Abstract
A research was carried out to study phytosociology and to determine the periods of weed interference in the okra crop in organic cropping system. The experiment was laid out in a randomized complete block design with 20 treatments and four replications. The treatments were 10 periods of weed coexistence with the crop during 0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56, 0-63 and 0-74 days after crop emergence (DAE) and 10 periods weed free during 0-7, 0-14, 0-21, 0-28, 0-35, 0-42, 0-49, 0-56, 0-63 and 0-74 DAE. The weeds were evaluated by the number of individuals and accumulated dry biomass of each population in the treatments. The relative frequency, relative density, relative dominance and importance value index of each species were used to determine the effect the weeds. The most important weeds based on the Importance value index were Commelina benghalensis L., Cynodon dactylon (L.) Pers., Eleusine indica L., Phyllanthus niruri L. and Alternanthera tenella Colla. The period prior to interference and the total period of interference prevention were respectively of 12 and 36 days after emergence. The weed community caused yield losses of around 51%. In okra organic cropping system, weed control should be done early to boost okra plant growth in order to provide shade on the weeds to reduce the need for long control period. Key words: Abelmoschus esculentus (L.) Moench, competition, weed community.
Highlights
Okra [Abelmoschus esculentus (L.) Moench], is a well adapted species to tropical and subtropical climates. It is widely grown in Brazil, by smallholders (Purquerio et al, 2010) in conventional cropping systems, it can be grown in organic cropping systems as well, since it generally demands high amount of organic fertilizer which is essential for proper plant nutrition, fruit quality and yield increase with less or no use of synthetic fertilizers (Sediyama et al, 2009)
In the okra conventional cropping system, Bachega et al (2013) found 19 species arranged in 12 families with 63% of species belonging to the dicot group and 37% to the monocot group. These results show that the weed species diversity in the okra organic cropping system was higher when compared to the conventional cropping system, indicating that no soil disturbance, use of manure and favorable weather conditions contributed to greater weed community diversity
Santos et al (2010) found in okra conventional cropping system, values between 25 and 100 days after crop emergence (DAE) for the CPIP, covering 79 days of okra crop cycle. These results indicate that in an okra organic cropping system, weed control should be carried out early to boost okra plant growth to provide shading on the weeds, because the time needed for control was not extensive
Summary
Okra [Abelmoschus esculentus (L.) Moench], is a well adapted species to tropical and subtropical climates. It is widely grown in Brazil, by smallholders (Purquerio et al, 2010) in conventional cropping systems, it can be grown in organic cropping systems as well, since it generally demands high amount of organic fertilizer which is essential for proper plant nutrition, fruit quality and yield increase with less or no use of synthetic fertilizers (Sediyama et al, 2009). Premsekhar and Rajashree (2009) observed that the application of organic fertilizers resulted in various positive effects on okra growth and yield. A limiting factor in okra production in organic system is weed interference.
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