Phthalanilic Acid with Biostimulatory Functions Affects Photosynthetic and Antioxidant Capacity and Improves Fruit Quality and Yield in Cowpea (Vigna unguiculata (L.) Walp.)

Ting Ma,Qiong Wu,Rong Zhang,Zhiqing Ma,Na Liu

doi:10.3390/agriculture11111082

Abstract

The widespread application of biostimulants with a growing trend represents sustainable practices aimed at improving growth and yield and alleviating stresses in green agricultural system. Phthalanilic acid (PPA), with biostimulatory functions, has been increasingly applied to fruit and vegetable production. However, its specific biostimulatory effects on growth and development of cowpea (Vigna unguiculata) plants is still unclear. In this study, the regulatory function of foliar spraying PPA at the flowering timing in morphometric (length, width, single pod weight and yield), physiological (relative electrical conductivity), and biochemical (antioxidant enzymes activity, photosynthetic pigment, malondialdehyde, vitamin C, soluble protein, and soluble sugar content) parameters of cowpea plants were investigated. In general, PPA treatments exhibited higher antioxidant enzymes activities (with an increase of 11.89–51.62% in POD), lower relative conductivity (with a decrease of 22.66–62.18%), increased photosynthetic pigment levels and amounts of free proline (with an increase of 24.62–90.52%), and decreased malondialdehyde. Furthermore, the length, width and weight of single pod, podding rate (with an increase of 19.64%), vitamin C, soluble protein (with an increase of 18.75%), and soluble sugar content were increased by 200 mg·L−1 PPA. These data, together with an increased yield of 15.89%, suggest that PPA positively regulates the growth and development, improving fruit quality and yield, especially at 200 mg·L−1. This study indicates that PPA has biostimulatory effects in cowpea production and shows application prospect in field cultivation.

Highlights

Better fruit quality and higher yield are always the goals for agricultural production.abiotic stresses, such as drought, salinity, heat, and chill, severely threaten field cultivation
Compared with the blank control, at the full-bloom period, photosynthetic rate (Pn) increased by 15.31%
At the early podding period, and Pn increased by 21.98–28.84% under three PPA treatments (Figure 1A)

Summary

Introduction

Better fruit quality and higher yield are always the goals for agricultural production. Abiotic stresses, such as drought, salinity, heat, and chill, severely threaten field cultivation. The applications of biostimulants have become an effective strategy for the enhancement of sustainable practices to mitigate stresses and improve growth and yield by regulating plant physiological and biochemical processes in field green production [1,2,3,4]. Apart from the mixture, some small molecules, showing biostimulatory effects, positively alert physiological and biochemical processes, including seed germination, root nodulation formation of legume crops, light utilization, crop nutrient absorption, and adverse stresses tolerance [14,15,16,17,18]. Brassinolide application improved the drought tolerance in maize through modulation of enzymatic antioxidants and leaf gas exchange [21]

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Results

Discussion

Conclusion