Robert Deuber

Efeitos de herbicidas na anatomia de capim-carrapicho e amendoim-bravo

Cenchrus echinatus L., seeded in pots at a depth of four cm, was treated with trifluralin at 0.84 kg/ha, incorporated at depths of 0 to 3 and 5 to 11 cm. Euphorbia heterophylla L, seeded at a depth of one cm, was treated with trifluralin at the same rate, incorporated from 0 to 8 cm, pendimethalin at 1.15 kg/ha and 2.4-D, amine, at 1.44 kg/ha at surface, in preemergence. The plants were observed during the two first weeks and after this material was collected and microscopic observations were made on the affected tissues. Trifluralin enlarged the root tip and the coleoptile diameter, inhibiting their growth in C. echinatus. Swelling of cortical cells was observed. The cells had thinner walls and sometimes were multinucleate. In E. heterophylla there was lateral root inhibition and little swelling of cortical cells. Pendimethalin caused great thickening of the transition zone in E. heterophylla, due to swelling of cortical and epidermal cells, which had thinner walls. Small lateral root inhibition occured. The 2.4-D affected tissue formation, originating cells in the pith center. In some plants an epidermal dislocation was observed.

Análise de crescimento e trocas gasosas na cultura de milho em plantio direto e convencional

GROWTH ANALYSIS AND GAS EXCHANGES IN CORN CULTIVATED IN NO TILLAGE AND CONVENTIONAL CROPPING Each cropping system acts in a particular way on soil characteristics and may affect crop growth differently. In this research the effects of no tillage (NT) and conventional system (CS) on corn cultivated after triticale, were evaluated by using growth analysis and gas exchanges. The experimental design was completely randomized block with plots (cropping system) and sub-plots (sampling dates) with six replications. The primary data of dry matter and leaf area were collected from all plants in one meter row which were, cut at the level of the soil, every 15 days. Crop growth rate (CGR), net assimilation rate (NAR) and leaf area index (LAI) rate were evaluated. Measurements of gas exchanges [CO2 assimilation (A); transpiration (E) and stomatic conductance (gs)] were take using photosynthesis a portable analyzer at 36, 49, and 80 days after the seedling emergence, at the stage V8, VT and R4, respectively. LAI and CGR, total dry matter, dry matter of stems, ears and grains were higher in CS. The gas exchanges did not showed any differences between the cropping systems. The occurrence of water deficiency in February and March causes reduction of A, gs and E. The differences observed in CS were related to the faster growth and higher LAI.

Manejo de plantas daninhas em beterraba com metamitron e sua persistência em Argissolo

In order to study weed control efficiency and soil persistence, a field experiment was carried out in Ultisol-Kandiucult with table beet (Beta vulgaris L.) cultivar Tall Top. The treatments were: metamitron applied in pre-emergence at 2,8; 3,5 and 4,2 kg.ha-1 a.i, plus two controls, one weeded and another always with weeds, in a randomized block design with four replications. Weed control and selectivity were evaluated at 28 and 70 days and persistence in soil at 0, 21, 49 and 70 days after treatments (DAA), with bioassays using lettuce (Lactuca sativa L.) cultivar Elisa Crespa. The main weeds occuring in the trial were Eleusine indica (L.) Gaertn, Galinsoga parviflora Cav. and Coronopus dydimus (L.) Sm. Metamitron at the applied rates was apparently selective to table beets, considering the leaves. G. parviflora and C. dydimus were efficiently controlled with any of the applied rates up to 70 DAA. E. indica was well controlled until 28 DAA with all rates and until 70 DAA only with 3,5 and 4,2 kg.ha-1. Residual activity for 2,8 and 3,5 kg, lasted until 70 DAA, but for 4,2 kg it was longer. Chemical weed control improved yield with an increase on table beet roots of commercial type.

Lixiviação de metribuzin, oxadiazon e bromacil em dois tipos de solos

The leaching of metribuzin, oxadiazon and bromacil in two soils and simulated rainfalls of 60 and 120 mm of water was studied in columns. Columns with 10 cm diameter and 21 cm height, divided in sections of 3 cm were used. After the water percolated through the sections were separated and Lactuca sativa was sown in those with metribuzin and bromacil and Echinochloa cruzgalli in those with oxadiazon. Dead plants were counted every two days after emergence during two weeks and during ten days after a second sowing. An expression relating dead and living plants and the time plants took to die was used to estimate the concentration of the herbicides in each section of the columns, for each counting. Oxadiazon remained in the first 3 cm of the column for any condition studied. Metribuzin reached 9 cm in clay soil with 60 mm of water and 18 cm with 120 mm. In the loam soil it reached 21 cm with both precipitations. Bromacil showed more intense leaching than metribuzin in any conditions with lower retention in the upper sections with 60 mm. The differences of leaching between the two soils seem to be due more to the content and type of clay and less to the content of organic matter.

Efeito de extratos aquosos de estruturas de grama-seda no desenvolvimento inicial de plântulas de arroz, milho e trigo

ABSTRACT EFFECTS OF AQUEOUS EXTRACTS OF BERMUDAGRASS STRUCTURES ONINITIAL GROWTH OF RICE, CORN AND WHEAT SEEDLINGS The objective of this work was to study the effects of aqueous extracts of Bermudagrass structures( Cynodon dactylon (L.) Pers) and soil exudates, on the germination and initial growth of rice, corn andwheat seedlings. The aqueous extracts of above-ground and subterranean parts and of the whole plant, aswell as of stolons, leaves + culm, stolons + leaves + culm, rhizome, root and rhizome + root of Bermudagrass,were prepared from 100 g L -1 of dry plant material. It was also investigated if these extracts and the oneobtained from soil removed from the rhizosphere of the subterranean plant parts, and of the stolons wouldshow any interference. Inhibition or stimulation of the initial seedling development was dependent onthe tested species and the structure employed in the preparation of the extract. Radicle protrusion wasinhibited more than radicle and plumule growth. The stimulus of radicle and plumule growth was moreevident when the extract was prepared from the root system structures, above-ground plant parts and wholeplant than from the separated plant structures of Bermudagrass. Rice and corn were more inhibited byextracts prepared from the above-ground and subterranean plant part respectively. Wheat inhibition orstimulation effects were dependent on the variable analysed. The development of radicle and plumule ofrice, corn and wheat was stimulated by extract prepared from the whole plant. The extract prepared fromthe clay + silt soil fraction in which the grass grew stimulated growth of corn radicle and wheat plumule.

Interacao de imazapic no sistema integrado palha de cana-de-acucar, herbicida e vinhaca no crescimento inicial da tiririca

The objective of this paper was to evaluate sugarcane mulch residue, imazapic and vinasse application interaction on the initial development of purple nutsedge (Cyperus rotundus L.). A greenhouse experiment was set up using pots filled with soil, arranged in a randomized complete blocks design, with four replications, with the following treatments: check; straw alone; vinasse alone; imazapic alone; straw + vinasse; straw + herbicide; herbicide + vinasse applied before the herbicide; herbicide + vinasse applied together; straw + herbicide + vinasse applied after the herbicide; straw + herbicide + vinasse applied after the herbicide; and straw + herbicide + vinasse applied together. Imazapic was applied at the rate of 122.5 g ha-1 and in the treatment in which vinasse was applied mixed with the herbicide, this compound was diluted in water until ¼ of the volume needed, the remaining volume being completed with vinasse. Imazapic was efficient for purple nutsedge control when compared to the check. Application of vinasse alone or straw alone stimulated the growth of this weed, though tuber viability was reduced. In the treatments without straw there was no difference in purple nutsedge development when vinasse was applied before or after imazapic, though control of this weed species was attained. However, when mixed with vinasse, the herbicide did not control the weed. The presence of straw in the treatment in which vinasse was applied before imazapic reduced the action of this weed killer when compared with the treatment without straw. The number of sprouts and height of the purple nutsedge plants were enhanced by the treatments with straw when imazapic was applied after or even mixed with vinasse. Only the number of sprouts increased when vinasse was applied after or mixed with the herbicide in soil covered with straw.

Controle de plantas daninhas e efeitos de herbicidas na cultura de Gladiolus

O controle de plantas daninhas e a tolerância de gladiolos, cultivares Spick and Span e White Friendship, a tratamentos herbicidas foi estudado em um experimento de campo em solo areno-argiloso. Foram aplicados os herbicidas trifluralin e EPTC em pre-plantio com incorporacao e chloroxuron, DCPA, diphenamid, pendimethalin e diuron em pre -emergencia. Houve maior incidencia de gramineas que foram controladas por todos os herbicidas, exceto chloroxuron, sendo o controle pelo EPTC de 83% e pelos demais, acima de 90%. Para as dicotiledoneas, o controle foi na seguinte ordem decrescente: pendimethalin, chloroxuron, diuron, trifluralin, EPTC, DCPA e diphenamid. O EPTC afetou a germinacao de bulbos, causando, tambem, retencao de crescimento e atraso no ciclo. No florescimento, as hastes florais foram colhidas, medidas e pesadas, verificando-se reducao significativa de peso de materia fresca com o tratamento EPTC para o cultivar Spick and Span, e com trifluralin, EPTC, chloroxuron e pendimetha lin para o White Friendship.

Control of nutsedge (Cyperus rotundus L: ) with sucess1ve applications of EPTC on beans

Estudou-se o controle da tiririca (Cyperus rotundus L.) por meio de aplicacoes sucessivas de EPTC, uma e duas vezes ao ano, por dois anos. Aliou-se a eficiencia do produto contra a tiririca a sua seletividade ao feijoeiro (Phaseotus vulgaris L.), cv. carioca. As doses variaram desde 0 a 21,6 kg/ha do ingrediente ativo, sendo que a dose maxima nao se mostrou esterilizante do solo, nem com duas aplicacoes ao ano, o que se verificou pela populacao de carrapicho-de-carneiro (Acanthospermum hispidum DC) e serralha-falsa (Emilia sonchifolia L.). Houve reducao gradativa e significativa da populacao de tiririca, com duas aplicacoes por ano, em todas as doses. Nas mais elevadas verificou-se reducao total apos dois anos. Com uma aplicacao por ano, nas doses mais elevadas, houve recuperacao parcial, e nas mais baixas, recuperacao total. As producoes e a qualidade da cultura nao foram afetadas pelo herbicida. Houve aumento de producao com a elevacao da dose na segunda e quarta safras, devido, aparentemente, a eliminacao da competicao da tiririca.

Local de ação de trifluralin na germinação de capim-carrapicho

Foram conduzidos estudos em vasos e no campo, para conhecer ate que profundidade ocorria germinacao de capim-carrapicho (Cenchrus echinatus L.). Em vasos esta ocorreu ate 11 cm de profundidade e no campo ate 9 cm em solo argiloso, e 10 cm em solo barrento. Foi frequente a germinacao de duas ou mais cariopses por infrutescencia. Em dois outros testes em vasos foi estudado o local de acao do trifluralin na dose de 0,84 kg/ha de i.a., em solo barrento. Verificou-se acao do herbicida nas zonas meristematicas da raiz e do coleoptilo, causando inibicao de desenvolvimento longitudinal do mesocotilo e da raiz. Na ponta da raiz primaria, no primeiro no e no coleoptilar verificou-se aumento pronunciado de diâmetro.

Herbicidas no transplante de mudas de sisal (Agave sisalana perr.)

The weed control with herbicides and its selectivity to sisal were studied on a clay soil field trial. The treatments (in a.i./ha) were: 0.84 and 0.96kg of pre-plant incorporated trifluralin; 2.40 and 3.26kg of alachlor; 0.70 and 0.84kg of metribuzin; 1.60 and 2.40kg of bromacil; 1.60 and 2.40kg of terbacil; 2.40 and 3.20k- of diuron; 3.20 and 4.00kg of simazine; 1.20 and 1.60kg of fluometuron; a hoed check and a not hoed check. Trifluralin was applied on September 24, 1976, the bulbils were transplanted on the 29th of the same month and the PRE herbicides applied on the 30th. Weed control was evaluated at 67 and 114 days after PRE application. The grass control was over 90% by trifluralin, bromacil and terbacil, around 80% by simazine and below 75% by the remaining herbicides. The broadleaves were controlled at a level of 90 to 100% by bromacil and terbacil and 80 to 85% by simazine. None of the herbicides affected the growth of sisal plants during the considered period of 600 days. At 550 days the area covered by weeds was evaluated. Terbacil controlled still 75 and 95% of the total quantity of weeds, at the lower and higher doyes, respectively, trifluralin controlled 60 to 70% and the remainder below 45%. For final evaluation at 600 days, crop stand, number of plants with sprouts, number of leaves per plant and crop condition were considered. The treatments with best weed control also showed the best scores for crop development, partly due to their selectivity to sisal.The weed control with herbicides and its selectivity to sisal were studied on a clay soil field trial. The treatments (in a.i./ha) were: 0.84 and 0.96kg of pre-plant incorporated trifluralin; 2.40 and 3.26kg of alachlor; 0.70 and 0.84kg of metribuzin; 1.60 and 2.40kg of bromacil; 1.60 and 2.40kg of terbacil; 2.40 and 3.20k- of diuron; 3.20 and 4.00kg of simazine; 1.20 and 1.60kg of fluometuron; a hoed check and a not hoed check. Trifluralin was applied on September 24, 1976, the bulbils were transplanted on the 29th of the same month and the PRE herbicides applied on the 30th. Weed control was evaluated at 67 and 114 days after PRE application. The grass control was over 90% by trifluralin, bromacil and terbacil, around 80% by simazine and below 75% by the remaining herbicides. The broadleaves were controlled at a level of 90 to 100% by bromacil and terbacil and 80 to 85% by simazine. None of the herbicides affected the growth of sisal plants during the considered period of 600 days. At 550 days the area covered by weeds was evaluated. Terbacil controlled still 75 and 95% of the total quantity of weeds, at the lower and higher doyes, respectively, trifluralin controlled 60 to 70% and the remainder below 45%. For final evaluation at 600 days, crop stand, number of plants with sprouts, number of leaves per plant and crop condition were considered. The treatments with best weed control also showed the best scores for crop development, partly due to their selectivity to sisal.