Abstract:

To find out the effect of nitrogen application rate on nodulation characteristics of peanut, ‘Guihua 36’ was used as research material, six treatments of nitrogen application rate were set up, including 0% (N0, no nitrogen application), 25% (N1, small amount of nitrogen application), 50% (N2, moderate nitrogen application), 75% (N3, small amount of decreased nitrogen application), 100% (N4, conventional nitrogen application rate, 67.50 kg/hm²), 150% (N5, large amount of nitrogen application). A randomized block design field trial was conducted to study the effects of different nitrogen application rates on the observed values and variation rules of nodulation characteristics in 33 sampling observations. The results showed that the average values of nodule number and nodule diameter decreased with the increase of nitrogen application rate in the early phase of sampling. The minimum value of average nodule number appeared in N4 treatment and the minimal value of average nodule diameter appeared in N5 treatment in the middle and late period of sampling. The inhibition of nitrogen to amount was the strongest in conventional nitrogen application, and the inhibition to diameter increased with the increase of nitrogen application rate. When any one of the treatments from N0 treatment to N4 treatment was used as a reference, the probability of significant difference between the reference treatment and the adjacent treatment did not reach the probable level in each sampling period, and the increase or decrease of 25% nitrogen application rate did not lead to significant difference in nodule number and nodule diameter when the nitrogen application rate was less than 67.50 kg/hm². The observed value of nodule diameter was probably to decrease significantly in the middle and late sampling period when a large amount of nitrogen was applied, and the observed value of nodule quantity was probably to increase significantly in the late sampling period compared with conventional nitrogen application. In this research, the direct effects of different nitrogen application rates on the number, diameter and variation law of nodules were accurately observed.

Key words: peanut, nitrogen application rate, number of nodules, diameter of nodules