the Symposium on Wheats for More Tropical Environments - cimmyt

278grown in rainfed upland or lowland riceareas where <strong>the</strong>re is enough rainfallduring <strong>the</strong> cooler season.Rice-Wheat Cropping SystemsMajor collaborative research in <strong>the</strong>Asian Rice Farming Systems Networkis in rice-wheat cropping; IRRI andCIMMYT are collaborating with 13countries in Asia. Nepal. Bangladesh.Thailand. Philippines. Sri Lanka.Bhutan. Pakistan. Malaysia. Indonesia.China. Taiwan. Burma and Korea. Theobjectives of <strong>the</strong> collaboration are to:• Identify rice-wheat cropping systemstechnology that is suitable for smallscalefarmers;• Identify better combinations of riceand wheat varieties;• Encourage rice and wheat scientiststo work toge<strong>the</strong>r and identifycomponent technologies that willincrease <strong>the</strong> production of rice-wheatsystems, and• Promote collaborative research in <strong>the</strong>network on o<strong>the</strong>r problems commonto <strong>the</strong> region.The fIrst two projects in thiscollaboration are cropping-patterntesting in six countries. Nepal. China.Taiwan. Bangladesh. Korea and SriLanka. and <strong>the</strong> International Rice­Wheat Integrated Trials (lRWIT) in all13 countries.Cropping-pattern trials are conductedon farmers' fields to compare rice-wheatsystems with o<strong>the</strong>r cropping systems.IRWIT. on <strong>the</strong> o<strong>the</strong>r hand, is a varietalevaluation trial of rice (from IRRI) andwheat (from CIMMYT) at <strong>the</strong> time <strong>the</strong>crop is grown within <strong>the</strong> system. IRRIproVides six varieties of rice, and <strong>the</strong>national programs are requested toinclude six varieties from <strong>the</strong>ir breedingprograms. For <strong>the</strong> wheat trials. CIMMYTprOVides fIve entries and nationalprograms five entries. There are two setsof trials for each crop for rice. a set ofearly-maturing rice for temperate andsubtropical countries and a set of earlyand medium-maturing rice varieties fortropical countries. For wheat. <strong>the</strong>re is aset of early-maturing wheat varieties foroptimum planting time (November 15 ±10 days) and a set of early-maturingvarieties for late planting(December 15 ±. 10 days).Rice-Wheat in South AsiaNepalRice-wheat rotation takes place onapprOXimately 480,000 hectares. and<strong>the</strong>re is potential for doubling <strong>the</strong> area.especially in <strong>the</strong> Tarai. Wheat is rotatedwith rice in both irrigated and rainfedareas. In <strong>the</strong> hills. rice-wheat and ricewheat-comare <strong>the</strong> common croppingpatterns while, in <strong>the</strong> Tarai rice-wheatand rice-rice-wheat are common. Insome areas. mixed cropping of wheatand mustard after rice is practiced.There are seven cropping systems sitesin Nepal. Of <strong>the</strong>se. three are involved in<strong>the</strong> network collaboration on croppingpatterntesting. Pumdi Bhumdi in <strong>the</strong>hills. Ratna Nagar in <strong>the</strong> inner Taraiand Bhairawa Tubewel) in <strong>the</strong> Tarai. InRatna Nagar. several cropping patternshave been tested on both irrigated andrainfed lowlands. Rice-wheat-mungbeanand rice-wheat-maize have given higherproduction and net returns ascompared to <strong>the</strong> farmers' practice ofrice-wheat (Table 1). The wheatvarieties Lumbini and UP262 haveyielded 65 to 91% more than <strong>the</strong>farmers' RR21; rice yield from varietiesLaxmi and Malaka Janaki was up to63% higher than <strong>the</strong> farmers' Masulivariety. On rainfed lowlands. ricemaize.with improved management.and rice-wheat patterns showed higherproduction and net returns ascompared with <strong>the</strong> local farmers' ricemaizepractice.In <strong>the</strong> Bhairawa Tubewell. 17 croppingpatterns were tested. Rice-maize-maizeshowed higher production and netreturns than did rice-wheat-rice(Table 2). The farmers' practice of ricerice-wheatis comparable to <strong>the</strong>