Seed priming of entomopathogenic fungi to increase maize crop growth and tolerance against herbivores

A group from State Key Laboratory for Biology of Plant Diseases and Insect Pest, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China, etc. has reported seed priming of entomopathogenic fungi to increase crop growth and tolerance against herbivores.

Ostrinia furnacalis is the most destructive pest of maize causing an annual yield loss of about 6 to 9 million tons in East and Southeast Asia.

Seed priming is nowadays considered one the most promising techniques in enhancing abiotic and biotic stress tolerance, yield, and growth in crop plants. In this study, seed priming using Beauveria bassiana (BB) and Trichoderma asperellum (TA) were evaluated.

From the experimental results, the additional yield and gross return were calculated to estimate the increase in corn yield and economic return by the seed priming of entomopathogenic fungi. The highest additional yield of 6811.62 KG/ha and 8117.45 KG/ha in year 2018 and 2019 respectively was recorded in consortium treatment (BT), which is an increase of 82 – 96% over control. Treatment by BB and TA resulted in additional yield of 4518.06 (52.2%) and 2930.19 (35.4%) respectively in 2018 year and 4688.58 (55.8%) and 3982.40 (47.5%) in 2019 over control.

The effect of seed priming of entomopathogenic fungi was seen in O. furnacalis larval development, especially in consortium inoculated plants (BT). The growth speed was greatly reduced and larval survival rate was also reduced. It was seen that more then 50% larvae cannot even reached at 3rd instar stage and died. The lowest survival rate of 13% was recorded in consortium (BT) treated plants followed by 28% in B. bassiana (BB) and 36% in T. asperellum (TA) was recorded whereas the survival rate in control group was 94%.

Leaf samples of seed primed and non-primed maize under O. furnacalis stress were analyzed for antioxidants, proline, and chlorophyll content. Seed priming with fungal strains significantly increased the enzyme activities at 24-h by the consortium treatment (BT) compared to non-primed control (IC). The seed priming with BT significantly enhanced the SOD, POD, Protease, PPO, and Proline activities up to 80.29-, 336-, 302-, 141-, and 65.8-fold respectively. And further, O. furnacalis infestation significantly increased cis-OPDA, JA, and JA-Ile in all fungal inoculated treatments (BB, TA, BT) but the highest phytohormone content was observed in consortium treated plants (BT), suggesting that the entomopathogenic fungal inoculation., especially consortium (BT) induced the enhanced production of JA metabolites in maize.