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Need for research on carbon dioxide effect on trees: Adjunct Professor

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Visiting Adjunct Professor of Agriculture of USP, Professor Ravindra Joshi presenting at the International Conference on Tropical Fruit Pests and Diseases in Malaysia.

There is an urgent need for increased research support to focus on the combined effect of elevated carbon dioxide and other climate change drivers on tri-trophic interactions in tropical fruit bearing trees, says a Visiting Adjunct Professor of Agriculture of The University of the South Pacific (USP), Professor Ravindra Joshi.

He made the comment recently while presenting the lead paper at the International Conference on Tropical Fruit Pests and Diseases, at LeMeridian, KotaKinabalu, Sabah Malaysia on 25-27 September 2018.

This initiative he said will fast-track towards identifying and developing fruit tree species/varieties resilient to changing climate, which could lead to effective adaptation options.

“Future climate change research needs a paradigm shift from impact assessment to developing mathematical models for tropical fruit trees to predict future climate change scenarios and consequences of elevated carbon dioxide and other climate change drivers to address the complex effects on agricultural production and food quality, as well as host trees, insect herbivores and natural enemies, aside from the broader societal concern of food and nutrition security,” he stated.

He noted that elevated atmospheric carbon dioxide may change natural enemy populations on insect herbivores via shifts in the diversity, abundance, and quality of prey, for example, insect size or concentrations of plant-derived toxins; changes in host-searching mechanisms and behavior of their prey.

“Few studies on the effects of elevated carbon dioxide on plant-herbivore interactions have been conducted to test the effects of elevated carbon dioxide on attack rates of herbivores by natural enemies, probably because of the difficulties inherent in maintaining all three trophic levels in laboratory conditions,” he said.

“At this time there is insufficient information to predict whether the bottom-up effects of carbon dioxide on natural enemies will in general be buffered, amplified, or, more likely species-specific,” Professor Joshi said.

He stated that based on the few fruit trees species studied to date, it is likely that the productivity of fruit-bearing trees should increase as a result of enhanced global carbon dioxide concentrations, because of increased plant growth (both above- and below ground), and improved plant water relations (reduced transpiration and increased water-use efficiency).

“But research data to support this contention is lacking. Thus, before definitive predictions can be made, further long-term studies need to be conducted on diverse tropical fruit tree species such as those with single-stems like banana and papaya, and branched, woody stems like avocado, citrus, mango,” he said.

According to Professor Joshi, the effects of elevated atmospheric carbon dioxide on insect pests of fruit bearing trees are largely unknown and have received very little attention in the past.

Most research investigations of extra atmospheric carbon dioxide “fertilizer effect” on staple crops conclude that herbivory arises indirectly from the plant physiological, morphological, and biochemical changes,” he said.

He added that elevated carbon dioxide causes changes in temperature and precipitation, which in insect herbivores is expected to bring about geographical range expansions, shifts in host plants and other insect-plant interactions.

The theme for the conference was “Sustainable solutions for tropical fruit pests and diseases”.

This news item was published on 15 Oct 2018 08:00:56 am. For more information or any High-Res Images, please contact us on email

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