Enhancement of peanut Fe nutrition under field conditions by PDMA
The effect of PDMA on peanut Fe nutrition was investigated further under field conditions (Fig. 5). As shown in Fig. 5a, PDMA treatment resulted in a 6.7% increase in the SPAD value of young leaves compared with control plants at 67 dps (pod-bearing stage). At 107 dps (fruit-ripening stage), peanut plants treated with PDMA, PDMA–Fe, and EDTA–Fe exhibited greatly promoted SPAD values in young leaves, higher by 10.4%, 11.8%, and 10.6%, respectively, compared with the control. Moreover, significant increases of 50.2%, 50.3%, and 45% were found in the active Fe concentrations of young leaves following PDMA, PDMA–Fe, and EDTA–Fe treatment, respectively (Fig. 5b). PDMA and PDMA–Fe treatment produced slightly higher increases than EDTA–Fe treatment, but the differences were not significant. These results demonstrate the great capabilities of PDMA and PDMA–Fe in relieving Fe deficiencies in peanut plants under field conditions.