My introductory orientations: A) Dry, direct-seeded rice is probably most seriously affected by weeds (in Tanzania "Echinocloa spp. " was most troublesome); still: the agro-economics of that prod.system is relevant and weed-research of utmost important. B) Sulfur, copper and zinc have some important fungus-disease-control-features, keep an eye on that interrelation. C) Pre-germinated rice seed can compete with weed much better; I suggest to include that parameter. D) In the probably humid, heavy-soil prone rice-areas any viable, confirmed info on easy weed-suppression ---by whatever means ---  will be highly wellcome; although the same conditions will trigger a massive weed-emergence; E) Keep an eye on the option of intermittend soil-preparation with enough days for weed-emergence in between. F) The impact of weeds during early rice-development can drastically reduce the numer of tillers/plant and # of grains-per-panicle, differentiated on the vegetation-point already in a 4-week-old plant.

Thanks Dr Bernhard. 

Thanks