Effect of nitrogen levels and weed management methods on weed abundance and yield of upland rice (Oryza sativa L.)

Abstract

Weed infestation and inherent low soil fertility are among the major factors attributed to the low yield of rice in Nigeria. Field trials were therefore conducted to evaluate the effect of nitrogen application levels and weed control methods on growth and yield of upland rice (var. NERICA 2) at the Teaching and Research Farm of the Federal University of Agriculture, Abeokuta (07o 15?N, 03o 25?E) during 2015 and 2016 cropping seasons. Three nitrogen (N) levels (0, 60 and 90 kg/ha) were evaluated and they constituted the main plot treatments, while three weed control treatments, viz: pre-emergence application of Orizo Plus? (propanil plus 2, 4-D) at 2.0 kg a.i ha-1, Orizo Plus? at 2.0 kg a.i ha-1 followed by supplementary hoe weeding (SHW) at 6 weeks after sowing (WAS) and three hoe-weeding regimes at 3, 6 and 9 WAS, and a weedy check constituted the sub-plot treatments. All the treatments in different combinations were laid out in a randomized complete block design with a split-plot arrangement with three replicates. Results indicated a significant (p?0.05) increase in weed density and dry matter with an increase in N application level from 0 to 90 kg ha-1. Similarly, crop vigour and plant height increased significantly (p?0.05) with increasing N application levels up to 90 kg ha-1. However, 60 and 90 kg N ha-1 were at par in increasing the number of tillers, leaf area index and yield attributes of rice. All the weed control methods resulted in a significant (p?0.05) reduction in weed density and dry matter with subsequent increase in rice growth and yield than the weedy check. Pre-emergence application of Orizo Plus? followed by SHW at 6 WAS and three hoe-weeding regimes resulted in significantly (p?0.05) lower weed density and dry matter, and a higher number of tillers, panicle weight and grain yield than a sole application of Orizo Plus?. With Orizo Plus? followed by one SHW or three hoe-weeding regimes, increasing N application levels resulted in a significant (p?0.05) increase in grain yield of rice. However, with Orizo Plus? applied alone, increasing N application levels did not increase rice grain yield. These results suggest that Orizo Plus? at 2.0 kg a.iha-1 followed by one SHW at 6 WAS integrated with N application at 90 kg ha-1 is adequate to effectively control weeds and increase rice yield in the rainforest-savannah transition zone of Nigeria.

Complete chloroplast genome and comparison of herbicides toxicity on Aeschynomene indica (Leguminosae) in upland direct-seeding paddy field

“…From the perspective of crop protection, it is necessary to study reasonable measures to eliminate Indian jointvetch from paddy fields. The advantages of chemical methods for weed control in upland direct-seeding rice fields have been reported for decades in terms of higher yields and lower labor costs [ 30 – 32 ]. However, the chemical control of Indian jointvetch is currently very challenging [ 3 ].…”

“…Current weed control methods in upland direct-seeding rice fields mainly include cultural weed management practices and physical methods such as deep plowing, germination, mechanical weeding, and hand-pulling weeding, along with chemical methods using herbicides [ 28 – 30 ]. Chemical methods for weed control in upland direct-seeding rice fields have specific advantages of obtaining higher yields with relatively lower labor costs [ 30 – 32 ]. Aeschynomene weeds are often controlled using a combination of imazapyr and imazapic herbicides [ 3 ].…”

Challenges of weed management in rice for food security in Africa: A review

“…for the proper management of weeds, water and soil (Silva et al, 2007;Rodenburg and Johnson, 2009). The effect of timely fertiliser application (Adigun et al, 2017;Kolo et al, 2020), narrow row spacing (Kasim et al, 2017) and optimum seed rate (Ampong-Nyarko and De Datta, 1991;Johnson, 1996) to suppress weeds have been reported in rice systems in Africa. Apart from grain yield increase, Kasim et al (2017) reported that 14 cm row spacing was more effective in reducing weed density and biomass than 20 cm row spacing in upland rice.…”

“…Of all the factors attributed for the low yield of rice, weed competition is one of the most deleterious resulting in about 48 to 100% yield reduction (Adeyemi et al, 2017;Adigun et al, 2017;Kolo et al, 2020). On a global scale, 37% of the rice yield is considered to be lost to weeds (Oerke and Dehne, 2004).…”