Responses of grain yield formation and water use characteristic of maize to plastic film mulching pattern and row spacing in oasis irrigation area in Northwest China

Full plastic film mulching is widely used in maize production in the Arid Oasis Irrigation area of Northwest China. The problem of residual plastic film pollution is of great concern, therefore it is important to study the cultivation techniques of the area in order to reduce pollution by plastic film. The effects of different film mulching patterns (full-film, half-film mulching) coupled with different row spacing (50 cm uniform row spacing and 40 cm + 80 cm paired row spacing) were used to test the yield, water consumption, water consumption structure, and water use efficiency of maize at the Shiyang River Basin in Hexi, Gansu. The results showed that high grain yield was obtained from the paired row spacing of full-film or half-film mulching conditions, which reached 14 712.7 and 14 155.2 kg·hm^-2, and they were 13.2% and 8.9% higher than that of the half-film mulching, respectively (P < 0.05). However, these were not significantly different from the uniform row spacing of full-film. This was due to the significant increase in spike number and the double-ear rate by planting in paired row spacing. Under the condition of full film mulching, the peak value of the leaf area index (LAI) was obtained by paired row space planting, with the average LAI of the maize during the whole growth period being significantly higher than that of half-film mulched treatment. The amount of evaporation at the early growth stage of maize decreased significantly under full-film mulching than under half-film mulching. The total amount of evaporation under half-film mulching with uniform and paired row spacing were 177.2 and 189.0 mm, respectively. And these were 14.3% and 21.9% respectively, significantly higher than that of full-film mulching with uniform row spacing. The water use efficiency of maize was 19.3 kg·mm^-1·hm^-2 under the conditions of half-film with paired row spacing, which was not significantly different from that of the full-film mulching. These results indicate that half-film mulching with paired row spacing instead of full-film mulching with uniform or paired row spacing will not lead to a decrease in the grain yield and water use efficiency of maize in the Arid Oasis Irrigation area of Northwest China.