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Cultural Technics for High Yielding CornProduction in Southern Provinces of VietnamVo Dinh LongAgricultural Training and Technology Transfer CentreInstitute ofAgricultural Science ofSouth VietnamAbstractCompared with 1992, com production in the southern part of Vietnam doubled in 1995, withcom hybrids occupying about 30% of the total area. Dongnai province has the biggest corn plantedarea under production and the highest yield (6.6 tonslha) of the country. For intensive comproduction, we should pay a special attention to 4 important factors by order of priority. First:variety; second: hard work; third: fertilizers and fourth: water.First: variety. Com variety having high yield potential, good grain quality, adapted to localconditions, resistant to lodging and to major diseases and insects, is the most important factor forobtaining high yield and high economic efficiency. Since 1992, high yielding tropical corn hybridshave been introduced or developed in the country such as DK 888, DK 999, LVN 10, Cargill 919,Pacific 60, Uniseed 89, Pioneer 3011, etc. Farmers produce an average 6 to 9 tons of dry corn grainsper hectare.Second: hard working. Hard working consists mainly of:- keeping an appropriate plant density at harvest- keeping the crop free of insects, diseases and weedsFor full season maturing hybrids such as DK 888 and LVN 10, the suitable plant density is50,000 plantslhectare. For intermediate maturing hybrids such as DK 999, Cargill 919, theappr priate plants density is 53,000 plantslha. However, at harvest the plant density often is too lowdue to insects, drought, waterlogging occurrence etc... So we recommend farmers to sow in small potsan amount of seeds for transplanting young seeding when it is needed.The most effective method to prevent corn stem borer is using Furadan 3G or Basudin lOGgranules by putting in the plant whorl. The first application takes place about 15 to 25 days aftersowing when insects appear on the leaves, and the second application is conducted 15 days later.Third: fertilizers. The optimum fertilizer rates for corn hybrids are:Nitrogen150-200 kglhaPhosphorus 60-90Potassium 30-60so we recommend for lOOOm2 of land:DAP (18-46% N-P205)Urea (46% n)Potassium chloride: (60% K20)15-20 kg25-35 kg5-lOkg- Basic application: total amount of DAP.- First side dressing (15 DAS): 1/3 urea + 1/3 Kcl- Second side dressing (25-30 DAS): 1/3 urea + 1/3 Kcl- Third side dressing (40-45 DAS): U3 urea + 1/3 KclFourth: water. Corn needs 349 kg of water to produce I kg of dry matter or 6000t of water toproduce 16t of dry matter (8 tons of grains + 8 tons of stalks). The most critical stage for corn is from2 weeks before silking to 2 weeks after silking. At this stage corn crop needs the biggest amount ofwater. If drought occurs at this period, grain yield can be seriously affected.