Abstract:

To provide a theoretical basis for scientific nitrogen fertilization, increasing yield and economic benefits, and reducing environmental risks, the effects of nitrogen application rate and nitrogen fertilizer type on potato growth, development and nitrogen utilization were studied. Using ‘Xisen 6’ and ‘Chuanyu 62’ as test materials, a randomized block design was employed with five nitrogen application treatments, including a nitrogen-free control (CK), conventional urea nitrogen at 67.5 kg/hm², slow-release urea nitrogen at 67.5 kg/hm², conventional urea nitrogen at 135 kg/hm², and slow-release urea nitrogen at 135 kg/hm². The results showed that the emergence occurred earlier under low nitrogen treatments compared to high nitrogen treatments. At the same growth stage and nitrogen application level, the emergence rate was higher under slow-release nitrogen fertilizer treatments than that of conventional nitrogen fertilizer treatments. With increasing nitrogen application rate, plant height, leaf area index, and chlorophyll content increased for both varieties. However, excessive nitrogen application reduced stem diameter. Agronomic traits were superior under slow-release nitrogen fertilizer treatments compared to conventional nitrogen fertilizer treatments. Plant nitrogen accumulation increased with higher nitrogen application rates. However, nitrogen agronomic efficiency, nitrogen production efficiency, nitrogen uptake efficiency and nitrogen use efficiency (NUE) significantly decreased. At the same nitrogen application level, NUE was better under slow-release nitrogen fertilizer treatments than under conventional nitrogen fertilizer treatments. Within the experimental range, for ‘Xisen 6’, yield increased significantly with increasing nitrogen application. At the same nitrogen level, yields under slow-release nitrogen fertilizer treatments were significantly higher than under conventional nitrogen fertilizer treatments. The highest yield (58000.3 kg/hm²) was achieved with the 135.0 kg/hm² slow-release nitrogen treatment, representing a 16.7% increase compared to the same rate of conventional nitrogen fertilizer. The yield of ‘Chuanyu 62’ increased first and then decreased with the increase of nitrogen application rate, and the differences among treatments were significant. The highest yield was achieved under the treatment of 67.5 kg/hm² of slow-release nitrogen fertilizer, reaching 43294.2 kg/hm², which was significantly higher than that of the control (CK), compared with the conventional nitrogen fertilizer treatment at the same nitrogen application rate, the yield increased by 5.2%. Compared to conventional nitrogen fertilizer treatments, slow-release nitrogen fertilizer treatments also resulted in better marketable tuber rates and harvest indices. Scientific nitrogen application promoted plant growth and optimized dry matter accumulation and partitioning. Slow-release nitrogen fertilizer significantly improved emergence rate, facilitated higher plant nitrogen accumulation, and enhanced nitrogen use efficiency. Under the ecological conditions of this experimental region, applying slow-release nitrogen fertilizer at 135.0 kg/hm² for mid-maturing varieties (such as ‘Xisen 6’) and at 67.5 kg/hm² for mid-late maturing varieties (such as ‘Chuanyu 62’) can achieve higher yields and economic benefits.

Key words: potato, slow-release nitrogen, nitrogen use efficiency, agronomic traits, dry matter accumulation