Root Research

The Influences of high root-zone temperature on absorption of water and nitrate by tomato roots hydroponically grown in atmosphere or in solution

Yuka NAKANO, Akimasa NAKANO, Shin-ichi WATANABE, Masuyuki TAKAICHI, Ji ...

2003 Volume 12 Issue 2 Pages 35-40
Published: June 27, 2003
Released on J-STAGE: December 18, 2009

DOIhttps://doi.org/10.3117/rootres.12.35

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Tomato seedlings were grown in a Wet-sheet culture (WSC), where roots developed in the wet atmosphere, or in a Deep flow technique (DFT), where roots were submerged in the solution.
Differences in water and nitrate absorption between tomato roots in the WSC and DFT were compared at four-root temperatures; 17, 27, 33 and 45°C. Root dry weight in the WSC was larger than in the DFT, whereas whole plant weights in the both systems were equal. Water absorption rates on whole root were almost equal in the both systems at all temperature. On the other hand, nitrate absorption was greater in the WSC than the DFT at 45°C, but no significant differences were observed at other temperatures. Root respiration in the DFT showed an increase as the root temperature increased from 17°C to 33°C, but decreased at 45°C. We suggested that roots in the wet atmosphere would be more tolerant to supraoptimal temperature than those in the solution, in part because of keeping with its activity.

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Recovery of tree vigor by root pruning in Weeping-type Japanese Flowering Cherry

Masa-aki TAGA, Hiromitsu GOTO

2003 Volume 12 Issue 2 Pages 41-49
Published: June 27, 2003
Released on J-STAGE: December 18, 2009

DOIhttps://doi.org/10.3117/rootres.12.41

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In soil-amending work to recover vigor of a weakened tree, pruning of root tips is usually prohibited by the arborists. On the other hand, in tea plant cultivation, productivity is recovered by renewing the roots by pruning root tips. In the soil-amending work to recover the vigor of an extremely weakened 130-year-old Japanese weeping-type flowering cherry at Tajimi City in Gifu Prefecture, which is a natural monument, we pruned the roots. Then, we examined the emergence, branching and elongation of new roots at intervals, to determine the suitable time of root pruning and suitable thickness of root to be pruned. The tree vigor after the root pruning observed in each above-ground organ was compared with that in a successor tree, and the effectiveness of root pruning was confirmed. In addition, we found that the growth promotion of each above-ground organ by root pruning was similar to that by cytokinin.

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Germination stimulants for the seeds of root parasitic plants

Yukihiro SUGIMOTO, Koichi YONEYAMA

2003 Volume 12 Issue 2 Pages 51-56
Published: June 27, 2003
Released on J-STAGE: December 18, 2009

DOIhttps://doi.org/10.3117/rootres.12.51

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The seeds of root parasitic plants only germinate in response to specific chemicals (germination stimulants) secreted from host and some non-host roots. For these parasitic plants, which are totally dependent on a specific association with a host that provides them with nutrients and water, this system ensures that germination only occurs when suitable host roots are available in the close vicinity. Root parasitic plants cause devastating effects on their hosts, which in most cases are cereals and legumes, staple food for people in many parts of the world. This mini-review describes the germination stimulants for root parasitic plants, the importance of the stimulants in host recognition, and possible control measures against root parasitic plants using germination stimulants.

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Hydraulic conductivity and solute permeability of roots

by using root pressure probe

Naoko MIYAMOTO

2003 Volume 12 Issue 2 Pages 57-61
Published: June 27, 2003
Released on J-STAGE: December 18, 2009

DOIhttps://doi.org/10.3117/rootres.12.57

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There are many resistances to radial water flow in plant root. Water may move from root surface to xylem vessels via apoplastic pathway and cell-to-cell pathway. By using root pressure probe, some measurements suggest that water flow via apoplastic pathway is restricted at hydrophobic tissues (endodermis and exodermis) where Casparian bands and suberin lamellae are developed. However, the water flow might not be completely blocked at these tissues. The hydraulic conductivity in apoplastic pathway of rice root is lower than that of corn root. This may be one reason for lower water uptake rate by rice root system. Although rice root lacks many cortical cells because of development of aerenchyma, the influence of aerenchyma on water flow via cell-to-cell pathway might be very small. Solute permeabilities and reflection coefficients also can be measured by using root pressure probe. Rice root has lower solute permeabilities and reflection coefficients than corn root. This suggests that rice root may not discriminate solute from water strictly but permieabilities of water and solute are restricted simultaneously.

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[title in Japanese]

[in Japanese], [in Japanese]

2003 Volume 12 Issue 2 Pages 63-65
Published: June 27, 2003
Released on J-STAGE: December 18, 2009

DOIhttps://doi.org/10.3117/rootres.12.63

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[title in Japanese]

2003 Volume 12 Issue 2 Pages 69-100
Published: June 27, 2003
Released on J-STAGE: December 18, 2009

DOIhttps://doi.org/10.3117/rootres.12.69

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