Effects of indole-3-acetic acid and auxin transport inhibitor on auxin distribution and development of peanut at pegging stage

Abstract This study was conducted to determine the effects of indole-3-acetic acid (IAA) and auxin polar transport inhibitor 2,3,5-triiodobenzoic acid (TIBA) on the growth, photosynthetic characteristics of leaves and IAA contents in different parts of peanut cv. Zhonghua 4 at pegging stage. It was found that spraying IAA resulted in an increase in IAA contents of different parts, the photosynthetic rate, and the growth of stem, peg and flower at pegging stage. Treatment with TIBA increased the first branch length and branch number per plant by 6.83% and 15.34%, while the stem height, peg length, flower number and peg number per plant were significantly inhibited by 25.08%, 29.52%, 33.18% and 30.14%. The average weights of single pod and the yield per pot with auxin and TIBA treatments were distinctly higher than the control. Pegging rate and net photosynthesis rate were enhanced by 4.56% and 12.67%, respectively, but intercellular CO2 concentration (Ci) was decreased than the control by 8.06% under 10 μM TIBA treatment. The IAA contents of stems and leaves treated with 10 μM TIBA were also significantly increased. These results suggest that auxin, along with its transport and distribution, control the growth of peanut at pegging stage, which may contribute to higher yield through enhanced pod development.