Appropriate N application alleviates growth inhibition of okra (Abelmoschus esculentus L. Moench) caused by fluctuating soil moisture

Abstract

Abstract Uneven rainfall in the context of global warming can cause soil moisture fluctuation (SMF) that harm crop growth, and it is not yet known whether nitrogen (N) can mitigate the harm caused by the strong SMF. This paper uses okra as a test subject and sets three SMFs of 45–55% FC (W1), 35–65% FC (W2), and 25–75% FC (W3) and three N applications of 0 kg hm− 2 (N0), 110 kg hm− 2 (N1), and 330 kg hm− 2 (N2) to investigate the effects of SMF and N application on physiological and biochemical aspects of okra. The results showed that okra stem diameter, number of leaves, photosynthesis characteristics, antioxidant enzyme activity, and yield were the highest under N1 treatment and considerably greater than under N0 and N2 treatments; stomatal density, antioxidant enzyme activity, malondialdehyde content, and proline content of okra leaves were the highest under W3 treatment, indicating that the plants were subjected to duress under W3 treatment; the N1W1 treatment had the highest okra stem diameter, leaf number, photosynthetic characteristics, and yield, including a yield of 201.3g, which was higher than the lowest treatment (N2W3), a significant increase of 67.8%; W3 was detrimental to okra growth, while the agronomic traits and yields of okra in the N1 treatment were higher than those in the N0 and N1 treatments, indicating that the crop damage caused by W3 could be mitigated by the appropriate amount of N application.