Pedosphere 19(3): 323--330, 2009
ISSN 1002-0160/CN 32-1315/P
©2009 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Growth and phosphorus uptake of oat (Avena nuda L.) as affected by mineral nitrogen forms supplied in hydroponics and soil culture |
FAN Ming-Shou1, LI Zhen1, WANG Feng-Mei1 and ZHANG Jian-Hua1,2 |
1 College of Agronomy, Inner Mongolia Agricultural University, Hohhot, Inner Mongolia 010019 (China);
2 Department of Biology, Hong Kong Baptist University, Hong Kong (China) |
| ABSTRACT |
| Plants show different growth responses to N sources supplied with either NH4+ or NO3-. The uptake of different N sources also affects the rhizosphere pH and therefore the bioavailability of soil phosphorus, particularly in alkaline soils. The plant growth, P uptake, and P availability in the rhizosphere of oat (Avena nuda L.) grown in hydroponics and in soil culture were investigated under supply with sole NH4+-N, sole NO3--N, or a combination. Sole NO3--fed oat plants accumulated more biomass than sole NH4+-fed ones. The highest biomass accumulation was observed when N was suppliedw ith both NH4+-N and NO3--N. Growth of the plant root increased with the proportion of NO3- in the cultural medium. Better root growth and higher root/shoot ratio were consistently observed in NO3--fed plants. However, root vigor was the highest when N was supplied with NO3-+NH4+. NH4+ supply reduced the rhizosphere pH but did not affect P uptake by plants grown in soils with CaHPO4 added as P source. No P deficiency was observed, and plant P concentrations were generally above 2 g kg-1. P uptake was increased when N was supplied partly or solely as NO3--N, similarly as biomass accumulation. The results suggested that oat was an NO3--preferring plant, and NO3--N was essential for plant growth and the maintenance of root absorption capacity. N supply with NH4+-N did not improve P nutrition, which was most likely due to the absence of P deficiency. |
| Key Words: alkaline soils, nitrogen nutrition, oat (Avena nuda L.), P uptake, rhizosphere pH |
| Citation: Fan, M. S., Li, Z., Wang, F. M. and Zhang, J. H. 2009. Growth and phosphorus uptake of oat (Avena nuda L.) as affected by mineral nitrogen forms supplied in hydroponics and soil culture. Pedosphere. 19(3): 323-330. |
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