Edson Alves Bastos

Tolerância ao déficit hídrico em genótipos de feijão-caupi

ABSTRACT The objective of this study was to evaluate physiological and productive characteristics of cowpea underwater deficit and total irrigation, under soil and climate conditions of Teresina, Piaui State, in 2008. Thestomatal conductance, leaf water potential, leaf temperature and grain yield of twenty cowpea cultivarswere evaluated. Two experiments were carried out in a randomized block design with 20 treatments andfour replications, one under water deficit during the reproductive phase and another one under totalirrigation. The water deficit was obtained applying half of the water depth required by cowpea. The waterdeficit reduced 72% of the stomatal conductance, 40% the leaf transpiration, 62% of the leaf waterpotential, 60% of the grain yield and increased 11.7% the leaf temperature. Under water deficit, 13genotypes produced above average (466 kg ha -1 ), and BRS-Paraguacu, Pingo-de-ouro-1-2 andPingo-de-ouro-2 presented the best grain yield with712 kg ha -1 , 667 kg ha -1 and 642 kg ha

Uso e qualidade da água subterrânea para irrigação no semi-árido piauiense

The semi-arid region in the State of Piaui, Brazil, is characterized by low rain fall and high evapotranspiration. However, the groundwater reserves make possible the economic development by underground hydrogeology characteristics, which allow extractions of high water flow with good quality, in most of the cases. However, some wells reached formations that have low discharge and water with high salt concentration, which if used for irrigation may cause salinization and sodification. The main goal of this work was to characterize the different uses and quality of groundwater in a part of the semi-arid area of Piaui, with a view to its use for irrigation. Samples were collected in 225 wells distributed spatially in the area, in which the following variables were analyzed: electrical conductivity, Na, Ca, Mg, SAR, CO3, HCO3, Cl and SO4. Regarding water use, the domestic use prevailed (53.61%), followed by irrigation (21.17%), with the following irrigation methods: drip irrigation (14.03%); microsprinkler (3.83%); conventional sprinkler (16.11%); gun sprinkler and traveler irrigation machine (13.66%); surface irrigation (16.76%) and other handmade methods (35.52%). The maps of classes of use risk irrigation generated from groundwater quality showed the occurrence of sub-areas with the following classes: no restriction, moderate restriction and severe restriction.

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.

Identification of cowpea genotypes for drought tolerance

The genotypes selection for drought tolerance is very important for world food production, principally in arid regions or sites with irregular rain distribution. The objective of this work was to identify cowpea genotypes with drought tolerance and water stress sensitivity characteristics. Two experiments were carried out with 20 treatments and four replications, one under water deficit during reproductive phase and another one under full irrigation. The water deficit was obtained applying half the water depth required by cowpea. The leaf area index, chlorophyll content, grain components and grain yield were evaluated. The water deficit reduced 20% the leaf area index, 16% the chlorophyll content, 175% the pod number per plant and 60% the grain yield. The genotypes Santo Inacio and Tracuateua-192 present sensitivity to water deficit in soil andBRS-Paraguacu, Pingo-de-ouro-1-2 and Pingo-de-ouro-2 show behavior for drought tolerance.

Estratégias ótimas de irrigação do feijão‑caupi para produção de grãos verdes

The objective of this work was to determine optimal strategies of irrigation for cowpea (Vigna unguiculata) for the production of green bean, with water as the limiting yield factor and different values for the price of the product. The experiment was carried out at Embrapa Meio‑Norte, in Teresina, PI, Brazil, from September to November 2009. Five irrigation depths, established based on fractions of reference evapotranspiration (25, 50, 75, 100, and 125% of ETo), and the BRS Guariba and BRS Paraguacu cowpea cultivars were evaluated. Irrigation was done with a conventional fixed sprinkling system. The experimental design was a randomized complete block with four replicates, in a split‑plot arrangement (cultivars). The irrigation depths from 290 to 325 mm (108 to 130% of ETo) (BRS Paraguacu) and from 325 to 363 mm (130 to 153% of ETo) (BRS Guariba) maximize the liquid income, considering the price range of the product from US

Evaluation of maize core collection for drought tolerance

0.75 to 2.00 kg‑1, for the cultivar BRS Paraguacu, and from US

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

0.50 to 2.00 kg‑1, for BRS Guariba. The cultivar BRS Guariba shows better economic performance than BRS Paraguacu.

Water storage in a Plinthaqualf cultivated with sugarcane under straw levels

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.

Selection of cowpea populations tolerant to water deficit by selection index

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.

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

The objective of this work was to evaluate water storage in a Plinthaqualf under different straw levels during the fourth ratoon season of a sugarcane (Saccharum officinarum) crop. The study was conducted in the 2013/2014 crop season, with the cultivar SP-813250, at two soil depths (0.0–0.3 and 0.3–0.6 m), in a randomized complete block design, with five straw levels (0.0, 4.2, 9.5, 13.0, and 18.4 Mg ha-1) and four replicates. Soil moisture content was monitored with a time-domain reflectometer. The straw provided gains of up to 20 Mg ha-1 stems and kept increased water storage in the soil, in comparison with the soil without straw, in all evaluated periods. Maintenance of up to 50% (9.5 Mg ha-1) of sugarcane straw on soil surface promotes better water retention in the soil per Mg of straw added and delays the reach of critical water storage in the soil by up to 11 days, when compared with soil without straw cover.