Influences of row spacing and weather conditions on warming effectiveness of open-top chambers during grain-filling stage in maize

Climate warming has a significant effect on the cropping systems.Open-top chambers (OTCs) has become a popular warming device to simulate the response of crops to warming, which is one of hotspots in the fields of climate change and agroecology.Water and heat exchange in crop systems varies with field ridge distance, especially under different weather conditions.To figure out the OTCs warming effectiveness among different ridge distance under different weather conditions is of great significance to study the response of cropland to climate warming, but few reports have been well done.Therefore, a field experiment was conducted at Hailun county to simulate OTCs warming effect of the maize system in row spacing of 55 cm, 60 cm, 65 cm and 70 cm with the same seeding density during grain-filling stage, respectively.Savitzky-Golay and accumulation integration were used to analyze the differences in daily canopy temperature inside and outside OTCs.The warming effectiveness of OTCs was measured by three indicators, including amplitude of temperature increase, length of temperature increase and intensity of temperature increase among the treatments.The results showed that the canopy temperature in all row spacing treatments increased when OTCs was used in maize system, and the canopy temperature under row spacing of 65cm increased significantly.Compared with the other treatments, the row spacing of 65cm had the longest duration of temperature increase and the largest intensity of temperature increase.In terms of amplitude of temperature increase, row spacing of 55 cm treatment had larger values than that of 65cm treatment.Both amplitude and intensity of temperature increase were higher during clear days, while lower during the cloudy days.The rainy days had the longest length of temperature increase, while the lowest amplitude and intensity of temperature increase.In conclusion, the results indicated that different row spacing treatments and weather conditions significantly affected the warming effectiveness of the OTCs in maize systems, and the row spacing of 65cm was the best option for temperature increase.