关键词: 雨养农业, 降水保证率, 降水年型, 减产率, 适应性

Abstract:

【Objective】 In order to provide the important scientific reference for optimizing the layout of staple crops in Inner Mongolia, the adaptability of staple crops (maize, potato, oats, canola, oil and edible sunflower) was evaluated in four ecological regions of Inner Mongolia under different precipitation year types.【Method】Four typical sites in four ecological regions were selected. The validated APSIM model was used to quantify the potential yields, rainfed yields and yield gaps of six crops. Yield reduction rates of rainfed yields relative to potential yields under different precipitation year types were calculated to evaluate the adaptability of staple crops. Crop water production functions were conducted to analyze crop water sensitivity. 【Result】RMSE between simulated and observed vegetative growth period, reproductive growth period, dry yield was 10.1 d, 8.9 d, and 1 322.4 kg·hm^-2, respectively. NRMSE between observed and simulated vegetative growth period, reproductive growth period, and dry yield was 14.6%, 19.2%, and 22.6%, respectively. The validation results showed that APSIM could effectively simulate the growth, development, and yield of each crop in different regions. The potential dry yields of maize, potato, oats, canola, oil sunflower, and edible sunflower were 12 024±4 874, 7 315±806, 6 611±906, 2 424±326, 2 721±205, and 4 905±428 kg·hm^-2, respectively. The potential yields of oats and edible sunflower reached the maximum values in the north foot of Yinshan Mountains while potential yields of other four crops reached the maximum values in the Loess Plateau. The rainfed dry yields of maize, potato, oats, canola, oil sunflower, and edible sunflower were 3 056±2 902, 3 337±1 608, 2 974±1 677, 912±511, 869±618, and 1 508±984 kg·hm^-2, respectively. Average rainfed yields of the six crops increased from west to east and reached the maximum values in Da Hinggan Mountains. Yield gaps of maize, potato, oats, canola, oil sunflower, and edible sunflower were 8 968±5 844, 3 978±2 358, 3 637± 2 122, 1 512±832, 1 852±749, and 3 397±1 328 kg·hm^-2, respectively. Except maize and oats, the yield gaps of four crops decreased from west to east and reached the minimum values in Da Hinggan Mountains. Taking the yield reduction rate from potential to rainfed conditions as the drought index under the rainfed condition and considering the variation coefficients of rainfed yields, it was not suitable to plant crops in any years in the Loess Plateau. In the north foot of Yinshan Mountains, crops were not suitable for planting in dry years. Potato was suitable for planting in normal years, while potato and oats were suitable for planting in wet years. At the foothills of Yanshan hilly area, crops were not suitable for planting in dry years. Potato and oats were suitable for planting in normal years while six crops were all suitable for planting in wet years. In Da Hinggan Mountains, potato, oats, canola, and edible sunflower were suitable for planting in dry years, while six crops were all suitable for planting in normal and wet years. The linear correlations between the relative evapotranspiration and the relative yield of the six crops were all significant (P<0.01) with R² ranging from 0.84 to 0.99. The sensitivity of crop to water stress was in the order of oil sunflower, edible sunflower, maize, oats, canola, and potato.【Conclusion】This study revealed the adaptability of staple crops under different precipitation year types in the four ecological regions of Inner Mongolia. There was a large difference in water sensitivity of six crops. Under rainfed condition, potato were suitable for planting in normal and wet years in the north foot of Yinshan Mountains and the foothills of Yanshan hilly area, and in all year types in Da Hinggan Mountains. Oats were suitable for planting in wet years in the north foot of Yinshan Mountains, in normal and wet years in the foothills of Yanshan hilly area and in all year types in Da Hinggan Mountains. Canola and edible sunflower were suitable for planting only in wet years in the foothills of Yanshan hilly area and in all year types in Da Hinggan Mountains. Maize and oil sunflower were suitable for planting only in wet years in the foothills of Yanshan hilly area and in normal and wet years in Da Hinggan Mountains.

Key words: rainfed agriculture, guaranteed rate of precipitation, precipitation year type, yield reduction rate, adaptability