the Symposium on Wheats for More Tropical Environments - cimmyt

42Wheat Production in <strong>the</strong>Subtropical Areas of Santa Cruz, BoliviaC. Quintana, Centro de Investigaci6n Agricola Tropical, Santa Cruz,BoliviaBolivia needs 400,000 tons of wheat peryear to meet its total domestic needs.Unfortunately, present wheatproduction is not sufficient to satisfythis need. The subtropical areas of <strong>the</strong>country, such as <strong>the</strong> plains of SantaCruz province, offer a possible solutionin terms of prospects for wheatproduction expansion. This report willfocus mainly on <strong>the</strong>se subtropical areasof Santa Cruz.Wheat ProductionThe wheat area in nor<strong>the</strong>rn Santa Cruzis 10,000 hectares, but estimates forpotential wheat area in <strong>the</strong> region is160,000 hectares. In general, wheatcultivation is under rainfed conditions,with limited area under irrigation. Themain factors limiting production are:• Lack of aVailability of seed ofcommercial varieties• Lack of suitable technology forfarmers• Lack of moisture• Presence of diseases• Marketing, e.g., pricing restraints• Lack of credit for farmers• Agronomic problems such as weedsand low soil fertilityCharacteristics of <strong>the</strong>Subtropical ZoneRainfallFigure 1 shows <strong>the</strong> rainfall patterndUring <strong>the</strong> normal wheat cycle. It alsodemonstrates <strong>the</strong> problems duringplanting (May and June) and harvesting(September), due to excessive amountsof rainfall dUring those periods. Themean precipitation of <strong>the</strong> growing cycleover a 20-year period is 260 mm.Relative humidityData in Figure 2 give <strong>the</strong> 20-yearaverage relative humidity during <strong>the</strong>growing season. It ranges from 53 to73%, which favors diseasedevelopment.TemperatureFigure 3 illustrates <strong>the</strong> temperaturesdUring <strong>the</strong> growing season. based on aMay June July August SeptemberFigure 1. Rainfall during <strong>the</strong> wheat-growing season. nor<strong>the</strong>rn Santa Cruz,Bolivia (2o-year average)