the Symposium on Wheats for More Tropical Environments - cimmyt

280improved rice-rice-wheat because. in<strong>the</strong> past three years. <strong>the</strong> use ofimproved varieties and betteragronomic practices has steadilyincreased. The o<strong>the</strong>r improved patternshave lower production and net returns.There are two land categories in PumdiBhumdi. The rainfed lowlands have ahigh production potential where <strong>the</strong>cropping pattern is rice-wheat-maize.and a medium production potentialwhere <strong>the</strong> cropping pattern is ricemaize.Several years of testing haveresulted in <strong>the</strong> identification of a varietyof rice adapted to <strong>the</strong> hills. K39 is anearly-maturing variety with satisfactorygrain type. high grain yield. acceptablestraw characteristics; it is less damagedby hail. It fits into both <strong>the</strong> areas ofhigh and medium production-potential.Its yield ranges from 4.0 to 4.4 tlha in<strong>the</strong> rice-wheat-maize pattern and from3.6 to 4.4 tlha in <strong>the</strong> rice-wheat patternin <strong>the</strong> areas of high productionpotential. The maize variety Arun hasnow been adopted by farmers in bothhigh and medium production potentialareas. with yields up to 3.57 tlha. Yieldlevels of wheat (RR21) are low (1.9 t1ha)in both patterns. Hence. better varietiesof wheat are needed to fur<strong>the</strong>r increaseproduction and income.The rice-wheat-maize pattern undergood agronomic management wastested in 1982-83 in <strong>the</strong> highproduction potential areas. The annualproduction was 12.8% higher than <strong>the</strong>farmers' rice-wheat-maize pattern. but<strong>the</strong> net returns did not differ. Theresults of several tests led to farmeradoption of improved agronomicpractices and high-yielding varieties. In<strong>the</strong> medium production potential areas.four cropping patterns were tested. ricewheat.rice-maize. rice-broad beansmaizeand rice-oats. The highest netreturn was obtained from <strong>the</strong> rice-maizepattern (US$ 899); it was 25% higherthan <strong>the</strong> rice-wheat pattern.BangladeshWheat is a nontraditional crop inBangladesh. In <strong>the</strong> 1970s. a ten-foldincrease in wheat production wasachieved. It increased from a total of89.000 tons in 1973 to 1.1 million tonsin 1981. ApproXimately 500.000hectares are now under rice-wheatcropping systems. There is <strong>the</strong> potentialto expand to about 2 million hectares. ifbetter varieties are identified andirrigation prOVided. Wheat is generallygrown after transplanted Aman rice inrainfed and irrigated rice areas. Themost common cropping patternsinvolving wheat are rice-wheat and ricerice-wheat.On-farm cropping systems research inBangladesh is conducted on 16 sites byseven institutions under <strong>the</strong>coordination of <strong>the</strong> BangladeshAgricultural Research Council. Inseveral sites. <strong>the</strong> rice-wheat system isone of <strong>the</strong> patterns being studied. As inNepal. <strong>the</strong> farmers' existing croppingpattern is compared with alternative orimproved cropping patterns. ResultsinvolVing wheat from three sites arepresented in Table 3.The farmers in Hathanzari traditionallygrow only two rice crops. and leave <strong>the</strong>field fallow for 180 days after harvest.The team has introduced wheat as athird crop. coupled with an improvedvariety of rice. The total yield of <strong>the</strong> tworice crops under improved managementwas 7.5 tlha. 32% better than <strong>the</strong>farmers' practice (6). The net returns ofrice-rice-wheat was 59% better than <strong>the</strong>farmers' rice-rice cropping pattern(Table 3).In <strong>the</strong> rainfed areas of Trishal Thana.<strong>the</strong> Bangladesh Agricultural Universitytested rice-rice-wheat and jute-ricewheat.The predominant or existingcropping patterns are rice-rice and juterice.using local varieties; wheat wasintroduced as a new crop. The yields ofimproved rice and jute were muchhigher than <strong>the</strong> local varieties. and <strong>the</strong>wheat crop was excellent. Net return