Effect of plant growth regulators DA-6 and COS on drought tolerance of pineapple through bromelain and oxidative stress

Abstract

Background: Due to global warming, drought climates frequently occur on land, and despite being drought resistant, pineapples are still subjected to varying degrees of drought stress. Plant growth regulators can regulate the stress tolerance of plants through hormonal effects. This experiment aims to investigate the regulatory effects of different plant growth regulators on Tainong- 16 and MD-2 Pineapple when subjected to drought stress.

Results: In this experiment, we examined the regulatory effects of two different plant growth regulators, sprayed on two pineapple varieties: MD-2 Pineapple and Tainong-16. The main component of T1 was diethyl aminoethyl hexanoate (DA-6) and that of T2 is chitosan oligosaccharide (COS). An environment similar to a natural drought was simulated in the drought stress treatments. Then, pineapples at different periods were sampled and a series of indicators were measured. The experimental results showed that the drought treatments treated with T1 and T2 plant growth regulators had a decrease in malondialdehyde, an increase in bromelain and antioxidant enzyme indicators, and an increase in phenotypic and yield indicators.

Conclusion: This experiment demonstrated that DA-6 and COS can enhance the drought resistance of pineapple plants to a certain extent through bromelain and oxidative stress. Therefore, DA-6 and COS have potential applications and this experiment lays the foundation for further research.

Keywords: Bromelain; Drought; Oxidative stress; Pineapple; Plant growth regulators.

Fig. 1

The soil volumetric water content during the five periods in MD-2 Pineapple (A) and Tainong-16 (B) treatments

Fig. 2

The activities of bromelain during the eleventh periods in MD-2 Pineapple (A) and Tainong-16 (B) treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. Lower case letters above columns indicate significant difference (p<0.05)among treatments

Fig. 3

The activities of SOD in MD-2 Pineapple (A) and Tainong-16 (B) treatments between different periods and different treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. Lower case letters above columns indicate significant difference (p<0.05)within treatments. Capital letters above columns indicate significant difference (p<0.05) among treatments

Fig. 4

The activities of POD in MD-2 Pineapple (A) and Tainong-16 (B) treatments between different periods and different treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. Lower case letters above columns indicate significant difference (p<0.05)within treatments. Capital letters above columns indicate significant difference (p<0.05) among treatments

Fig. 5

The activities of CAT in MD-2 Pineapple (A) and Tainong-16 (B) treatments between different periods and different treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. Lower case letters above columns indicate significant difference (p<0.05)within treatments. Capital letters above columns indicate significant difference (p<0.05) among treatments

Fig. 6

The activities of APX in MD-2 Pineapple (A) and Tainong-16 (B) treatments between different periods and different treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. Lower case letters above columns indicate significant difference (p<0.05)within treatments. Capital letters above columns indicate significant difference (p<0.05) among treatments

Fig. 7

The content of MDA in MD-2 Pineapple (A) and Tainong-16 (B) treatments between different periods and different treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. Lower case letters above columns indicate significant difference (p<0.05)within treatments. Capital letters above columns indicate significant difference (p<0.05) among treatments

Fig. 8

The correlations between the leaf length of the longest leaf (LL), the leaf width of the longest leaf (WL), the leaf number (NL), the leaf fresh weight (LFW), the leaf dry weight (LDW), the leaf area (LA) in MD-2 Pineapple (A) and Tainong-16 (B) treatments. * indicates significant correlation at 0.05 level; ** indicates significant correlation at 0.01 level

Fig. 9

The content of fruit weight in MD-2 Pineapple (A) and Tainong-16 (C) treatments. The correlations between the fruit length (FL), the fruit width (FW), the fruit weight (FZ) in MD-2 Pineapple (B) and Tainong-16 (D) treatments. Values are presented as the mean ± SE (n = 4) of four biological replicates. * indicates significant correlation at 0.05 level; ** indicates significant correlation at 0.01 level