Abstract: Mechanical properties of peanut pod are important reference factors for mechanized harvest, and peg strength and pod rupture force are the key indicators. A total of 173 peanut varieties （lines） were collected to evaluate their peg strength, pod rupture force, seed-setting range, peanut yield and quality with a numerical method. The results showed that there was a widely variation in peg strength （4.35-11.68N）, the plant-petiole dropping force （8.34N） was higher than that of the pod-petiole （7.03N）. 13 peanut lines reached significant or extremely significant levels between plant-petiole and pod-petiole. The significant differences on pod rupture force were detected among three directions. The pod rupture force was minimized when they were in vertical position and maximized when they were in lateral position. The pod layer height of large peanut varieties （lines） was significantly higher than that of small peanut varieties （lines）, however, there was no significant difference in pod layer thickness between large and small peanut varieties （lines）. The peg strength was from the dropping force of pod-petiole （r=0.82, p<0.01）. 51 peanut varieties （lines） showed an increase in pod and seed kernel yield compared to the control. Five and three principal components were extracted by principal component analysis in the mechanical properties and yield and quality traits, and cumulative contribution rate reached 66.73% and 80.33% respectively. Multiple regression analysis showed that pod-petiole dropping, plant-petiole dropping, the ratio of pod-petiole dropping, mature pods peg strength, immature pods peg strength were the main traits affecting peg strength. Finally, a total of 19 peanut varieties （lines） with excellent peg strength and increased production were obtained. This work becomes helpful in design of harvesting machineries, and provides elite lines in breeding for new peanut varieties.

Key words: peanut, peg strength, pod rupture force, seed-setting range, principal component analysis, regression analysis