奈曼地区灌溉麦田蒸散量及作物系数的确定

利用大型蒸渗仪测定了奈曼地区春小麦(Triticum aestivum L.)全生育期的蒸散量，并引用FAO Penman-Monteith等5种方法计算了相应时期的参考作物蒸散量，比较了FAO Penman-Monteith公式与其它4种方法间的关系，最后运用作物蒸散量和参考作物蒸散量计算了春小麦的作物系数．结果表明，春小麦苗期每周日平均蒸散量小于3mm·d^-1，随着叶面积系数增大，日平均蒸散量达到最大值6．49mm·d^-1(抽穗开花期)，最终下降至1．94mm·d^-1(灌浆成熟期)；根据试验年份的降雨分布情况，该地区的自然降水不能满足春小麦对水分需求，小麦苗期、拔节期和抽穗开花期水分亏缺比较严重，是田间水分管理的关键时期；与FAO Penman-Monteith公式的计算结果相比较，用Penman公式和FAO-24 Blaney-Criddle公式估算奈曼地区参考作物蒸散量误差较小；奈曼地区春小麦苗期、营养期、生殖期、成熟期4个生长阶段的作物系数分别为0．45、0．90、1．1l和0．52，其中成熟期的作物系数值与FAO-24给出的小麦作物系数值差异较大．

Measurement of evapo-transpiration and crop coefficient of irrigated spring wheat in Naiman sandy cropland

Lysimeter experiments were conducted with spring wheat during cropping seasons to measure the crop evapo-transpiration at Naiman region, and reference evapo-transpiration during these seasons was calculated with FAO Penman-Monteith and other four methods. The relationship between FAO Penman-Monteith and other reference evapo-transpiration methods was established, and the crop coefficients for spring wheat based on crop evapo-transpiration and reference evapo-transpiration were also developed. The results showed that the average weekly ETc of spring wheat was less than 3 mm.d-1 in the seedling phase. With the LAI increased, the average weekly ETc reached the peak of 6.49 mm.d-1 (at heading phase), and declined to 1.94 mm.d-1 during maturity phase. The local precipitation in the year of experiment did not satisfy the water demand for wheat production, and seedling, jointing, heading phases of spring wheat were the key phases in the course of water management. The differences in ETr estimates between FAO Penman-Monteith and Penman and FAO Blaney-Criddle methods were obviously lower than those between FAO Penman-Monteith and Makkink and Priestley-Taylor methods. The calculated values of crop coefficient for spring wheat at the four crop growth phases (initial, crop development, reproductive and maturity) were 0.45, 0.90, 1.11 and 0.52, respectively. The coefficient at maturity stage differed considerably from those suggested by FAO-24.