Biodegradable plastic film provides a new way to solve “white pollution”. However, there is an urgent need to solve the problems of residual plastic film and tail vegetable pollution after planting. Currently, the continuous degradation of polyethylene plastic film and biodegradable plastic film after returning to the field and their impact on soil environment and vegetable crop growth need further research. This study is expected to provide some theoretical support through residual membrane addition experiments. We uniformly buried PBAT/PLA humic acid biodegradable film (BIO1), PBAT/PLA-lignin biodegradable film (BIO2), and polyethylene film (PE) at 200 kg film residue per ha in potted soil. After burial 120 d, the crystallinity of BIO1 and BIO2 residue decreased by 7.37% and 3.91% respectively, compared to that of PE. Additionally, the water contact angle of BIO1 and BIO2 film was lower, and the weight loss rate significantly increased. Microplastics (polyethylene) abundance in the PE treatment substrate was (166.67 ± 169.96) n ·kg⁻¹ after 150 days of burial, and microplastics (PBAT/PLA) were not found in BIO1 and BIO2 treatments in this study. Residual film reduced the percentage of 2-1 mm and >2 mm water-stable agglomerates and increased the percentage of < 0.25 mm water-stable agglomerates, ledto soil compaction and water upward migration; reduced urease and sucrase activities in substrate, further reduced root vigor and increased leaf proline content, eventually reduced tomato yield. However, compared with PE, BIO1 have lower substrate volumetric weight, higher aeration porosity, alleviated soil compaction, stronger substrate enzyme activity and root activity, residues significantly increased soil Ascomycota relative abundance and decreased Zoopagomycota relative abundance; reduced leaf proline content, significantly increased tomato yield, and improved tomato quality by significantly increasing lycopene content by 12.80%. Overall, 200 kg · ha⁻¹ of residual humic acid biodegradable plastic film can improve tomato quality, reduce “white pollution”, and reduce microplastic residues caused by residual film in a solar greenhouse.

The G protein α-subunit, GPA1, is an integral component of several signaling pathways in plants, including response to abiotic stress. However, the molecular mechanism behind these processes remains largely unknown in the cucumber plant (Cucumis sativus L.). In order to further understand the role of CsGPA1 in cucumber under drought stress, changes in plant growth, physiological parameters, and gene expression of CsAQPs were all measured under water stress induced by polyethylene glycol (PEG) using wild type (WT) and CsGPA1-interference (RNAi) cucumber seedlings. Our results demonstrated that the RNAi plants had lower drought tolerance, displaying seriously withered leaves, lower relative growth rate, lower root-shoot ratio, and lower root activity under drought stress compared to WT plants. Physiological studies indicated that the suppression of CsGPA1 weakened drought stress tolerance due to higher water loss rate in the leaves, higher levels of hydrogen peroxide (H₂O₂), increased malondialdehyde (MDA) content, lower free proline content, lower soluble sugar content, lower soluble protein content, and decreased antioxidant enzyme activities. qRT-PCR analysis demonstrated that the interference of CsGPA1 up-regulated the expression of most AQP genes (except for CsPIP2;3 in leaves) and down-regulated the expression of CsPIP1;2, CsPIP1;4, CsPIP2;1, and CsPIP2;4 in roots under drought stress when compared to WT plants. Our results demonstrated that CsGPA1 could function as a positive regulator in drought stress response by decreasing the accumulation of reactive oxygen species (ROS), improving permeable potentials, and reducing water loss in cucumber plants.