Control of weedy rice in direct-seeded rice using the clearfield production system in Malaysia.

Weedy rice (Oryza sativa complex) is a serious threat to directseeded culture in Malaysia because of its taxonomic and physiological similarities to cultivated rice. This weedy rice problem was first observed in 1988 but later became widespread and prevalent in rice cultivation in the 2000’s. Farmers have considered weedy rice as of significant importance and a serious threat since no selective herbicide was available for controlling it prior to the advent of an imidazolinone tolerant variety (IMI-TR). The development of local IMI-TR rice, a collaborative project between MARDI and BASF (Malaysia) Sdn Bhd, started in 2003 at MARDI Station in Penang. IMI-TR Line No. 1770 from USA was crossed with a popular local rice cultivar MR 220 using conventional breeding techniques. The goal of the project is to offer farmers an effective and farmer friendly solution to the weedy rice problem with minimal changes to their normal practices. Two locally developed IMI-TR varieties namely MR 220CL1 and MR 220CL2 together with the technique known as Clearfield Production System (CPS) were officially launched on the 8 th July 2010 in FELCRA Seberang Perak rice granary. This CPS for rice was the first launch in Malaysia as well as in the Asia Pacific Region. This system is justified by the need to offer an innovative alternative method to manage weedy rice in wet-seeding culture. The CPS package for rice consists of three main components namely Clearfield certified seeds, OnDuty herbicide (imazapic/imazapyr) and the Stewardship Guide. The seeds are supplied in standard 20 kg bags while the OnDuty herbicide is packed in a box of 4 sachets of 31 g each. The seed rate per ha is 7 bags (140 kg/ha) which is the normal seed rate used by farmers. The seeds and OnDuty herbicide are sold together as a package to ensure that; a) both seeds and herbicides are available together at all times, b) OnDuty herbicide and seeds are applied at the correct rate, and c) the correct variety together with the correct herbicide are used. To ensure successful crop establishment and attainment of high yield of Clearfield rice varieties, standard good agricultural practices have to be implemented and followed from sowing to harvesting. All these practices are basically similar to practices currently adopted by farmers in Malaysia.