Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. Studies have been conducted on the distribution and impact of plastic pollution in marine ecosystems, but little is known on terrestrial ecosystems. Plastic mulch has been widely used to increase crop yields worldwide, yet the impact of plastic residues in cropland soils to soil health and crop production in the long term remained unclear. In this paper, using a global meta-analysis, we found that the use of plastic mulch can indeed increase crop yields on average by 25%-42% in the immediate season due to the increase of soil temperature (+8%) and moisture (+17%). S U PP O RTI N G I N FO R M ATI O NAdditional supporting information may be found online in the Supporting Information section. How to cite this article: Zhang D, Ng EL, Hu W, et al. Plastic pollution in croplands threatens long-term food security. Glob Change Biol. 2020;26:3356-3367. https://doi.

The aim of this study was to investigate the effect of platelet-rich plasma (PRP) on cavernous nerve (CN) regeneration and functional status in a nerve-crush rat model. Twenty-four Sprague-Dawley male rats were randomly divided into three equal groups: eight had a sham operation, eight underwent bilateral nerve crushing with no further intervention and eight underwent bilateral nerve crushing with an immediate application of PRP on the site of injury. Erectile function was assessed by CN electrostimulation at 3 months and nerve regeneration was assessed by toluidine blue staining of CN and nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase staining of penile tissue. Three months after surgery, in the group that underwent bilateral nerve crushing with no further intervention, the functional evaluation showed a lower mean maximal intracavernous pressure (ICP) and maximal ICP per mean arterial pressure (MAP) with CN stimulation than those in the sham group. In the group with an immediate application of PRP, the mean maximal ICP and maximal ICP/MAP were significantly higher than those in the injured control group. Histologically, the group with the application of PRP had more myelinated axons of CNs and more NADPH-diaphorase-positive nerve fibres than the injured control group but fewer than the sham group. These results show that the application of PRP to the site of CN-crush injury facilitates nerve regeneration and recovery of erectile function. Our research indicates that clinical application of PRP has potential repairing effect on CN and peripheral nerves.

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Ammonia (NH 3 ) volatilization was measured with the continuous airflow enclosure chamber method under different urea application amounts using pots in paddy fields in Erhai Lake Watershed, China. Several factors, such as the urea nitrogen application amount, days after fertilization, NH 4 ? -N concentration and pH of surface water, and climate, that could affect ammonia volatilization were also studied. The results indicated that ammonia volatilization loss increased linearly with increasing amounts of applied urea. The ratios of the ammonia volatilization loss to the applied nitrogen ranged from 16.59 to 18.43 % with different nitrogen application amounts. The ammonia volatilization loss peaked within the first 3 days after fertilization, which accounted for 65-82 % of the total ammonia loss in each period. We observed the following degree of the effects of various factors on ammonia volatilization: NH 4 ? -N concentration of surface water [ urea application amount [ pH of surface water [ days after fertilization [ water temperature of surface water. The wind velocity and rainfall were the key factors affecting ammonia volatilization. The model of ammonia volatilization flux was established by using the measured dates from 2013 and was represented as Y = 0.008(x 1 ? x 2 ? x 3 ) ? e 0.056x4-0.068x5 -0.623 (R 2 = 0.81, P \ 0.0001). The model was verified by using the measured dates from 2012. The calculated values fitted well with the field observations. However, the model parameters need to be amended using the model to predict the ammonia volatilization flux in the rice season from other regions.

OBJECTIVETo explore the expression of transforming growth factor‐β1 (TGF‐β1) in penile tissue from rats after bilateral cavernosal nerve (CN) ablation, mimicking patients who have had no nerve‐sparing during prostatectomy.MATERIALS AND METHODSTen adult male rats (neurectomy group) had a bilateral CN resection aseptically under an operating microscope, with six sham‐operated rats as controls. Fifteen weeks after surgery an apomorphine test was used in all rats to assess penile erection. The penile specimens were then collected and prepared for detecting the expression of TGF‐β1 by reverse transcription‐polymerase chain reaction (RT‐PCR), western blot and immunohistochemistry, and for quantitative analysis of the ratio of smooth muscle to collagen fibres in the corpus cavernosum with confocal microscopy.RESULTSAll rats in the sham‐operated group but none after neurectomy had an erectile response after subcutaneous injection with apomorphine (100 µg/kg). Immunohistochemistry, RT‐PCR and western blot analyses showed a significantly higher expression of TGF‐β1 in the penile tissues after neurectomy than after sham surgery. Smooth muscle cells (fluorescing red) and collagen fibres (green autofluorescence) after paraformaldehyde fixation, were clearly identified by confocal microscopy. The fluorescence intensity expressed as the mean (sem) ratio of smooth muscle to collagen fibres in the corpus cavernosum after neurectomy was 0.265 (0.125), significantly lower than that in the sham‐operated group, at 0.760 (0.196) (P < 0.01).CONCLUSIONAn increased expression of TGF‐β1 in penile tissue which promotes the synthesis of collagen may be one of the important factors for the erectile dysfunction caused by bilateral CN ablation. Similar pathophysiological processes may occur in the corpus cavernosum of patients after radical prostatectomy.