-Diallel analyses are commonly used for the estimate of population genetic effects. Different models can be used, with a direct effect on the inferences. The objective of this study was to determine and compare two diallel analysis models, fixed and random, regarding the combining effects among six wheat genotypes. The experiment was conducted in the county of Capão do Leão/RS in the year 2006. Six wheat genotypes were used that were used for artificial crosses according to a complete diallel model without reciprocals, resulting in 15 hybrid combinations. The data were subjected to diallel analyses according to model 2 of Griffing (fixed) and BLUP (random). The results show that both diallel models indicate similar general combining ability effects.On the other hand, for the specific combining ability, the data must be used with caution, considering the two models simultaneously.

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The present work aimed at evaluating the canonical correlations between traits of grain yield and morphological traits in maize, in order to verify the associations and interdependence among groups. The experiment was conducted in the agricultural year 2010/2011; consisted of 25 corn hybrids, allocated in five locations of the states of Paraná, Santa Catarina e Rio Grande do Sul. Settled two groups of traits, with Group I comprised agronomic characters of grain yield: grain yield plot, the total weight of grains and weight of hundred grains and the group II formed by morphology: stem diameter , leaf angle , tassel length , number of tassel branches , total leaf area , insertion of the ear , plant height in maize. The first, second and third canonical pair proved significant at the 1% level of probability, using the chi-square test, indicating that the groups are not independent. Hybrids with higher plant height, insertion of ear and leaf angle and fewer branches and tassel length are associated with the increase in weight of hundred grains in maize. To increase the grain weight, should be considered hybrids with greater insertion of the ear, leaf area and shorter length of the tassel. The increase in leaf area, as well as smaller tassel length is related positively to increase grain yield in maize.Additional keywords: associations between characters; multivariate analysis; Zea mays L. ResumoO presente trabalho objetivou avaliar as correlações canônicas entre caracteres que compõem o rendimento de grãos e caracteres morfológicos em milho, visando a verificar as associações e a interdependência entre os grupos. O experimento foi conduzido no ano agrícola de 2010/2011, compreendido por 25 híbridos simples de milho, alocados em cinco locais dos Estados do Paraná, Santa Catarina e Rio Grande do Sul, Brasil. Estabeleceram-se dois grupos de caracteres, sendo o grupo I formado por caracteres agronômicos que compõem o rendimento de grãos: rendimento de grãos da parcela (RG), massa total de grãos da espiga (MG) e massa de cem grãos (MCG), e o grupo II formado por caracteres morfológicos: diâmetro do colmo (DC), ângulo de folha (AF), comprimento do pendão (CP), número de ramificações do pendão (NR), área foliar total (AFT), altura da inserção da espiga (AE) e altura de planta (AP) em milho. O primeiro, o segundo e o terceiro pares canônicos revelaram-se significativos a nível de 1% de probabilidade, pelo teste qui-quadrado, indicando que os grupos não são independentes. Híbridos com maiores altura de plantas, de inserção de espiga e ângulo foliar e menor número de ramificações e comprimento do pendão estão associados com o incremento da massa de cem grãos em milho. Para incremento de massa de grãos, devem ser considerados híbridos com maior altura da inserção da espiga, área foliar e menor comprimento do pendão. O aumento da área foliar, assim como menor comprimento do pendão, está relacionado favoravelmente para o aumento do rendimento de grãos em milho.Palavras-chave adicionais: análise multivariada; associações ...

RESUMOA resposta da soja à adubação fosfatada em solos com teores abaixo do nível crítico é inversamente proporcional ao teor de fósforo do solo, que esteja disponível para as plantas. Assim, este trabalho teve por objetivo avaliar algumas características agronômicas e o rendimento de grãos de cultivares de soja, cultivadas em solo com baixo teor de fósforo, e submetidas a diferentes níveis de adubação fosfatada. Foi instalado um experimento em Rolim de Moura -RO, em um Latossolo Vermelho Amarelo Distrófico. As cultivares de soja, BRS Jiripoca e BRSMT Uirapuru, receberam as seguintes doses de fósforo: 0, 36, 72, 110, 144 e 177 kg ha-1 de P2O5, na forma de superfosfato simples. O delineamento experimental utilizado foi o inteiramente casualizado com três repetições, e os tratamentos arranjados em fatorial 6 x 2. Foi avaliado a altura de plantas, a altura de inserção da primeira vagem e o rendimento de grãos. Não há diferença entre cultivares de soja, BRSMT Uirapuru e BRS Jiripoca, para a resposta as dose de fósforo na altura de plantas. As doses de fósforo não interferem na altura de inserção da primeira vagem. Há respostas positivas em rendimento de grãos devido ao aumento das doses de fósforo em solos pobres deste nutriente.Palavras-chave: Glycine max, inserção da primeira vagem, rendimento de grãos. ABSTRACTThe soybean response to phosphorus (P) application in soils with P content below the critical level is inversely proportional to the available P of the soil. The objective of this paper was evaluate some response parameters of soybean cultivated in soil with low content of phosphorus, submitted at different rates of phosphorus fertilization. The experiment was located in Rolim of Moura, Rondônia state, in a Oxisol. BRS Jiripoca and BRSMT Uirapuru soybean cultivars received six rates of phosphorus fertilizer, 0, 36, 72, 110, 144 and 177 kg ha-1 of P2O5. The experiment was in a completely randomized design with three replications, and the treatments arranged in factorial 6 x 2. It was evaluated the height of plants, the height of first pod insertion and the grain yield. There is no difference between cultivars of soybean BRSMT Uirapuru and BRS Jiripoca to the answer of quantities of phosphorus in the height of plants. The quantities of phosphorus do not interfere on the height of first pod insertion. There are positives answers in grain yield due to increase the quantities of phosphorus in poor soils of this nutrient.

Secondary crop cultivation is very important for producers of corn and beans crops worldwide, and can reach high levels of productivity. The study aimed to evaluate water use efficiency and grain yield response of corn and bean species cultivated in a secondary crop system, when subjected to different water levels. Two experiments were carried out, one for the corn cultivar DKB 240 and another for the bean cultivar IPR Gralha; the study was developed in an experimental area classified as Oxisol typical, both experimental designs consisted of a randomized single factor block design with five water levels (0, 50, 75, 100 and 125% of reference evapotranspiration; Eto) with three replications. The following variables were analyzed: number of rows per ear, number of grain per row, thousand grain mass and grain yield for corn; number of pods per plant, number of seeds per pod, thousand grains mass and grain yield for beans. Water use efficiency was calculated as the relationship between grain yield and the applied water level. The corn and bean crops had the highest water use efficiency in the levels of 100% and 125% of reference evapotranspiration, respectively. These levels showed the highest yield of crops. Both corn and beans can be recommended for planting in the second crop system as they present a high yield potential under favorable water conditions; in order to meet water demands, they require a total of 413.53 mm for corn and 447.12 mm for the bean cultivar distributed throughout the crop cycle.