| Popis: |
Weeds have a negative influence on several fruit tree characteristics, such as yield, making it difficult to management practices in orchards. Alternative weed management methods, aiming to reduce the use of herbicides, have become attractive since herbicides are costly and cause environmental degradation. The use of cultivars with greater competitive ability against weeds has attracted international attention. The objective of this work was to evaluate the floristic composition and growth of weeds under the canopies of irrigated custard apple tree progenies. Twenty halfsibling progenies around three years of age were evaluated in a random block design with five replicates and four plants per plot. A circle with a 0.5 m² area was established around the trunk of each plant. Floristic composition, fresh matter, and dry matter mass of the above-ground part of the weeds, were evaluated in this area. Root collar and canopy diameters, as well as leaf area of the progenies were also evaluated. Fifty-eight weed species were recorded. The five weed families with the most species were Leguminosae, Convolvulaceae, Euphorbiaceae, Malvaceae and Sterculiaceae, in decreasing order. The number of weed species per plot ranged from 6 to 18, but there was no difference between the mean percentages of different weeds under the canopies of the progenies. The lowest weed fresh and dry matter masses occurred in progenies JG1 and SM8, respectively. There were no differences between progenies with regard to root collar diameter and leaf area; however, one of the lowest weed dry matter yields was observed under the canopy of progeny FE4, which showed the largest canopy diameter.As plantas daninhas (PD) afetam várias características das fruteiras, inclusive o rendimento, e podem dificultar a execução de tratos culturais nos pomares. Existe interesse em métodos alternativos de manejo das PD, visando reduzir o uso de herbicidas, que são caros e causam degradação ambiental. Dentre esses métodos, a adoção de cultivares com maior habilidade competitiva com as PD tem despertado atenção internacional. O objetivo do trabalho foi avaliar a composição florística e o crescimento de PD sob a copa de progênies de pinheira irrigadas. Vinte progênies de meias-irmãs, com idade aproximada de três anos, foram avaliadas no delineamento de blocos ao acaso, com cinco repetições e quatro plantas por parcela. Ao redor do caule de cada planta estabeleceu-se um círculo com área de 0,5 m². Nessa área, foram avaliadas a composição e as massas das matérias fresca e seca da parte aérea das PD. Avaliaram-se também os diâmetros do colo e da copa e a área da folha das progênies. Ocorreram 58 espécies de PD. As famílias com maior número de espécies, em ordem decrescente, foram Leguminosae, Convolvulaceae, Euphorbiaceae, Malvaceae e Sterculiaceae. O número de espécies de PD/parcela variou de 6 a 18, porém não houve diferença entre a porcentagem média de diferentes PD sob a copa das progênies. As menores massas de matérias fresca e seca de PD ocorreram nas progênies JG1 e SM8, respectivamente. Não houve diferenças entre progênies quanto a diâmetro do colo e área foliar, mas sob a copa da progênie FE4, que apresentou o maior diâmetro da copa, observou-se um dos menores rendimentos de matéria seca de PD. |
