Multiple sources of microplastics (MPs) in farmland could result in the changing of microbial community and the plant growth. Most studies of MPs in agricultural system have focused on the effects of single types of MPs on growth of plants, while neglect interactions between multiple types of MPs. In this study a pot-experiment was conducted to investigate the effects of multiple types of MPs, including polystyrene beads: M1, 5 μm, M2, 70 nm and degradable mulching film (DMF) fragments on growth of wheat seedlings and associated rhizosphere microbial community. CKD (adding DMF) significantly reduced plant height and base diameter of wheat seedlings. DMF in combination with M2, significantly increased plant height and aboveground biomass, but decreased the base diameter. Actinobacteria was the dominant taxa in the rhizosphere bacterial community in various treatments. PCoA analysis showed that the bacterial composition in M2HD (100 mg kg⁻¹ M² with DMF) was significantly different from that of CKD and M2LD (10 mg kg⁻¹ M² with DMF). At the level of genera, the dominant fungi in CKD and M2LD were in the genus Fusarium, which is the cause of wheat fusarium blight and Alternaria, which results in decreased base diameter. In CK (control group) and M2HD, Blastobotrys exhibited the greatest abundance, which assisted wheat seedlings in resisting Verticillium disease. Cluster and PCoA analysis showed the fungal composition in CKD was significantly different from CK, M2LD and M2HD. These findings suggest MPs potentially have selective effects on pathogens that affect growth of plants and potentially safety of the food.

Thifluzamide fungicide is widely used to protect rice (Oryza sativa) against the sheath blight fungus (Rhizoctonia solani). The continuous application of thifluzamide may lead to accumulation in soil and contaminate rice crop. To sustain the environment, it is necessary to assess its accumulation and degradation in field. The method limit of detection (LOD) was 0.022 ng. The limits of quantitation detection (LOQ) were 5.0 μg L⁻¹in water and 4.0 μg kg⁻¹in paddy soil and rice crop. In this study, a 2-year (2011–2012) field study was performed to monitor thifluzamide degradation in the rice production areas of Nanjing, Xiaoxian, and Changsha. The degradation dynamics of thifluzamide in paddy water, paddy soil, and rice crop were well described by the first-order kinetics equation. The 2-year average half-lives of thifluzamide in paddy water, paddy soil, and rice crop were 26.19, 17.92, 14.61 days (Nanjing), 15.63, 20.71, 9.10 days (Xiaoxian), and 9.47, 13.92, 10.08 days (Changsha), respectively. Thifluzamide degraded more rapidly in rice crop than in soil and paddy water. The variation in thifluzamide degradation was attributed to the difference in rainfall during the period of rice cultivation. The maximum residue of thifluzamide in brown rice was 0.0303 mg kg⁻¹in Nanjing and the residue of thifluzamide in brown rice was not detected in other two sites before thifluzamide was applied at pre-harvest. The experimental data demonstrated that thifluzamide recommended dosage of 72 g a.i.ha⁻¹can be used in rice fields with less than three times within a 30-day time interval.

Environmental risk assessment of GM crops in Europe proceeds by step-wise estimation of effect, first in the plant, then the field plot (e.g. 10–100 m⁻²), field (1000–10,000 m⁻²) and lastly in the environment in which the crop would be grown (100–10,000 km²). Processes that operate at large scales, such as cycling of carbon (C) and nitrogen (N), are difficult to predict from plot scales. Here, a procedure is illustrated in which plot scale data on yield (offtake) and N inputs for blight resistant (both GM and non-GM) and blight-susceptible potato are upscaled by a model of crop resource use to give a set of indicators and metrics defining N uptake and release in realistic crop sequences. The greatest potential damage to environment is due to loss of N from the field after potato harvest, mainly because of the large quantity of mineral and plant matter, high in N, that may die or be left in the field. Blight infection intensifies this loss, since less fertiliser N is taken up by plants and more (as a proportion of plant mass) is returned to the soil. In a simulation based on actual crop sequences, N returns at harvest of potato were raised from 100 kg ha⁻¹ in resistant to 150 kg ha⁻¹ in susceptible varieties subject to a 40% yield loss. Based on estimates that blight-resistant types would require ~20% of the fungicide applied to susceptible types, introduction of resistant types into a realistic 6-year cropping sequence would reduce overall fungicide use to between 72 and 54% depending on the inputs to other crops in the sequence.

Tebuconazole is a broad-spectrum fungicide extensively used worldwide for the control of many diseases such as powdery mildew and scab in apple, early blight of tomato, anthracnose of chilli, white rot and purple blotch of onion etc. Maximum residue level of this compound has not been worked out on these crops in India; the persistence and dissipation kinetics of tebuconazole on apple, tomato, chilli and onion were studied following three foliar applications of the formulation Folicur 430 SC at a standard dose (X) 322, 268.75, 215 and 215 g a.i./ha and at double dose (2X) 645, 537.5, 430 and 430 g a.i./ha, respectively, to work out the safe waiting periods and half-life period of tebuconazole. Extraction was done using QuEChERS method and cleanup by using dispersive solid-phase method. Tebuconazole residues were estimated on gas chromatograph-mass spectrometry (GC-MS). The recovery of tebuconazole in fortified matrix was above 90% with a limit of quantification (LOQ) at 0.05 mg kg⁻¹. The initial deposits of tebuconazole on apple at two locations under study ranged from 1.986–2.011 mg kg⁻¹at X dose to 3.698–3.843 mg kg⁻¹ at 2X dose. The initial deposits in tomato, chilli and onion were 1.129, 1.760 and 1.169 mg kg⁻¹ at X dose and 2.213, 2.784 and 2.340 mg kg⁻¹, respectively at the 2X dose. Dissipation of the fungicide followed first-order of kinetics and the half life of degradation ranged from 1.30–2.25 days at X dose to 1.40–2.62 days at 2X days on different crops under study. Residues declined below the determination limit (LOQ) of 15 and 20 days after spraying, respectively, at X and 2X dose in apple; 7 and 10 days in tomato; 10 and 15 days in chilli and onion. Waiting periods of 5, 2, 7 and 12 days, respectively, are suggested for apple, tomato, chilli and onion at 2X dose.