WATER USE EFFICIENCY, GROWTH AND YIELD OF WHEAT CULTIVATED UNDER COMPETITION WITH Setaria

Water use efficiency, growth and yield of wheat cultivated under ... doi: 10.1590/S0100-83582015000400006 679 WATER USE EFFICIENCY, GROWTH AND YIELD OF WHEAT CULTIVATED UNDER COMPETITION WITH Setaria1 Eficiência do Uso da Água, Crescimento e Rendimento do Trigo Cultivado em Competição com Setaria IHSAN, M.Z.2, EL-NAKHLAWY, F.S.2, and ISMAIL, S.M.2 ABSTRACT - Understanding the critical period of weed competition is indispensable in the development of an effective weed management program in field crops. Current experiment was planned to evaluate the critical growth period of Setaria and level of yield losses associated with delay in weeding in rain-fed drip irrigated wheat production system of Saudi Arabia. Field experiment was conducted to evaluate the effect of weeding interval (07-21, 14-28, 21-35, 28-42 and 35-49 days after sowing) and drought stress (75% and 50% of field capacity) on Setaria growth, wheat yield and water use efficiency. Season long weedy check and wellwatered (100% FC) plots were also maintained for comparison. Weeding interval and drought stress significantly (p ≤ 0.05) affected the growth and yield of Setaria and wheat. Drought stress from 75% to 50% FC resulted in reductions of 29-40% in Setaria height, 14-27% in Setaria density and 11-26% in Setaria dry biomass. All weeding intervals except 35-49 DAS significantly suppressed Setaria growth as compared with control. Delay in weeding increased weed-crop competition interval and reduced wheat yield and yield contributors. Therefore, the lowest yield of 1836 kg ha-1 was attained for weeding interval of 35-49 DAS at 50% FC. Water use efficiency and harvest index increased with decreasing FC levels but reduced with delay in weeding. Correlation analysis predicted negative association of Setaria density with wheat yield and yield contributors and the highest negative association was for harvest index (-0.913) and water use efficiency (-0.614). Early management of Setaria is imperative for successful wheat production otherwise yield losses are beyond economical limits. Keywords: weed control, competition interval, Setaria viridis, field capacity, arid land. RESUMO - Compreender o período crítico de concorrência entre plantas daninhas é indispensável para o desenvolvimento de um programa eficaz de controle delas nas plantações. Este experimento teve como objetivo avaliar o período crítico de crescimento da Setaria e o nível de perdas de rendimento, associado à demora da capina das plantas daninhas, em um sistema de produção de trigo com irrigação por gotejamento de chuva na Arábia Saudita. O experimento em campo foi conduzido para avaliar o efeito do intervalo de capina das plantas daninhas (07-21, 14-28, 21-35, 28-42 e 35-49 dias após a semeadura) e do estresse hídrico (75 e 50% da capacidade de campo) sobre o crescimento da Setaria, o rendimento do trigo e a eficiência do uso da água. Os cultivos bem irrigados (100% de CC) e submetidos à verificação de plantas daninhas ao longo de toda a estação foram mantidos para comparação. O intervalo de capina das plantas daninhas e o estresse hídrico afetaram, de forma significativa (p ≤ 0,05), o crescimento e o rendimento da Setaria e do trigo. O estresse hídrico de 75 a 50% de CC causou reduções de 29 a 40% na altura da Setaria, 14 a 27% em sua densidade e 11 a 26% em sua biomassa seca. Todos os intervalos de capina, exceto o de 35 a 49 DAS, suprimiram significativamente o crescimento da Setaria, em comparação à testemunha. O atraso da capina elevou o intervalo de concorrência com plantas daninhas e reduziu o rendimento da produção do trigo e colaboradores do rendimento. Portanto, o menor rendimento (1.836 kg ha-1) foi obtido no intervalo de capina de 35 a 49 DAS em 50% de CC. A eficiência do uso da água e o índice de colheita 1 Recebido para publicação em 27.6.2015 e aprovado em 17.7.2015. Department of Arid Land Agriculture, Faculty of Meteorology, Environment & Arid Land Agriculture, King Abdulaziz University P.O. Box 80208, Jeddah: 21589, Saudi Arabia, <>. 2 Planta Daninha, Viçosa-MG, v. 33, n. 4, p. 679-687, 2015 680 IHSAN, M.Z. et al. elevaram-se com a redução dos níveis de CC, porém reduziram com o atraso da capina das plantas daninhas. A análise de correlação previu associação negativa da densidade da Setaria com o rendimento do trigo e colaboradores do rendimento, e a maior associação negativa foi do índice de colheita (-0,913) e eficiência do uso da água (-0,614). O manejo precoce da Setaria é essencial para o sucesso de rendimento do trigo. Se não houver o manejo precoce, as perdas de rendimento podem exceder os limites econômicos. Palavras-chave: controle de plantas daninhas, intervalo de concorrência, Setaria viridis, capacidade de campo, terra árida. INTRODUCTION Wheat (Triticum aestivum) is a prominent cereal crop and staple food for one third of global inhabitants (FAO, 2015). It is the most consumed grain cereal in Saudi Arabia with per capita consumption of 88 kg per year. In 2014-15, wheat was cultivated on an area of 83 thousand hectare (-17% reduction in area) with total yield of 425 thousand MT (-29% reduction in yield) (Mousa, 2014). Saudi wheat production continues its drastic decline, as the government enforces its policy to phase-out wheat cultivation subsidy and lack of farmer’s knowledge and expertise in crop management and weed control. The increasing demand and decreasing production is alarming, as demand continues to increase at a rate of 3.2% per annum. Moreover, fresh water availability is the major limitation for wheat production in the Peninsula. Arid features of this region bring multiple abiotic stresses, such as drought, salinity, heat, low soil fertility and organic matter (Oliveira et al., 2013). Along with various abiotic stresses, weeds are the major biotic constraint to wheat production accounting up to 48% yield losses (Oerke & Dehne, 2004). Weeds interfere with natural growth of the crop by competing for natural resources such as water, space, light, nutrient and air (Khaliq et al., 2013; Mahmood et al., 2015). Wheat yield losses are directly related to density, species, time of emergence, and weed-crop competition interval (Hussain et al., 2015). A strong direct relationship exists between competition duration and pressure on crop yield loss (Fahad et al., 2014). Green foxtail (Setaria viridis) is a C4 summer annual grassy weed with decumbent stem and graminoid growth habit (Rao et al., 1987; Jiang et al., 2013). Its stem can grow Planta Daninha, Viçosa-MG, v. 33, n. 4, p. 679-687, 2015 up to two meters in length, bearing dense inflorescence, compact spike with up to 20 centimeters length. Spikelets are subdivided into three stiff bristles and fertile lemmas are finally cross wrinkled (Brutnell et al., 2010). It has fibrous root system and reproduces by seed. Worldwide distribution of Setaria is observed, as wide range of habitat (cropland, fallow, pasture, barren uncultivated land, parks and vacant lots (...truncated)