caa a22 4500 606219021 CHVBK 20210128101116.0 cr unu---uuuuu 210128e20150601xx s 000 0 eng 10.1007/s11104-015-2383-y doi (NATIONALLICENCE)springer-10.1007/s11104-015-2383-y Barnyard grass ( Echinochloa crus - galli (L.) P.Beauv) is less competitive on rice ( Oryza sativa L.) when phosphorus (P) is applied to deeper layers in P-deficient and moisture-limited soils [Elektronische Daten] [L. Weerarathne, Lalith Suriyagoda, B. Marambe] Background and aims: Barnyard grass (Echinochloa crus-galli (L.) P.Beauv) is a major C4 weed in rice fields. We aimed to explore a management strategy to reduce its competition with rice (Oryza sativa L.) (C3) in low-phosphorus (P) soil with varying soil moisture availability. Therefore, we investigated the effect of P placement at different depths. Methods: The main experiment was conducted in pots (15cm diameter, 70cm height) filled with P-deficient soil as a replacement series with different plant combinations (rice and barnyard grass monocultures; four plants per pot, and a mixture of rice and barnyard grass; two plants of each species per pot) with two P placement depths (0-5 and 15-20cm from the soil surface) and three moisture treatments (continuous flooding - CF, alternate wetting and drying - AWD, and top soil drying - TSD from flowering). The pots were maintained until crop maturity. A rhizobox experiment supplemented the main experiment to study the root system plasticity during the initial growth stages (i.e., after 14 and 28days of growth). Key results: Placement of P in a deeper soil layer (15-20cm) reduced the growth and P uptake of barnyard grass by over 70 and 80%, respectively, irrespective of the plant combination, and moisture treatments, while such reductions were not observed in rice. Reduced growth and P uptake of barnyard grass were associated with the arrested root elongation even from the very early growth stages failing to search for P applied to 15-20cm soil layer. In contrast, root elongation of rice increased from early growth stages when P was applied at 15-20cm soil depth and reached the P-supplied soil layer to ensure P uptake. Average root diameter decreased by 12%, and the percentage fine root production (i.e., < 0.4mm diameter) increased by 8% when P was applied at 15-20cm deep compared with those at 0-5cm depth. Conclusions: Phosphorous placement at 15-20cm soil depth reduced the competitive ability of barnyard grass over rice in P-deficient soils, irrespective of the soil moisture management method. Springer International Publishing Switzerland, 2015 C3 nationallicence C4 nationallicence Competition nationallicence Growth nationallicence Nutrient-poor soil nationallicence Phosphorus nationallicence Root plasticity nationallicence Weerarathne L. Faculty of Agriculture, University of Peradeniya, 20400, Peradeniya, Sri Lanka aut Suriyagoda Lalith Faculty of Agriculture, University of Peradeniya, 20400, Peradeniya, Sri Lanka aut Marambe B. Faculty of Agriculture, University of Peradeniya, 20400, Peradeniya, Sri Lanka aut Plant and Soil Springer International Publishing 391/1-2(2015-06-01), 1-17 0032-079X 391:1-2<1 2015 391 11104 https://doi.org/10.1007/s11104-015-2383-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11104-015-2383-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Weerarathne L. Faculty of Agriculture, University of Peradeniya, 20400, Peradeniya, Sri Lanka aut NATIONALLICENCE 700 1- Suriyagoda Lalith Faculty of Agriculture, University of Peradeniya, 20400, Peradeniya, Sri Lanka aut NATIONALLICENCE 700 1- Marambe B. Faculty of Agriculture, University of Peradeniya, 20400, Peradeniya, Sri Lanka aut NATIONALLICENCE 773 0- Plant and Soil Springer International Publishing 391/1-2(2015-06-01), 1-17 0032-079X 391:1-2<1 2015 391 11104