عنوان مقاله [English]
To study the effects weed competition periods on fruit yield and yield components of Okra and some of its morphological traits, a completely randomized design experiment with 12 treatment and 13 repetitions was carried out at the Research Fields of College of Agriculture of Birjand Branch, Islamic Azad University, in 2016. The plots consisted of the control (free of weeds until 4, 6, 8, 10 and 12 weeks after okras growth) and the treatments competing with the weeds within the same periods as mentioned above. Also, two separate plots were designed one for complete weed control during whole growth period and in the other weeds were allowed to compete with okra during the growth period, in order to compare the effects of weeds on okra. In the first group the plots were weeded during periods the mentioned above and in the other weeds were let to compete with okra. In the second group weeds competed with okra from the beginning of the growth period to 4, 6, 8, 10 and 12 weeks after germination. There after weed were controlled up to harvest time. The results showed that by increasing competition periods of weeds morphological traits of okra like plant height, main stem branche numbers, fresh fruit length and its diameter, as well as the number of fresh fruits per m-2, fresh fruit and dried fruit yields, biological yield and dried fruit harvest index per plant, dry weight of broad and narrow leaved weeds, and the percentage of dry fruit yield as compared to that of control treatment were significantly decreased. Based on 5 and 10 percent reduction in fruit yield, starting days of critical weed control period was determined to be 29 and 30 days after seed germination. Thus, it can be concluded that the critical weed period, in terms of okra yield in regard with the mentioned levels, was estimate to be 77 and 80 days after seedling emergence. Therefore, it is recommended that from the 29th to 80th day after seedling emergence of the okra, the field ought to be free of weed.
· Adeniyi, O.R., and A. Ayandiji. 2011. An agro-economic appraisal of the response of okra to leaf defoliation: growth and marketable yield. African Journal of Food, Agriculture, Nutrition and Development. 11(3): 4867-4879.
· Almarie, A.A. 2017. The critical period for weed competition in soybean Glycine max (L.) Merr. under Iraqi irrigated areas. Journal of Agricultural and Biological Science. 12(4): 128-132.
· Amador-Ramirez, M.D. 2002. Critical period of weed control in transplanted chilli pepper. Weed Research Oxford. 42(3): 203-209.
· Anwar, M.P., A.S. Juraimi, B. Samedani, A. puteh, and A. Man. 2012. Critical period of weed control in Aerobic Rice. The Scientific World Journal. 5: 1-10.
· Awodoyin, R.O., and O.S. Olubode. 2009. On field assessment of critical period of weed interference in okra [Abelmoschus esculentus (L.) Moench] field in Ibadan, a rain forest-Svanna transition eco-zone of Nigeria. Asian Journal of Food and Agro-Industry Production. Special Issue. 288-290.
· Azeem, A., Y. Wu, D. Xing, Q. Javed, and I. Ullah. 2017. Photosynthetic response of two okra cultivars under salt stress and re-watering. Journal of Plant Interactions. 12(1): 67–77.
· Blackshshaw, R.E., D. Lemerle, R. Mailer, and K.R. Young. 2002. Influence of wild radish on yield and quality of canola. Weed Science. 50: 344-349.
· Chaudhari, S., K.M. Jennings, D.W. Monks, D.L. Jordan, C.C. Gunter, S.J. Mc Gowen, and F.J. Louws. 2016. Critical period for weed control in grafted and nongrafted fresh market tomato. Weed Science. 64(3): 523- 530.
· Dada, O.A., and O.O. Fayinminnu. 2010. Period of weed control in okra [Abelmoschus esculentus (L.) Moench] as influenced by varying rates of cattle dung and weeding regimes. Notulae Botanicae Horti AgrobotaniciCluj-Napoca. 38(1):149-154.
· Gupta, O.P. 2006. Modern weed management. Agrobios Publ. India.
Iderawumi, A.M., and C.E. Friday. 2018. Characteristics effects of weed on growth performance and yield of maize (Zea Mays). Biomedical Journal of Scientific and Technical Research. 7(3): 1-4.
· Keramati, S., H. Pirdashti, M.A. Eslmaili, A. Abbasian, and M. Habibi. 2008. The critical period of weed contol in soybean (Glycin max L.) in north of Iran condition. Pakistan Journal of Biological Science. 11(3): 463-467.
· Knezevic, S.Z., S.P. Evans, E.E. Blankenship, R.C. Van Acker, and J.L. Lindquist. 2002. Critical period for weed control: the concept and data analysis. Weed Science. 50: 773–786.
· Lance, R.G., and M. Liebman. 2003. Alaboratory exercise for teaching critical period for weed control concepts. Weed Technology. 17: 403-411.
· Madandoust, M., and A. Ranjbar. 2017. Effects of solarization on critical period of weed control in sesame (Sesamum indicum L.). Agricultural Economics. 46(4): 272-278.
· Marttin, S.G., R.C. Van Acker, and L.F. Friesen. 2001. Critical period of weed control in spring canola. Weed Science. 49: 326-333.
· Mohammadi, G.R., and F. Amiri. 2011. Critical period or weed control in soybean (Glycine max) as influenced by starter fertilizer. Australian Journal of Crop Science. 5(11): 1350-1355.
· Monteiro, A., I. Henriques, and I. Moreira. 2011. Critical period for weed control in potatoes in the Huambo Province (Angola). Planta Daninnha, Vicosa-MG. 29(2): 351-326.
· Olabode, O.S., O.G. Adesina, and A.T. Ajibola. 2010. Seasonal effects on the critical period for weed removal and okra performance on Tithonia diversifolia (Helmsl) A. Gray infested field. Annals of Biological Research. 1(4): 76-72.
· Olasotan, F.O. 2001. Optimum population density for okra (Abelmoschus esculentus (L) Moench) in a mixture with cassava (Manihot esculentus) and its relevance to rainy season-based cropping system in south-western Nigeria. Journal of Agricultural Science. 136: 207-214.
· Orkwor, G.C.E. 1990. Studies on critical period of weed interfere in yam (Dioscorea rotundata poir) intercropped with maize (Zea mays L.) and okra (Abelmoschus esculentus L. Moency), sweet potato (Ipomoea batata L.) and the biology of the associated weeds. Ph.D Thesis, University of Nig, Nsukka, Nigeria. 262.
· Pacanoski, Z. 2014. Application time and herbicide rate effects on weeds in oilseed rape (Brassica napus var. Oleifera). Herbologia. 14(1): 33-45.
· Patel, S.M., A.U. Amin, and J.A. Patel. 2016. Effect of weed management practices on weed indices, yield and economics of cumin (Cuminum cyminum L.). International Journal of Seed Spices. 6(2): 78-83.
· Santos, B.M., W.M. Stall, S.M. Olson, S.E. Webb, and S.Z. Hang. 2010. Okra production in Florida. Horticultural Science Department. 729: 159-166.
· Seyyedi, S.M., P. Rezvani Moghadam, and M. Nassiri Mahallati. 2016. Weed competition periods affect grain yield and nutrient uptake of black seed (Nigella Sativa L.). Horticultural Plant Journal. 2(3): 172–180.
· Shaalan, A.M., K.A. Abou-zied, and M.K. El-nass. 2014. Productivity of sesame as influenced by weeds competition and determination of critical period of weed control. Alexandria Journal of Agricultural Research. 59(3):179-187.
· Steven, G.M., R.C. Van Acker, and F.F. Lyle. 2001. Critical period of weed control in spring canola. Weed Science. 49(3): 326-333.
· Swanton, C.J. and S.F. Weise. 1991. Integrated Weed Management in the Rational and Approach. Weed Technology. 5(3): 657-663.
· Tagour, R.M.H. 2015. Mathematical models for determination of the critical period of weed competition in sunflower (Helianthus annuus L.). Alexandria Journal of Agricultural Research. 60(3): 241-251.
· Thomaso, J.M., S.C. Weller, and F.M. Ashton. 2002. Weed science. Priciples, 4th ed. United States of America.
· Triphati, K.K., O.P. Govila, W. Ranjini, and A. Vibha. 2011. Biology of Abelmoschus esculentus L. (okra). Ministry of Environment and Forests Government of India and Department of Biotechnology Ministry of Science and Technology Government of India.22.
· Uremis, I., A. Uludag, A.C. Ulger, and B. Cakir. 2009. Determination of critical period for weed control in the second crop corn under Mediterranean conditions. African Journal of Biotechnology. 8(18): 4475-4480.
Weaver, S.E., M.J. Kropff, and R.W. Groenevled. 1992. Use of ecophysiological models for crop-weed interference: the critical period of weed interference. Weed Science. 40: 302-307.