Effects of single-seed sowing at different densities on nutrient uptake and distribution in peanut

Peanut is an important economic oil crop in China. Traditional double-seed sowing pattern has been the main sowing mode in China because double-seed sowing can avoid low germination rate due to poor quality of peanut seed. However, this sowing mode results in competition between plants in the same hole which intensifies with time and eventually limits plant development. On the other hand, single-seed sowing is a seed-saving and high-yield cultivation pattern, which adjusts population structure and improve single plant productivity by altering sowing pattern and density, can produce high yield. In order to study the process of high yield in single-seed sowing, ‘Huayu 22’ large-seed cultivar of peanut was used to study the difference in absorption regularity and distribution characteristics of N, P₂O₅ and K₂O under high (S1: 270 000 holes·hm^-2), medium (S2: 225 000 holes·hm^-2) and low (S3: 180 000 holes·hm^-2) density conditions, respectively with single-seed sowing and traditional double-seed sowing (CK: 135 000 holes·hm^-2) of groundnut in a field experiment. The results showed that both S1 and S2 increased N, P₂O₅ and K₂O accumulation in both individual plant and population, but the increase in single plant of S1 was smaller than that of S2 treatment. Compared with control at pod-filling stage, the nutrients absorption rate in individual plant (S1) decreased remarkably, and no significant difference in population accumulation was observed in S1. However, nutrient accumulation in both individual plant and population of S2 remained higher level throughout the growing period compared with control, especially, at later growth stage. As for S3, the N, P₂O₅ and K₂O accumulation in individual plant were higher, while they were lower in population than those of the corresponding control. From the perspective of nutrient distribution characteristics, there was similar nutrient absorption trend in different treatments. N, P₂O₅ and K₂O distribution coefficients in pod of both S2 and S3 were significantly higher than those of the control, however, there was no remarkable difference between S1 and the control. Furthermore, peanut pod yield of S2 was highest among the three densities of single-seed sowing treatments, and increased by 8.1% compared with that of the control, followed by that of S1 (2.5%), and that of S3 slightly decreased compared with that of the control. Based on the analysis of yield and yield components, the reason of S2 with highest yield was the rational planting pattern and density, which improved agronomic traits, increased single plant productivity and economic coefficient of peanut. As for S1 treatment, lower economic index due to large plant density induced relative lower yield of individual plant and population, which was no remarkably improved compared with that of control. Although S3 had higher single plant productivity and lower plant density, the yield increase was not noticeable. Thus, in high yield fields, single-seed sowing at density of 225 000 holes per hectare for large-seed peanut variety ‘Huayu 22’ was recommend for balancing the relationship between single plant and population nutrient uptake, improving nutrient absorption and promoting the distribution of nutrients in peanut pods.