Combination of salicylic acid and ultrasonication for alleviating chilling injury symptoms of longkong

Objectives Chilling injury is a prominent physiological disorder in longkong fruit pericarp when stored under 13℃for a prolonged period.This study aimed to investigate the effects of individual salicylic acid(SA)and ultrasonication(US)treatments and of the combination salicylic acid and ultrasonication(SA-US)on alleviating the chilling injury symptoms in longkong fruit pericarp when in prolonged cold storage.Materials and Methods SA(1 mmol/L)and US(40 kHz,10 min at 90%amplitude,350 W)were used as individual and combined(SA-US)treat-ments to control the chilling injury in longkong pericarp.The various quality measures were checked every 2 d in longkong for up to 18 d of cold storage(13℃,90%relative humidity).Results The results revealed that the control fruits treated with water exhibited severe chilling injury symptoms followed in rank order by US,SA,and SA-US cases.Treatments such as US and SA alone were more effective in controlling chilling injuries than control,while only minimal signifi-cant differences were noticed between them.On the other hand,the longkong pericarp treated with the SA-US combination had significantly increased antioxidant enzyme(superoxide dismutase and catalase)activities and decreased levels of membrane lytic(phospholipase D and lipoxygenase)enzymes and browning-inducing enzymes(phenylalanine ammonia lyase and polyphenol oxidase).Consequently,in the longkong pericarp,the chilling injury index,electrolytic leakage,respiration rate,weight loss,firmness,malondialdehyde content,changes in unsaturated and saturated fatty acid contents,and reactive oxygen species were significantly controlled by this treatment.Conclusions The present study concludes that longkong fruit treatment with a combination of US and SA is an excellent alternative for control-ling the chilling injury symptoms and extending the shelf-life.

Plant Growth Promoting Rhizobacteria as Biological Control Agent in Rice

The use of agrochemical products to combat diseases in crops has adverse effects on the environment and human health. Plant growth promoting rhizobacterium (PGPR) has been increasingly proposed as an eco-friendly alternative in agriculture. PGPRs have beneficial effects not only in promoting plant growth but also have shown their potential as biological control agent, being able to inhibit plant pathogens. Here, we investigated the use of PGPR Paraburkholderia sp. strain SOS3 to provide disease protection in rice (Oryza sativa L.). The antagonistic activity of SOS3 against five fungal pathogens of rice was assessed by dual culture on plates and on rice seedlings. The results showed that on plate assay, SOS3 inhibits the growth of Curvularia lunata, Rhizoctonia solani, Pyricularia oryzae, Helminthosporium oryzae, and Fusarium moniliforme by 17.2%, 1.1%, 8.3%, 32.5%, and 35.4%, respectively. When inoculated on rice seeds, SOS3 promotes seed germination and significantly reduces disease symptoms in plants infected with R. solani. These results suggest that SOS3 has a great potential to be used in rice agriculture to combat the “Sheath Blight” disease.