M. J. Cardoso

Adaptabilidade e estabilidade de cultivares de milho no nordeste brasileiro

Forty six maize cultivars were evaluated during two years in 11 different places of Brazilian Northeast Region. Trials were carried out during the biennium 2001/2002 using experimental randomized block design, three repetitions, in order to know the adaptability and stability for cultivars recommendation. It was verified that the cultivars showed differentiated behavior among themselves in the mean of environments. The magnitude of the variance for local x cultivars interaction was more expressive than cultivars x years interaction, which suggests that the evaluations have to be done in a larger number of environments. Evaluated cultivars differed in adaptability and stability, and are very important for Brazilian Northeast Region.

Níveis de irrigação na cultura do feijão caupi

This work was carried out to evaluate the effect of irrigation depth on yield and production components of cowpea (Vigna unguiculata L. Walp) under soil and climatic conditions of the Coastal Tablelands in the State of Piaui - Brazil. The trial was conducted at the Embrapa Meio-Norte Experimental Area, in Parnaiba, in a sandy soil, during the period from August to October, 1998. Irrigation depths were applied through a sprinkler line source system. The treatments were constituted by combination of four depths of irrigation (449.1; 428.6; 317.1 and 194.4 mm) and two cowpea cultivars (BR 17 Gurgueia and BR 14 Mulato) arranged in a completely randomized block design in split-plot and five replications. Significant effects (p<0.05) of depth of irrigation and cultivar interaction with respect to number of pods per plant (NPP) and grain yield (GY) were observed. The highest NPP (25.6) and maximum GY (2,809 kg ha-1) for the BR 17 Gurgueia cultivar was obtained with the irrigation depth of 449.1 mm. The maximum NPP (15.0) and GY (2,103.4 kg ha-1) for the BR 14 Mulato cultivar were obtained with the irrigation depth of 363.5 and 389.9 mm, respectively.

Fertilização nitrogenada, densidade de plantas e rendimento de milho cultivado no sistema plantio direto

Pesquisador Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA) Meio Norte, BR-64006220 Teresina, PI, Brazil

Estoques de C e de N e produtividade do milho sob sistemas de preparo e adubação nitrogenada em um Latossolo Vermelho-Amarelo do cerrado piauiense

Total soil organic carbon (C) and nitrogen (N) stocks and crop yield are influenced by tillage, biomass input from crop and nitrogen fertilization. This research aimed to evaluate the effect of different tillage systems associated to nitrogen doses on corn yield and C and N stocks in the Red Yellow Latosol in savanna of Piaui state, Brazil. The experiment was carried out in Baixa Grande do Ribeiro, south of Piaui state. The treatments were distributed in a randomized complete blocks and factor arrange 2x5, two tillage systems (no-tillage (NT) and conventional (CT)) and five nitrogen doses (0, 60, 120,180 and 240kg ha-1 N), respectively, with six replications. The corn grain yield (GY) and C and N inputs were measured and C and N soil stocks were evaluated in the 0-5, 5-10, 10-20 and 20-40cm. N doses caused a quadratic response in the grain yield, C and N inputs from maize crop and soil C stocks in both tillage systems. Higher GY were obtained by 138 and 134kg N ha-1 to CT and NT, respectively. Higher C and N inputs were obtained by 140 and 175kg N ha-1, in the CT and by 139 and 100kg N ha-1 in the NT system, respectively. Nitrogen fertilization increased soil C stocks in the NT comparing to CT in the 0-5 and 5-10 depths. No tillage adoption combined with balanced nitrogen fertilization can be important to soil organic matter production in soils under cerrado of Piaui state.

Adaptabilidade e estabilidade de produção de cultivares de milho no nordeste brasileiro

Twenty five cultivars of maize (Zea mays L.) were evaluated in 1994, in twelve different environments of the Northeast Region of Brazil. The trials were arranged in randomized block designs with three replications aiming to obtain knowledge concerning to the adaptability and yield stability of the cultivars in each environment. The significant effects related to environment, cultivars and cultivars x environments interaction gave the evidence of outstanding differences among that parameters. The hybrids showed better performance than the varieties, yielding in average 22.5% higher in relation to the environmental variations. Only the Cargill 505 and AG 510 hybrids showed poor adaptability in unfavorable environments. Taking in account the means presented by the varieties, CMS 39 was the most adjusted to the optimal genotype proposed in the model. None of the materials studied gave a determination coefficient (R2) lower than 80%, indicating a good production stability.

Evaluation of maize core collection for drought tolerance

The maize genebank (GBmaize) preserves nearly 4,000 accessions for conservation and use. The use is however restricted because the accessions do not perform as well as the elite genotypes. This problem can be reduced by pre-breeding, i.e., by extending the information on germplasm and introgressing useful alleles. Since irregular rainfall distribution and drought induce maize yield losses, drought tolerance is a main breeding target. In this study, the GBmaize accessions were evaluated for drought tolerance. Environmental factors, genotypes and the respective interactions influence the phenotypic expression. There was however no interaction genotype - irrigation level, so no accessions with different performance under the two water regimes could be identified. The performance of the following accessions was promising for a number of traits: SP154, BA166, MG099, CE002, SE025, BA154, BA194, BA085, MG076, PR053, Roxo Macapa, SE016, and AL018.

Produtividade de grãos verdes do feijão-caupi sob diferentes regimes hídricos

The objective of this study was to evaluate green grain yield, production components and water use efficiency for cowpea-bean under different water regimes. The experiment was carried out at Embrapa Meio-Norte, in Teresina, PI, Brazil, from September to November 2009. Five irrigation blades, based on reference evapotranspiration fractions (25, 50, 75, 100, and 125% of ETo), and the evaluated cowpea-ben cultivars were BRS Guariba and BRS Paraguacu.Irrigation was performed by conventional fixed sprinkling system. The experimental designwas a randomized complete blockwith four replicates, in a split-plot arrangement (cultivars). Maximum green grain yields achieved 2,937.3 kg ha-1 for BRS Guariba and 2,492.9 kg ha-1 for BRS Paraguacu; these productivities were obtained under 354 mm and 423 mm irrigation blade, respectively. The irrigation blades of 275 mm and 231 mm for BRS Guariba and BRS Paraguacu cultivars, respectively, accomplished the most efficiency in water use for green grain yield. BRS Guariba shows a better performance compared with BRS Paraguacu.

Baby corn, green corn, and dry corn yield of corn cultivars

In corn, when the first female inflorescence is removed, the plant often produces new female inflorescences. This allows the first ear to be harvested as baby corn (BC) and the second as green corn (GC) or dry corn (DC), that is, mature corn. The flexibility provided by a variety of harvested products allows the grower to compete with better conditions in the markets. We evaluated BC, GC, and DC yields in corn cultivars AG 1051, AG 2060, and BRS 2020, after the first ear was harvested as BC. A random block design with ten replicates was utilized. The yields of MM, MV and MS were higher when these products were individually harvested than when they were harvested in combination with baby corn (BC + GC and BC + DC). Cultivar BRS 2020 was the best for producing BC exclusively, considering the number and weight of marketable unhusked ears and the number (NH) of marketable husked ears. Considering weight (WH) of BC marketable husked ears, cultivar AG 1051 was the best. Cultivars did not differ in baby corn yield when this product was harvested in combination with MS or MV, except with regard to NH and WH, with AG 1051 being superior. The cultivars did not differ between total number of ears and number of marketable unhusked green ears. However, cultivars AG 1051 and AG 2060 were the best with respect to marketable unhusked green ears and number and weight of marketable husked green ears. Cultivar AG 1051 was the best with regard to kernel yield.

Zinc fertilization in cowpea cultivars

Zinc (Zn) is an essential micronutrient for plants, due to its role as a functional, structural, or regulatory cofactor in a large number of enzymes. The element is necessary for the synthesis of tryptophan, which is a precursor of indoleacetic acid. The aim of this study was to evaluate the behavior of two cowpea cultivars fertilized with four doses of Zn (0.0, 2.0, 4.0, and 6.0 kg of Zn ha-1) regarding dry grain yield (PGS), in addition to quantifying leaf and grain Zn content and grain crude protein. The experiment was conducted in the town of Brejo, in the state of Maranhao, Brazil. A 4 x 2 factorial scheme was used with four replications. Response functions were adjusted by calculating the Zn doses which provided a maximum technical efficiency for each genotype. The tested cultivars of cowpea showed no great difference regarding Zn demand applied to the soil, ranging from 3.2 to 3.4 kg of Zn ha-1 for BRS Tumucumaque and BRS Guariba, respectively. Concerning Zn use efficiency, BRS Guariba was more responsive than was BRS Tumucumaque, i.e. the same dose of Zn produced 70 kg grain and 2.1 kg crude protein per hectare.

Agronomic performance of the cowpea under different irrigation depths and row spacing

The cowpea is of great socioeconomic importance in the North, Northeast and Mid-West of Brazil, and its irrigated farming has recently been on the increase in these regions. The aim of this study was to evaluate the agronomic performance of the cowpea ‘BRS Tumucumaque’ for different row spacings and irrigation depths, under the conditions of soil and climate of Teresina, in the State of Piaui. The experiment was carried out from August to November 2014, in a Yellow Argisol at the Experimental Area of Embrapa Meio-Norte in Teresina. The experimental design was of randomised blocks in subdivided lots, with four replications. The treatments consisted of five irrigation depths (40% ETo, 70% ETo, 100% ETo, 130% ETo and 160% ETo) in the main plot, and four spacings between rows (0.36 m, 0.45 m, 0.60 m and 0.90 m) in the sub-lots. Leaf area index, pod length, number of grains per pod, number of pods per plant and grain productivity were evaluated. There was significant interaction (p<0.01) between irrigation depth and row spacing for grain productivity only. There was a significant increasing linear effect (p<0.01) from irrigation depth on pod length, number of pods per plant and number of grains per pod. The larger irrigation depths at the smaller row spacings give the greatest grain productivity. With leaf area index, there was a significant effect from irrigation depth and row spacing for the periods under evaluation.