A Simple Method for Quantitative Estimation of Rhizosphere pH along Root Axes through Visualization

Rao, Theertham P.; Yano, Katsuya; Yamauchi, Akira; Tatsumi, Jiro

doi:10.1626/pps.3.101

Cited by 7 publications

(4 citation statements)

References 26 publications

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“…Changes of rhizosphere pH along the taproot axis were ®rst visualized and then quanti®ed into proton¯uxes according to Rao et al (2000b) by using pH indicator agar gel and image analysis. A 3-mm thick agar gel (9´0 g l ±1 ) ®lm containing bromocresol purple (0´1 g l ±1 ) and nutrients (details are given in each experiment) was prepared.…”

Section: Visualization and Quanti®cation Of Ph Changesmentioning

confidence: 99%

“…The digitized images were processed with image analysis to identify the pH gradient in the rhizosphere using a previously established pH versus colour density calibration. Then, the pH changes were transformed into apparent proton¯uxes to quantify the degree of acidi®cation/ alkalization along the root axis (Rao et al, 2000b). The proton¯ux was calculated based on the difference between measured and initial pH (Versel and Pilet, 1986).…”

Section: Visualization and Quanti®cation Of Ph Changesmentioning

confidence: 99%

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Regulation of Rhizosphere Acidification by Photosynthetic Activity in Cowpea (Vigna unguiculata L. Walp.) Seedlings

Rao

Yano²,

Iijima³

et al. 2002

Annals of Botany

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In contrast to cereals or other crops, legumes are known to acidify the rhizosphere even when supplied with nitrates. This phenomenon has been attributed to N2 fixation allowing excess uptake of cations over anions; however, as we have found previously, the exposure of the shoot to illumination can cause rhizosphere acidification in the absence of N2 fixation in cowpea (Vigna unguiculata L. Walp). In this study, we examined whether the light-induced acidification can relate to photosynthetic activity and corresponding alterations in cation-anion uptake ratios. The changes of rhizosphere pH along the root axis were visualized using a pH indicator agar gel. The intensity of pH changes (alkalization/acidification) in the rhizosphere was expressed in proton fluxes, which were obtained by processing the images of the pH indicator agar gel. The uptake of cations and anions was measured in nutrient solution. The rhizosphere was alkalinized in the dark but acidified with exposure of the shoots to light. The extent of light-induced acidification was increased with leaf size and intensity of illumination on the shoot, and completely stopped with the application of photosynthesis inhibitor. Although the uptake of cations was significantly lower than that of anions, the rhizosphere was acidified by light exposure. Proton pump inhibitors N,N'-dicyclohexyl carbodimide and vanadate could not stop the light-induced acidification. The results indicate that light-induced acidification in cowpea seedlings is regulated by photosynthetic activity, but is not due to excess uptake of cations.

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Section: Visualization and Quanti®cation Of Ph Changesmentioning

confidence: 99%

Section: Visualization and Quanti®cation Of Ph Changesmentioning

confidence: 99%

Regulation of Rhizosphere Acidification by Photosynthetic Activity in Cowpea (Vigna unguiculata L. Walp.) Seedlings

Rao

Yano²,

Iijima³

et al. 2002

Annals of Botany

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show abstract

“…The determination of rhizosphere acidi cation follows the method of Rao et al (2000a;. The agar-gel (containing 0.1 g L − 1 bromocresol purple indicator and 9.0 g L − 1 agar) was prepared with a pH of 6.2 at 13 × 13 cm square petri dish (about 0.4 cm thick).…”

Section: Rhizosphere Acidi Cationmentioning

confidence: 99%

Soybean triggers morphological responses of tomato roots by modifying P capture under low P condition

Zhang,

Yan,

Zhou

et al. 2023

Preprint

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Background and aims Plant roots alter morphology to respond nutrients and neighbors, but whether neighbors influence the root architecture by modifying the availability of N and P nutrients is still unclear. Here we aimed to screen intercropping plants that cause changes in tomato root architecture and explore the role of nutrients. Methods We carried out the experiments of tomato-neighbor interactions to survey root morphological responses of target tomato seedlings. Then we investigated root plastic response to intercropping soybean under different P (0, 100, 200 mg P205 kg− 1 soil) or N (0, 100, 200 mg N kg− 1 soil) levels. In addition, we investigated the effects and physiological mechanisms of intercropping soybean on P capture of tomato seedlings. Results The intercropping soybean changed the horizontal symmetry of tomato roots, the dry weight and total root length of tomato roots in the ‘Toword’ region were significantly higher than those in the ‘Away’ region, while other intercropping plants did not. P rather than N levels, significantly affected the phenotypic plasticity of tomato roots in soybean intercropping systems. Under phosphorus deficiency condition, tomato roots showed a tendency to soybean. This phenomenon disappeared when the P supply increased in the soil. Under low P condition, intercropped soybean significantly increased the P concentration of tomato plants and the available P content of rhizosphere soil. Compared with tomatoes, soybean roots secreted more acid phosphatase, protons and organic acids. Conclusions Soybean triggers morphological responses of tomato roots through modifying P capture mediated by root exudates under low P condition.

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“…The difference in rhizosphere acidi cation between rice seedlings and water spinach seedlings was studied visually by quantifying the proton e ux of roots (Rao et al 2000). At rst, 0.5 g of agar and 0.5 mL of 0.6% bromocresol purple indicator were added into a 50 mL medium containing 50 mg•L − 1 NH 4 + (1000 mL H 2 O + 183 mg (NH 4 ) 2 SO 4 +136 mg CaSO 4 ).…”

Section: Incubation Study 2 (Visualization Of Rhizosphere Acidi Cation)mentioning

confidence: 99%

Plant-mediated rhizospheric interactions in rice-water spinach intercropping enhance Si uptake by rice

Ning

Wang

et al. 2021

Preprint

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Aims Although biodiversity utilization in paddy fields has increased in recent years, silicon (Si) nutrition of rice in intercropping systems is poorly understood. On the basis of our previous study, the present research focused on deciphering the underlying mechanisms involved in rice and water spinach intercropping, which enhance Si uptake by rice.Methods We carried out a series of experiments including field, greenhouse, and incubation experiments to explore the underlying mechanisms.Results The field trials showed that rice-water spinach intercropping with different row ratios can increase Si concentration by 9.8%-52.6% and Si absorption by 34.7%-127.8% in rice leaves at ripening stage compared to rice monoculture. The pot trials further indicated that intercropping can promote rice to increase Si concentration in Si-deficient soil, with an increase of 35.9% in stems and 29.7% in leaves, and intercropping significantly increased soil water-soluble Si content by 168.1% compared to rice monoculture. Further research indicated that there was an interaction between rice roots and water spinach roots under intercropping conditions, which not only induced the up-regulated expression of Si transporter genes in rice roots (OsLsi1, OsLsi2) and stems (OsLsi6), but also stimulated rice roots to secrete more organic acids to increase Si availability in the soil. Moreover, water spinach root exudates helped the mobilization of Si in soil through proton efflux of roots. Conclusions Rice-water spinach intercropping can greatly enhance Si absorption of rice through several beneficial ways, which will have important practical significance for sustainable rice production, especially in Si-deficient soils.

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A Simple Method for Quantitative Estimation of Rhizosphere pH along Root Axes through Visualization

Cited by 7 publications

References 26 publications

Regulation of Rhizosphere Acidification by Photosynthetic Activity in Cowpea (Vigna unguiculata L. Walp.) Seedlings

Regulation of Rhizosphere Acidification by Photosynthetic Activity in Cowpea (Vigna unguiculata L. Walp.) Seedlings

Soybean triggers morphological responses of tomato roots by modifying P capture under low P condition

Plant-mediated rhizospheric interactions in rice-water spinach intercropping enhance Si uptake by rice

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