Abstract: This study aimed to assess the effects of reducing nitrogen application on growth and yield formation of rainfed peanut in a semiarid region of western Liaoning Province. The testing peanut variety was ‘Baisha 1016’. A two-year experiment (2018-2019) was conducted with four nitrogen application levels, including no nitrogen (N0), low nitrogen (N1, 40 kg·hm^-2), medium nitrogen (N2, 80 kg·hm^-2) and high nitrogen (N3, 120 kg·hm^-2). There were substantial spatial-temporal variations of precipitation in western Liaoning, with 2018 being a dry year and 2019 being a wet year. Due to water limitation, increasing nitrogen application rate did not significantly affect peanut yield and aboveground dry matter in both years. Because of drought at early stage in 2018, the pod number per unit area was significantly lower than that in 2019 (P<0.01). Under high nitrogen rate, seed number per pod decreased in 2018 but was higher than that in 2019 (P<0.01). There was no significant difference in 100-seed weight between those two years. In 2018, nitrogen application effect was limited by water shortage, which directly impacted leaf growth. In 2019, water and nitrogen were not well coordinated in the growing season, thus resulting in no significant difference of dry matter among different treatments. However, high nitrogen rate shortened the time for peanut to reach maximum dry matter and maximum growth rate. Compared with 2018, high nitrogen rate increased stem and leaf dry matter formation in 2019, but without statistical significance. Therefore, low nitrogen application (40 kg·hm^-2) could be applied in this semiarid region. Such a scheme of nitrogen application would not affect the growth of peanut, and the pollution of cropland and groundwater would be largely reduced, which is conducive to sustainable land use. Our results provide a reference for reducing nitrogen application, increasing peanut yield, and ensuring food security in semi-arid regions.

Key words: peanut, reduction of nitrogen application, yield, yield component, dry matter.