PBAT/PLA全生物降解地膜的降解性能及对石河子垦区棉花生长的影响

为探讨PBAT/PLA全生物降解地膜在新疆棉花上的应用效果，以PE地膜为对照，在新疆石河子垦区开展PBAT/PLA全生物降解地膜应用试验，系统分析了PBAT/PLA地膜的降解性能及其对土壤温湿度、棉花长势和产量的影响。结果表明：PBAT/PLA地膜降解较快，在覆膜43 d即进入诱导期；红外、X射线衍射、扫描电镜等测试也表征出PBAT/PLA地膜田间降解后分子链、晶体结构和微观形貌等发生的一系列变化；在棉花生育前期，PBAT/PLA地膜膜面保持完整，增温保墒效果良好，两组出苗率一致；但随着PBAT/PLA地膜逐渐裂解，其应用效果开始下降，棉花进入盛蕾期后，PBAT/PLA地膜覆盖下土壤温度和含水率比PE地膜覆盖分别低0.30～1.15℃和2.31～3.46个百分点，最终导致PBAT/PLA地膜组的株高和茎粗较PE地膜组分别降低22.08%和12.82%，籽棉减产20.24%。因此，PBAT/PLA全生物降解地膜还需从材料分子链结构层面进行配方改良、推迟降解诱导期、提高棉田覆盖应用潜力，使其能更好在新疆棉花生产中进行试用推广。

Degradation performance of PBAT/PLA fully biodegradable mulching film and its effect on cotton growth in Shihezi reclamation areas in Xinjiang of China

Abstract: In order to explore the application effect of PBAT/PLA fully biodegradable mulch on Xinjiang cotton, this study selected PBAT/PLA fully biodegradable mulching film as the research object, compared with PE mulching film, carried out PBAT/PLA fully biodegradable mulching film application test in Shihezi reclamation area, investigated the degradation performance change of PBAT/PLA mulching film, and systematically analyzed the degradation performance of PBAT/PLA mulching film and its impact on soil temperature and humidity, cotton growth and yield. The degradation performance of PBAT/PLA mulch and its effects on soil temperature and humidity, cotton growth and yield were systematically analyzed. The results showed that the PE mulch was damaged in different sizes in the field environment, but the characterization test showed that it did not have intrinsic degradation behavior. The degradation rate of PBAT/PLA mulch was fast, and it entered the induction period after covering for 43 days, and from covering for 136 days to cotton harvest, the film was in the fragmentation period. Fourier transform infrared spectroscopy showed that after degradation, PBAT/PLA mulch appeared with a new characteristic absorption peak, and the strength of the group characteristic peak increased. The crystal type analysis showed that the original crystalline type of PBAT/PLA mulch had not changed after degradation, but the crystallization capacity was enhanced. At this stage, PBAT/PLA mulch experienced cross-linking and branching of molecular chains, breaking of molecular chains in the amorphous region, and rearrangement and crystallization of short-chain PBAT. The observation of micromorphology also confirmed that PBAT/PLA mulch had good degradability in the soil cultivation environment. With the early cracking of mulch, the full bud stage, flowering stage and boll opening stage of cotton in PBAT/PLA mulch group were 1 d, 3 d, and 3 d later than those in the PE mulch group, respectively. In the early stage of cotton growth, the PBAT/PLA mulch surface remained complete, the effect of increasing temperature and preserving moisture was good, and the seedling emergence rate of the two groups was comparable. However, as the PBAT/PLA mulch gradually cracked, its application effect began to decline. After cotton entered the full bud stage, the soil temperature and water content under PBAT/PLA mulch were 0.30-1.15℃ and 2.31-3.46 percentage points lower than those under PE mulch, respectively. Ultimately, the plant height and stem diameter of the PBAT/PLA mulch group were 22.08% and 12.82% lower than those of the PE mulch group, respectively, and the seed cotton yield was 20.24% lower. Therefore, the biodegradable mulch formula with PBAT/PLA as the main raw material needs to be further improved, especially in terms of the regulation of degradation performance. It is urgent to design the molecular chain structure of the material, postpone its degradation induction stage to match the needs of cotton for temperature increase and moisture preservation, and realize rapid degradation after cotton enters the boll opening stage, so as to hopefully replace PE mulch in the cotton production system in the Shihezi Reclamation Area, Xinjiang. This paper provides a reference for further research and development of biodegradable mulching film suitable for cotton production in Xinjiang.