Effect of mixed cropping and plant extracts on the growth, yield and pest control of jute (Corchorus olitorius L.)

This study investigated the effect of plant extracts (Azadirachta indica and Piper guineense) on the growth and yield of jute (Corchorus olitorius L.) (Cor) under sole and mixed cropping with Amaranthus hybridus (Ama) and Celosia argentea (Cel). The highest percentage increase in plant height, number of leaves, number of branches and stem girth (130.6, 865.0, 220.4 and 114.0%, respectively) was found in untreated Cor + Cel, cypermethrin treated Cor + Ama, cypermethrin treated Cor and A. indica extract treated Cor + Ama, respectively. The highest percentage increase in shoot weight (71.0%), marketable yield (53.9%) and total biomass (51.5%) was in A. indica treated C. olitorius. Extract treatment had no effect on the number of branches at four, five and seven weeks after planting (WAP) in Cor + Ama + Cel; four, five and six WAP in Cor + Cel; four and six WAP in Cor + Ama; as well as four and five WAP in Cor. The highest percentage increase in leaf fresh weight was obtained in cypermethrin treated Cor (53.3%) and Cor + Ama + Cel (52.2%), while the smallest increase was in P. guineense treated Cor (1.1%) and Cor + Ama (2.5%). The activity of A. indica was independent of time of application while P. guineense was not. Among the extract treated groups, the highest percentage increase in shoot weight (71.0%), marketable yield (53.9%) and total biomass (51.5%) was in A. indica treated Cor. The activity of the extracts against insect pests of sole cropped Cor increased significantly (p < 0.05) with increasing extract concentration. The highest efficiency with the use of P. guineense was 250 g dm-3 at four, five and six WAP (94.0, 92.7 and 90.3%, respectively) and 200 mg dm-3 at seven WAP (81.7%). In the case of A. indica extract, the highest efficiency was found with the use of 200 g dm-3 at four, six and seven WAP (92.7, 85.3 and 100%, respectively). A. indica extract (250 g dm-3) treatment gave the highest efficiency at five WAP (100%).