Renzo Garcia Von Pinho

Ruminal degradability of hard or soft texture corn grain at three maturity stages

The predominance of vitreous endosperm in hard texture flint corn (Zea mays L.) can decrease ruminal starch digestion comparatively to the farinaceous endosperm of dent corn, reducing energy content of the grain. The objective of this experiment was to evaluate the effects of texture and maturity stage on ruminal degradability of corn grain. Two dent and two flint hybrids were harvested at the early dent, half milk line, and black layer stages. The proportion of vitreous endosperm (vitreousness) in dent hybrids was 44.3%, while in flint it was 67.0%. There was a linear increase in vitreousness with advancing maturity. Flint hybrids at the early dent stage were more vitreous than dent at the black layer stage. The increase in vitreousness per maturation day was greater for flint hybrids. Grains were incubated in situ in the rumen of 6 cows. The 24-hour ruminal dry matter degradation was 63.3% for dent corn and 52.4% for flint corn. The 72-hour incubation residues of dent and flint hybrids were 7.6% and 15.6%, respectively. Ruminal degradability was similar between hybrids at the early dent and half milk line stages. There was a marked texture effect on ruminal degradability at the black layer stage (quadratic effect of maturity stage and interaction between texture and maturity stage). Use of dent hybrids, compared to flint hybrids, may result in smaller relative reduction in ruminal starch digestion in situations of late grain harvesting.

Inoculação de sementes de milho utilizando o Trichoderma harzianum como promotor de crescimento

Conduziu-se este trabalho com o objetivo de estudar o efeito do fungo Trichoderma harzianum como promotor de crescimento de sementes de milho tratadas com diferentes fungicidas. O experimento foi realizado em vasos em casa-de-vegetacao, adotando o delineamento experimental inteiramente casualizado em esquema fatorial (3x2), utilizando os tratamentos com fungicidas: Captan®, Maxim® e testemunha e inoculacao (com e sem inoculo) em quatro repeticoes. As caracteristicas agronomicas avaliadas foram: altura de planta, peso da materia seca da parte aerea e de raizes e tambem a tecnica de isolamento do fungo nas raizes aos 45 dias apos semeadura. Observou-se diferenca significativa somente para o fator inoculo na caracteristica peso de materia seca de raizes. Pelos resultados obtidos, verificou-se que o fungo Trichoderma harzianum estimulou maior acumulo de materia seca nas raizes das plantas de milho e tambem estava presente nas raizes das plantas oriundas de sementes inoculadas, independentemente do tratamento fungicida das sementes.

Avaliação de características agronômicas e de produção de forragem e grãos de milho em diferentes densidades de semeadura e espaçamentos entre linhas

O milho Zea mays L. e muito utilizado para a producao de forragem e graos em todo o mundo, devido ao seu grande potencial produtivo e adaptabilidade aos mais diferentes ambientes. Aspectos relacionados ao arranjo de plantas na area, como a densidade, o espacamento e a arquitetura da cultivar, podem ser determinantes na producao de forragem e graos. A reducao do espacamento e o aumento da densidade podem aumentar a produtividade e a eficiencia operacional na cultura do milho. Visou-se com este trabalho, estudar o comportamento de hibridos de milho de diferentes arquiteturas foliares, submetidos a dois espacamentos entre linhas e a duas densidades de plantas, em dois anos agricolas. Em cada ano, foram conduzidos dois experimentos, sendo que no primeiro adotou-se o espacamento de 0,70 m e no segundo experimento 0,90 m entre linhas. O delineamento utilizado foi o de blocos casualizados em esquema de fatorial 3 x 2, para avaliar os desempenhos de tres hibridos (AG1051, AG 9010, DKB440) sob duas densidades de plantas (55.000 e 75.000 plantas ha-1). A reducao do espacamento entre linhas de 0,90 m para 0,70 m proporciona maiores producoes de meteria seca (MS) e de graos de milho, independentemente do ano de plantio e da densidade de plantas. O aumento da densidade de plantas de 55.000 plantas ha-1 para 75.000 plantas ha-1 proporciona aumento na producao de MS e na producao de graos de milho, independente do ano de plantio e do espacamento entre linhas. A cultivar AG1051 apresenta as maiores producoes de MS e as maiores alturas de plantas e de espigas, independentemente do ano de plantio e do espacamento adotado. As cultivares AG9010 e DKB440 destacaram-se em relacao a produtividade de graos.

Influência do potássio e da calagem na composição química, qualidade fisiológica e na atividade enzimática de sementes de soja

A composicao quimica das sementes pode ser influenciada por fatores geneticos, ambientais e pela disponibilidade de nutrientes no solo durante a producao e, como consequencia, terem o seu vigor afetado. O potassio pode influenciar a atividade de varias enzimas presentes nas plantas, necessarias em varias reacoes envolvidas na utilizacao de energia, sintese de amido, metabolismo do nitrogenio e respiracao. Avaliou-se o efeito da adubacao potassica e da calagem na composicao quimica, qualidade fisiologica e na atividade de enzimas de sementes de soja. A pesquisa foi desenvolvida nos laboratorios de analises e biotecnologia de sementes do Departamento de Agricultura e no Laboratorio de Producao Vegetal do Departamento de Ciencias dos Alimentos da Universidade Federal de Lavras (UFLA). Em sementes de soja do cultivar Msoy 8001, produzidas sob 2 niveis de saturacao por base (48% e 85%) e quatro doses de K2O por hectare (0, 50, 100 e 200 kg), foram avaliados teores de oleo e proteina, germinacao, envelhecimento acelerado e atividade das enzimas envolvidas nos processos de germinacao e deterioracao de sementes. A adubacao potassica nao afeta a germinacao e o vigor das sementes, enquanto a elevacao da saturacao por base, proporciona maior vigor de sementes de soja. Ha aumento no teor de oleo e reducao no teor de proteina em sementes de soja a medida que a dose de K2O e aumentada. Ocorre aumento de teor de proteinas em sementes de soja, produzidas sob maiores niveis de saturacao por base. A atividade das enzimas piruvato quinase, esterase e alcool desidrogenase em sementes de soja e afetada pela concentracao de potassio e saturacao por base no solo.

Produtividade e qualidade da silagem de milho e sorgo em função da época de semeadura

With the objective to evaluate the influence of different times of sowing in the productivity and silage quality of corn and sorghum cultivars and also of verifying the possibility of substitution of corn to sorghum to silage production, experiments were installed considering three times of sowing in area of the Department of Agriculture of the Federal University, during the agricultural year of 2002/2003. Three groups had been evaluated to cultivars (three of double purpose sorghum, three of forage sorghum and three of corn) at three times of sowing (19/11/2002, 19/12/2002, and 18/1/2003). The experimental design was of blocks randomized in factorial scheme 3 groups to cultivars (to cultivars) x 3 times of sowing (times), with four repetitions. Productivity of dry matter was evaluated (MS), participation of panicle or spike in the MS, and the rude protein percentages, fiber in neutral detergent, fiber in acid detergent and lignin. Significant effect was observed to cultivars, times of sowing to all characteristics evaluated. The presence of interaction cultivars*times was verified for the productivity of dry matter, participation of panicle or spike in the MS and the rude protein percentages. Independently of times of sowing, with the corn present silage with smaller fiber tenor than with any sorghum types, and productivity of dry matter similar to the one of forage sorghum and superior to the one of sorghum of double intention. The largest production of dry matter of corn and sorghum was obtained when the sowing is made in November. Corn and sorghum silage of larger nutritional value was obtained when the sowing was made in January. Under the production point of view and of quality nutritional of the forage, it is not viable the substitution of the corn for sorghum.

Efeito da cercosporiose no rendimento de híbridos comerciais de milho

Effect of Gray leaf spot on yield of Commercial Maize Hybrids With the objective of quantifying the effect of gray leaf spot (Cercospora zeae-maydis) on yield of 12 commercial maize hybrids and of correlating grain yield reduction with disease severity, two experiments were performed at two sowing dates (November 11 th and December 23 rd , 2005) in the experimental area of the Federal University of Lavras (UFLA), Lavras, MG, Brazil. Disease control in healthy plots of all hybrids was obtained through two applications of epoxiconazol + pyraclostrobin – 37.5 + 99.75 g i.a.ha -1 ) at a 15-day interval. In uncontrolled plots, epidemic development started from natural inoculum present in the area. Eight evaluations of disease severity based on visual symptoms were performed at seven-day intervals from the 60 th day after maize emergence, ranging from 1 (resistant) to 9 (susceptible). The area under the disease progress curve (AUDPC) was estimated and grain yield per plot was also obtained. Results of damage percentage and correlations between grain yield and damage percentage with the estimates of the AUDPC were supported by the data. Damage intensity varied according to sowing season and hybrid, with an average of 13.3%. Maize gray leaf spot reduces the corn grain yield, mainly in the late sowing season, and the use of resistant hybrids excludes the chemical control of the disease. Additional keywords: Zea mays, damage, disease evaluation, fungal disease.

Adubação nitrogenada, densidade de semeadura e espaçamento entre fileiras na cultura do milho em sistema plantio direto

Among the practices and techniques employed for obtaining increased corn yield, the choice of plant arrangement and time of nitrogen topdressing are among the most important, associated with the choice of the hybrid and cropping system. The objective of this trial was study in no-tillage system, the influence of four times of application of nitrogen fertilization associated with three sowing rates and two interrow spacings for two corn cultivars in south Minas Gerais. On the site, two experiments in no-tillage system were established, the first one being set up with the spacing of 0.45 m and the second spacing of 0.90 m. In each experiment, two corn cultivars (P 30K75 and TORK), three sowing rates (55 thousand, 70 thousand and 85 thousand plants ha-1) and four times of application of nitrogen fertilization: 40 kg ha-1 of N applied on the occasion of sowing without any nitrogen topdressing; 40 kg ha-1 of N at sowing + 120 kg ha-1 of N topdressed soon after sowing; 40 kg ha-1 of N at sowing + 60 kg ha-1 of N topdressed at the stage of 4 to 5 leaves + 60 kg ha-1 of N topdressed at the stage of 7 to 8 leaves, 40 kg ha-1 of N at sowing + 120 kg ha-1 of N topdressed at the stage of 6 to 7 leaves. Nitrogen fertilization done into covering, in one or two applications influences in the height of the plants, the height of insertion of the ear and provides significant increases in corn grain yield.

Desempenho de híbridos experimentais e comerciais de milho para produção de milho verde

Conduziu-se este trabalho com objetivo de avaliar o desempenho de 32 hibridos experimentais e 4 hibridos comerciais para producao de milho verde em Lavras, MG. O delineamento utilizado foi de blocos ao acaso com duas repeticoes. Foram avaliadas sete caracteristicas de interesse agronomico e comercial para a producao de milho verde. Os dados obtidos foram submetidos a analise de variância, decompondo o efeito dos hibridos em hibridos comerciais, hibridos experimentais e hibridos comerciais versus hibridos experimentais. Foram feitos ainda estudos de correlacao entre as diferentes caracteristicas agronomicas dos hibridos. Entre os hibridos avaliados ha hibridos experimentais promissores com desempenho superior a hibridos comerciais amplamente utilizados no Brasil. Considerando as caracteristicas avaliadas, os hibridos AG 1051, AG 4051, GNS 03, GNS 21, GNS 23 e GNS 35 foram os mais promissores. E possivel reduzir o numero de caracteristicas avaliadas em experimentos com milho verde, uma vez que existem associacoes entre as principais caracteristicas avaliadas para essa finalidade. A produtividade de espigas empalhadas e despalhadas e a cor dos graos sao caracteristicas imprescindiveis nessa avaliacao.

Evaluation of maize hybrids and environmental stratification by the methods AMMI and GGE biplot

The purpose of this study was to evaluate yield stability, adaptability and environmental stratification by the methods AMMI (Additive Main Effects and Multiplicative Interaction Analysis) and GGE (Genotype and Genotypes by Environment Interaction) biplot and to compare the efficiency of these methods. Data from the evaluation of 20 experimental single-cross and three commercial hybrids and 11 locations, in two growing seasons, 2005/2006 and 2006/2007 were used. Analyses of variance, adaptability, stability and environmental stratification were performed. A better combination of adaptability and stability was observed in the hybrids 10 and 16, according to the graphics of AMMI and GGE biplot methods, respectively. The number of locations could be reduced by 28% based on stratification. The predictive correlation of the AMMI and GGE methods was 0.88 and 0.86, respectively. The results showed that it is possible to reduce the number of evaluation sites; AMMI tended to be more accurate than GGE analysis.

Genetic purity certificate in seeds of hybrid maize using molecular markers

One of the main features that confer high quality to the seed is its genetic purity, in which one of the major causes of contamination is the self-pollination of the female parent. Up to date, there is no accurate and fast methods for detecting such contamination. Thus, this work was carried out to certify the genetic purity in seeds of hybrid maize using different biochemical and DNA-based markers. Two single-cross hybrids and their parental lines derived from the maize breeding program at UFLA were evaluated by isoenzymatic pattern of alcohol dehydrogenase (ADH), esterase (EST), acid phosphatase (ACP), glutamate-oxaloacetate transaminase (GOT), malate dehydrogenase (MDH), isocitrate dehydrogenase (IDH), phosphoglucomutase (PGM), 6-phosphoglucomate dehydrogenase (PGDH), catalase (CAT) and s-glucosidade (sGLU) and by microsatellites markers. The enzymatic systems that were able to distinguish the hybrids from their parental line were the catalase, the isocitrate dehydrogenase and the esterase. The esterase showed a Mendelian segregation pattern for UFLA 8/3 hybrid, that enables a safer genetic purity certificate. Microsatellites were able to differentiate the hybrid lines and the respective parental lines. Moreover, this technique was fast, precise and without environment effects. For microsatellites, the amplification pattern was identical when young leaves or seeds were used as DNA source. The possibility of using seeds as DNA source would accelerate and facilitate the role process of the genetic purity analysis.