图1. 黄土高原不同处理玉米的籽粒产量
FM,全膜覆盖;CK_FM,全膜覆盖对照,不覆膜;RM,半膜覆盖;CK_RM,半膜覆盖对照,不覆膜;FM_A（全膜覆盖）、RM_A（半膜覆盖）表示收集的文献中同时包含全膜覆盖和半膜覆盖。图中,最上方和最下方的线段分别表示数据的最大值和最小值,其中箱图的上方和下方的线段分别表示数据中25%和75%的数值,箱图中间的粗线段表示数据的中位数,箱图里面的方块表示数据中的平均数,最上方和最下方的叉号分别代表所有数据中的99%和1%的值。不同的小写字母表示处理与对照差异显著（P<0.05）;相同的大写字母表示全膜覆盖与半膜覆盖差异不显著（P>0.05）。下同

Fig. 1. Maize grain yield under plastic film mulching in the Loess Plateau
FM, 100% film mulching; CK_FM, control without film mulching relative to FM; RM, 50% film mulching; CK_RM control without film mulching relative to RM; FM_A (100% film mulching) and RMA (50% film mulching) represent collected literature includes both FM and RM treatments. The upper and lower limits of each box represent the 25% and 75% percentiles parameters’ values. The horizontal line in the center of the box indicates the median. The open circle indicates mean values, and short line indicate the max. and min. values, the cross indicate the 99% and 1% values. Different lower case letters mean significant difference between film mulching and its corresponding CK tested by t-test (P<0.05); Same capital letters mean insignificant difference between FM and RM tested by t-test (P>0.05). The same as below