the Symposium on Wheats for More Tropical Environments - cimmyt

52materials (F2 to FS generations) wereintroduced, and <strong>the</strong> yield potential insome materials was aceptable (Table 3).During this period, research was alsoconducted on planting date, plantdensity, fertilization, weed control andwater requirements. Some of <strong>the</strong> resultsare presented in Tables 4 and 5.Results showed that <strong>the</strong> dry seasonoffered better opportunities for growingwheat. Appropriate seeding rate wasfound to be from 140 to 160 kg/ha, and<strong>the</strong> optimum economic fertilizer dosage,80 and 40 kg/ha of nitrogen andphosphorus, respectively. Acceptableweed control was obtained with amixture of Fluorodifen (1.5 kg a.1.1ha)plus Linuron (0.5 kg a.1.1ha).Among <strong>the</strong> diseases, rusts were not aproblem dUring <strong>the</strong> dry season, exceptthat stem rust was observed in latetillers. For wet locations, Fusarium spp.and Erysiphe spp. were <strong>the</strong> mostimportant diseases, causing spike andgrain damage. In 1976, some spots ofdead plants, in different vegetativestages, were observed; <strong>the</strong> causal agentwas Sclerotium rolfsit. The diseasespread very qUickly from 1977 to 1979,killing SO, 60 and 85%, respectively, of<strong>the</strong> germplasm under evaluation.ConclusionsIn 1979, <strong>the</strong> National Cereal Programdecided to terminate research on wheatfor <strong>the</strong> coastal areas after considering<strong>the</strong> serious limitations for <strong>the</strong> growth ofwheat in that area. The most importantreasons for this were:• The low comparative economicreturn as compared to local crops;• The lack of irrigation systems, whichwould be imperative for growingwheat in dry areas of <strong>the</strong> Ecuadoriancoast;• The relatively low yield potential(4 Uha), compared to <strong>the</strong> potential for<strong>the</strong> highlands (6 Uha);• The cost of wheat production perhectare, which on <strong>the</strong> coast is twicethat of <strong>the</strong> highlands, and• The Sclerotium rolfsit problem, aswell as <strong>the</strong> potential insect, diseaseand weed competition problemsforeseen once farmers start plantingwheat.These problems would require major,costly research programs in breedingand agronomy.Table 2. Comparative wheat yields, wet anddry seasons, Portoviejo, Ecuador, 1964 to1969YearWet season(March-May)Yield (kg/ha)Dry season(June-8ept)1964196519661967196819691100120019501730270rft./230()!./2400380032003400A./ Planting date: April and May