Small temperature variations are a key regulator of reproductive growth and assimilate storage in oil palm (Elaeis guineensis)

Naoki Tani,Akiko Satake,Othman Sulaiman,Rokiah Hashim,Toshiaki Kondo,Zubaidah Aimi Abdul Hamid,Akihiko Kosugi,Takamitsu Arai,Natra Joseph

doi:10.1038/s41598-019-57170-8

Abstract

Oil palm is an important crop for global vegetable oil production, and is widely grown in the humid tropical regions of Southeast Asia. Projected future climate change may well threaten palm oil production. However, oil palm plantations currently produce large amounts of unutilised biological waste. Oil palm stems – which comprise two-thirds of the waste - are especially relevant because they can contain high levels of non-structural carbohydrates (NSC) that can serve as feedstock for biorefineries. The NSC in stem are also considered a potent buffer to source-sink imbalances. In the present study, we monitored stem NSC levels and female reproductive growth. We then applied convergent cross mapping (CCM) to assess the causal relationship between the time-series. Mutual causal relationships between female reproductive growth and the stem NSC were detected, with the exception of a relationship between female reproductive organ growth and starch levels. The NSC levels were also influenced by long-term cumulative temperature, with the relationship showing a seven-month time lag. The dynamic between NSC levels and long-term cumulative rainfall showed a shorter time lag. The lower temperatures and higher cumulative rainfall observed from October to December identify this as a period with maximum stem NSC stocks.

Highlights

Oil palm is an important crop for global vegetable oil production, and is widely grown in the humid tropical regions of Southeast Asia
The two biological traits investigated in this study were mutually related to each other except for the causal relationship from female reproductive organ (FRO) growth to starch amounts in the stem
Corley et al.[18] showed that dry weight of reproductive bunches per palm per year is equivalent as dry weight of vegetative parts per palm per year, which indicates that substantial large allocation of photosynthesis assimilates into reproductive bunches

Summary

Introduction

Oil palm is an important crop for global vegetable oil production, and is widely grown in the humid tropical regions of Southeast Asia. The NSC levels were influenced by long-term cumulative temperature, with the relationship showing a sevenmonth time lag. 85% of all palm oil production is confined to a restricted area that is primarily within the countries of Indonesia and Malaysia In this way, the uneven distribution of oil palm cultivation areas makes plants vulnerable to the unfavourable conditions caused by climate anomalies. The NSC in oil palm stem serve as the main buffer against fluctuations in carbon assimilation rates under source-sink imbalances[13], and the production and storage of NSC are affected by various abiotic and biotic factors[14]. It is necessary to investigate how environmental conditions and biotic factors influence oil palm phenotypes, which can be followed through reproductive growth and NSC levels in the stem

Methods

Results

Conclusion