites de severidade mínima e máxima da doença, e os níveis intermediários calculados matematicamente. Os níveis de severidade observados em campo seguiram incrementos logarítmicos, representando: 0,9; 2,0; 4,0; 9,0; 18,0; 32,0 e 51,0% da área foliar lesionada. A validação da escala consistiu-se em duas etapas: na primeira, 10 avaliadores, com experiência na avaliação de doenças em plantas, avaliaram 30 folhas com diferentes níveis de severidade, com e sem o uso da escala diagramática. Na segunda etapa, outros 10 avaliadores, sem experiência, fizeram as mesmas avaliações, com e sem uso da escala diagramática. Por meio de regressão linear, foram confrontados valores de severidade reais e estimados, sendo analisadas a acurácia e a precisão dos avaliadores. Constatou-se melhora na acurácia e na precisão das estimativas visuais efetuadas com o auxílio da escala diagramática. A reação de genótipos de milho à mancha ocular foi avaliada no município de Pato Branco-PR na safra 2006/2007, com 33 híbridos e na safra 2007/2008, com 10 híbridos em duas épocas de semeadura e no município de Palma Sola-SC, na safra 2007/2008 com 8 híbridos. Os híbridos AG 9020 e SPRINT apresentaram maior suscetibilidade à doença, em relação à AS 1565 e DKB 234, repetindo este comportamento nos dois locais e épocas de cultivo. A enzima peroxidase foi observada em maior concentração nas folhas dos híbridos de milho com menor severidade de mancha ocular. / This investigation on corn eyespot was based on its causal agent and on the preparation of a diagrammatic scale that helped evaluate the reaction of corn genotypes, in correlation with the response obtained from the plant’s biochemical defenses. In the first step of the study, 35 Kabatiella zeae isolates from different corn genetic materials had their colonies evaluated for color and aspect, and their spores measured in PSA medium. The following culture media were used: PSA (potato, sucrose, agar), MA (malt and agar), OA (oat and agar) and CA (corn flour and agar). Disks (5 mm in diameter) were placed in the center of Petri dishes containing the respective culture media. The dishes were incubated at 24°C and a 12-hour photoperiod for 10 days. Colony traits and conidia measurements were evaluated in PSA, while radial growth was evaluated in the four media. There were differences between all isolates with regard to the culture media. Spore size varied from 3-4 × 27-33 μm in width and length, respectively, and 80% of the isolates had a light color (pink) and a coriaceous and wrinkled aspect; the highest mycelial growth was observed in the PSA medium. A diagrammatic scale was developed by randomly collecting 110 diseased leaves in the field, discarding 20 cm from the leaf tip, and using the next 20 cm. Measurements were made for leaf area and the area containing lesions in order to determine minimum and maximum severity limits of the disease; intermediate levels were calculated mathematically. The severity levels observed in the field followed logarithmic increases, representing: 0.9; 2.0; 4.0; 9.0; 18.0; 32.0; and 51.0% of leaf area with lesions. Scale validation consisted of two steps: in the first, 10 evaluators experienced in plant disease evaluations assessed 30 leaves with different severity levels, both using and not using the diagrammatic scale. In the second step, another 10 naive (without experience) evaluators performed the same evaluations, both using and not using the diagrammatic scale. Actual and estimated severity values were compared by linear regression, and evaluator accuracy and precision were analyzed. Better accuracy and precision were obtained for visual estimates made with the diagrammatic scale. The reaction of corn genotypes to eyespot was evaluated in the city of Pato Branco-PR during the 2006/2007 growing season using 33 hybrids, and during the 2007/2008 growing season using 10 hybrids at two distinct sowing seasons, and in the city of Palma Sola-SC during the 2007/2008 growing season with 8 hybrids. Hybrids AG 9020 and SPRINT were the most susceptible to the disease in relation to AS 1565 and DKB 234; this behavior was observed in both years and planting seasons. The peroxidase enzyme was observed at higher concentrations in leaves of corn hybrids with the lowest eyespot severity.