João Bosco Pitombeira

Controle de plantas daninhas em feijão-de-corda em sistema de semeadura direta

O objetivo deste estudo foi avaliar a eficiencia dos herbicidas glyphosate (1.800 g ha-1) e paraquat (800 g ha-1), aplicados antes da semeadura como dessecantes, e imazamox (0, 21, 42 e 63 g ha-1) ou fenoxaprop-p-ethyl (0, 40, 80 e 120 g ha-1), aplicados em condicoes de pos-emergencia, no controle das plantas daninhas, bem como os efeitos toxicos ao feijao-decorda (Vigna unguiculata cv. Epace 10), em sistema de semeadura direta com irrigacao. Utilizou-se o delineamento experimental em blocos ao acaso, com os tratamentos arranjados em parcelas sub-subdivididas, com quatro repeticoes. Os tratamentos com glyphosate associado a imazamox ou fenoxaprop-p-ethyl resultaram em menor infestacao das plantas daninhas, avaliadas atraves da fitomassa seca da parte aerea, maior producao de graos e maior numero de vagens por planta de feijao-de-corda, quando comparado com os tratamentos com paraquat associado aos herbicidas pos-emergentes. Os herbicidas imazamox e fenoxaprop-p-ethyl nao causaram sintomas visuais de toxicidade ao feijao-de-corda. A dose de 80 g ha-1 de fenoxaprop-p-ethyl associada com o glyphosate (1.800 g ha-1) foi a mais eficiente no controle das plantas daninhas, na avaliacao realizada 45 dias apos a aplicacao (DAA) do fenoxaprop-p-ethyl. Este herbicida nao controlou o capim-carrapicho (Cenchrus echinatus) e o capim-colchao (Digitaria horizontalis) nas avaliacoes realizadas aos 15 e 28 DAA. O imazamox nao foi eficaz no controle das especies erva-de-santa-luzia (Chamaesyce hirta) e leiteira (Euphorbia heterophylla).

Controle químico de plantas daninhas na cultura do arroz irrigado no estado do Ceará

A field experiment was conducted, during the dry season of 1995, on alluvial soil of the Vale do Curu Experimental Farm, State of Ceara, Brazil, in order to evaluate the effect of the herbicides: propanil (4.8 kg a.i.ha-1), fenoxapropethyl (0.14 kg a.i.ha-1), fenoxaprop-p-ethyl (0.11 kg a.i.ha-1), oxadiazon (0.62 kg a.i.ha-1) and the mixtures propanil + molinate (2.52+2.52 kg a.i.ha-1 ) and propanil + 2,4-D (2.72+0.22 kg a.i.ha-1) on the control of weeds in rice, cultivars METICA-1 and CICA-8, growing under flood irrigation. The best weed control and paddy rice yield were provided by propanil and the mixtures propanil + 2,4-D and propanil + molinate. Plant height, days to flowering, head size and the weight of 1000 seeds were not affected by the herbicides. The symptoms of toxicity caused by the herbicides on the rice plants of the two cultivars were slightly severe.

Agronomic and biological efficiency in the castor bean intercropped with cowpea or maize

Objetivou-se com o presente trabalho avaliar a eficiencia agronomica e biologica dos consorcios de mamoneira com feijao-caupi ou milho. As pesquisas foram desenvolvidas na Fazenda Experimental Lavoura Seca, da Universidade Federal do Ceara, em Quixada-CE. Foram avaliados os consorcios entre plantas de mamoneira cv. BRS Energia com feijao-caupi cv. Setentao (I) ou com milho cv. BRS 206 (II). Os tratamentos consistiram da combinacao entre duas culturas em duas densidades populacionais (5.000 e 10.000 plantas por hectares de mamoneira; 20.000 e 40.000 plantas por hectares do consorte) mais dois cultivos solteiros, que foram distribuidos em quatro blocos casualizados. Avaliou-se a produtividade das culturas, uso eficiente da terra, indice de competitividade e requerimento minimo exigido pelas culturas consortes. Os dados de produtividade foram submetidos a analise de variância e as medias comparadas por meio de contrastes. Os indices biologicos foram interpretados a partir dos valores parciais de uso eficiente da terra plotados em um plano cartesiano. Os sistemas de cultivo afetaram a produtividade da mamoneira, do feijao-caupi e do milho. Tambem foram observados efeitos dos consorcios e das densidades populacionais da mamoneira e das culturas consortes nos indices de uso eficiente da terra e competitividade. As produtividades da mamoneira e dos consortes sao reduzidas quando consorciadas. O consorcio entre feijao-caupi e mamona e eficiente no uso da terra. Na consorciacao da mamoneira com milho ha eficiencia no uso da terra apenas com as maiores populacoes da oleaginosa. No consorcio mamona com feijao-caupi a cultura dominante e influenciada pela densidade das culturas, enquanto o milho e mais competitivo que a mamoneira.

Effect of spatial arrangement on the production components and yield of sunflower

The sunflower plant is an oilseed crop that has aroused a great interest in the Brazilian and international scenery especillay because of the possibility of using its oil for biodiesel production. The objective of this study was to evaluate productivity and yield components of Embrapa 122 sunflower according to the spatial arrangement. Treatments were arranged in 4 x 4 factorial arrangement, which are the four spacings between rows (0.30; 0.50; 0.70 and 0.90 m) and four sowing densities (30,000; 45,000; 60,000 and 75,000 plants ha-1). The experiment was carried out in a complete randomized block design with four replications. The experiments were conducted in the experimental area of the Plant Science Department in Fortaleza, State of Ceara-Brazil and on the Curu Vale Experimental Farm in Pentecoste, State of Ceara-Brazil. Productivity and the following production components were analyzed in the end of the crop cycle: harvested capitula, capitulum diameter, capitulum mass, achene mass per capitulum, mass of 100 achenes, achenes per capitulum, harvest index and oil content in the achenes. The experiments were analyzed jointly in relation to the cropping area and the data submitted to analysis of variance and quantitative factors tested by polynomial regression. The variables, spacing, density and cropping area did not interact with these variables and the spatial arrangement of the plants affected only the components. The cropping area influences the productive behavior of sunflower Embrapa 122. The spatial arrangement of the plants of sunflower of variety Embrapa 122 influences yield components but does not affect productivity.

INFLUÊNCIA DA COBERTURA MORTA NA PRODUTIVIDADE DE MILHO E FEIJÃO-CAUPI EM SISTEMA PLANTIO DIRETO

The success of no tillage system is directly related with the remaining of crop residues on soil surface, the quality and quantity of straw and its mineralization promoting recycling of the nutrients. The aim of this study was to evaluate the contribution of straw from spontaneous vegetation, millet (Pennisetum americanum sin. tiphoydes), brachiaria (Brachiaria brizantha); sorghum forage (Sorghum bicolor L Moench), and the straw from conventional tillage, on corn and cowpea grain yield under two minimum tillage systems: SPD1 (corn following cowpea) and SPD2 (cowpea following corn), under the semiarid conditions of the Quixada County, Ceara, Brazil, during 2008 and 2009. It was evaluated also the period of duration of the straw on soil surface and the rate of decomposition of the straw from corn and cowpea. The straw yield from spontaneous vegetation was around 6.0 t ha-1 similar to the yield of the others soil biomass covers in both SPD1 and SPD2 minimum tillage systems. The degradation of the vegetal residues to the soil at the end of two years of evaluation was greater when the dry matter from cowpea was used as straw when compared with the straw from corn. The grain yield of corn from the different death cover was significantly lower than the conventional in 2008 and 2009. The cowpea yield was higher from conventional planting than from than the minimum tillage with different straw covers.

MAMONA E GIRASSOL NO SISTEMA DE CONSORCIAÇÃO EM ARRANJO DE FILEIRAS: EFICIÊNCIA BIOLÓGICA

An experiment field was carried in the agricultural seasons 2008, 2009 and 2010, with aim of studying the response of castorbean (Ricinus communis L.) intercropping with sunflower (Helianthus annus L.) in row arrangement in the dryland farming conditions. In addition, it was evaluated the biological efficiency of plants in intercropping systems.The design used in the experiment was randomized block with seven treatement and four replications. The treatments were represented by rows of castor oil (Ma) and sunflower (Gi) listed below: 1Ma:1Gi; 1Ma:2Gi; 1Ma:3Gi; 2Ma:2Gi; 2Ma:3Gi; castor and sunflower in the monoculture. The efficiency of intercropping was measured by LER, ATER, LEC, average between LER and ATER, SPI and CoR. The grain yield of castor bean and sunflower were reduced in intercropped row arrangements. The row arrangement 1Ma:2Gi showed the smallest reduction of average productivity of castor beans and sunflower in the evaluation period of the experiment. The castor bean was the dominant crop in relation to sunflower.