Molecular Hydrogen Increases Quantitative and Qualitative Traits of Rice Grain in Field Trials

Abstract

How to use environmentally friendly technology to enhance rice field and grain quality is a challenge for the scientific community. Here, we showed that the application of molecular hydrogen in the form of hydrogen nanobubble water could increase the length, width, and thickness of brown/rough rice and white rice, as well as 1000-grain weight, compared to the irrigation with ditch water. The above results were well matched with the transcriptional profiles of representative genes related to high yield, including up-regulation of heterotrimeric G protein β-subunit gene (RGB1) for cellular proliferation, Grain size 5 (GS5) for grain width, Small grain 1 (SMG1) for grain length and width, Grain weight 8 (GW8) for grain width and weight, and down-regulation of negatively correlated gene Grain size 3 (GS3) for grain length. Meanwhile, although total starch content in white rice is not altered by HNW, the content of amylose was decreased by 31.6%, which was parallel to the changes in the transcripts of the amylose metabolism genes. In particular, cadmium accumulation in white rice was significantly reduced, reaching 52% of the control group. This phenomenon was correlated well with the differential expression of transporter genes responsible for Cd entering plants, including down-regulated Natural resistance-associated macrophage protein (Nramp5), Heavy metal transporting ATPase (HMA2 and HMA3), and Iron-regulated transporters (IRT1), and for decreasing Cd accumulation in grain, including down-regulated Low cadmium (LCD). This study clearly showed that the application of molecular hydrogen might be used as an effective approach to increase field and grain quality of rice.

Molecular Hydrogen Improves Rice Storage Quality via Alleviating Lipid Deterioration and Maintaining Nutritional Values

“…At the same time, according to the previous study [ 39 ], the above results might be not correlated with the taste of rice. However, we found that HNW could significantly reduce the amylose/starch ratio of stored rice compared to the control, and this is consistent with our previous research [ 22 ] ( Figure S2 ), which was beneficial for improving the taste quality of stored rice [ 40 ]. In order to understand the effects of molecular hydrogen on the taste quality of stored rice, further exploration is required.…”

“…Therefore, the possibility that molecular hydrogen could decrease bacterial growth (or their specific enzymatic activities) in rice grain during storage could not be easily ruled out, and the corresponding mechanisms require further study. Of note, in our previous study, after preharvest HNW application, the white rice was plumper and glossier compared with the control [ 22 ]. In this study, preharvest HNW application could decrease rice off-flavor generation during storage.…”

“…Combining the results of the amino acid contents ( Figure 5 ) with our previous discovery that molecular hydrogen application at preharvest could improve element content, such as iron, magnesium, etc. [ 22 ], we further propose that molecular hydrogen could improve nutritional values, which is beneficial for human health.…”

“…We discovered in our previous research that molecular hydrogen improves the qualitative and quantitative traits of rice grain [ 22 ]. On this basis, it is necessary to assess the effects of molecular hydrogen for the rice postharvest stage in the food supply chain.…”

Editorial for Special Issue: “Production and Role of Molecular Hydrogen in Plants”

“…Cheng et al [ 23 ] have taken H 2 applications out into the field, with trials of whether such treatments will improve rice. They too use HNW, comparing it to ditch water.…”