Effects of used plastic film disposal patterns on dry matter productionand water use efficiency of oil flax in arid areas

Field experiments were conducted to investigate how disposal patterns of used plastic films in field and mechanism of oil flax production enhance in arid areas. The study compared the influences of 6 used plastic film disposal patterns on oil flax soil water amount, leaf area, dry matter accumulation and distribution, water use efficiency and yield. The 6 patterns included field-kept film and no-tillage sowing the next year (T1); field-kept film, earth mulching and no-tillage sowing the next year (T2); field-kept film, straw mulching the current year and no-tillage sowing after straw clearing the next year (T3); field-kept film replaced with new plastic film and no-tillage sowing the next year (T4); film collection, land preparation, new plastic film mulching just after harvest and sowing the next year (T5); and collected just after crop harvest, land reparation and no-mulch sowing the next year (T6, control). The results showed that keeping used plastic films in fields till the next year had the same film mulch effect on soil moisture and temperature, thereby promoting photosynthetic area and favoring assimilation product accumulation. Soil moisture conservation effect under different disposal patterns of used films was strong before budding stage, ensuring the full and sound flax seedling growth. Leaf area response to the treatments had the same trend as soil water storage. Leaf areas in the five treatments were higher than in the control before budding stage. Treatment T4 was the best at momi fir pattern stage and budding stage, but T5 was the best at flowering stage. Accumulated amount of dry matter, amount and distribution proportion of dry matter, contribution of dry matter assimilation amount after anthesis to grain under T4 and T5 were higher than T6 (CK). And dry matter proportions in stem, spike axis and kernel husk also decreased. Also the values of these variables under T1, T2 and T3 were between those for T4 and T5. Yield of T1 to T5 treatments were significantly higher than T6, treatment T4 had the highest grain yield (1 509.52 kg·hm^-2) with T5, T1, T2, T3 and T6 yields of 1 370.77 kg·hm^-2,1 171.84 kg·hm ^-2,1 158.47 kg·hm^-2,1 011.36 kg·hm^-2 and 620.52 kg·hm^-2, respectively. The trend in water use efficiency was the same as that in yield, which increased respectively by 153.63% (T4), 129.82% (T5), 97.49% (T1), 85.71% (T2) and 64.41% (T3) over CK. Therefore the study recommended T4 as the most appropriate tillage practice in high-yield and water-saving oil flax production. However, optimal reuse pattern of used plastic film also needed considerations of local soil physical conditions and disposal method selection.