Bacillus Pumilus Strain TUAT-1 and Nitrogen Application in Nursery Phase Promote Growth of Rice Plants under Field Conditions

Khin Win,Aung Oo,Tadashi Yokoyama,Naoko Ohkama-Ohtsu

doi:10.3390/agronomy8100216

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https://doi.org/10.3390/agronomy8100216

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Abstract

The aims of this study were to boost growth attributes, yield, and nutrient uptake of rice in paddy fields using a combination of Bacillus pumilus strain TUAT-1 biofertilizer and different nitrogen (N) application rates in nursery boxes. Bacillus pumilus strain TUAT-1 was applied as an inoculant biofertilizer in conjunction with different rates of N fertilizer to rice seedlings in a nursery. Plant growth and yield parameters were evaluated at two stages: in 21-day-old nursery seedlings and in mature rice plants growing in a paddy field. Inoculation with TUAT-1 significantly increased the seedling growth and root morphology of 21-day-old nursery seedlings. There was a marked increase in chlorophyll content, plant height, number of tillers, and tiller biomass of rice plants with the use of TUAT-1 and N fertilizers alone, and their combinations, at the maximum tillering stage in the field. The combination of TUAT-1 and 100% N (farmer recommended rate of N) resulted in the greatest tiller number and biomass at the maximum tillering stage, and positively affected other growth attributes and yield. The growth and yield were similar in the TUAT-1 + 50% N and 100% N (uninoculated) treatments, because TUAT-1 promoted root development, which increased nutrient uptake from the soil. These results suggest that the B. pumilus strain TUAT-1 has a potential to enhance the nutritional uptake of rice by promoting the growth and development of roots.

Highlights

Rice (Oryza sativa L.) is considered as one of the world’s most important staple foods and is the key to food security, especially under the threats of climate change in the coming decades [1]
The TUAT-1 inoculation and N fertilizer interactions were significant with respect to total root length
We suggested that the nursery applications of N fertilizer at appropriate levels with TUAT-1 biofertilizer in this field study may have masked our ability to observe significant growth impacts on rice grain yields

Summary

Introduction

Rice (Oryza sativa L.) is considered as one of the world’s most important staple foods and is the key to food security, especially under the threats of climate change in the coming decades [1]. The global rice cultivation area in 2015/2016 approached 158.8 million hectares, and total global rice production amounted to 711.24 million metric tons [2]. Nitrogen (N) fertilizers are used extensively in rice cultivation to meet the growth demands of the crop. Excessive use of chemical fertilizers, in recent decades, has led to soil toxicity by contamination with toxic heavy metals, which adversely affect the health of rice plants [3]. Inoculating rice plants with plant growth promoting rhizobacteria (PGPR).

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