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Effects of nitrogen nutrition and root medium water potential on growth, nitrogen uptake and osmotic adjustment of rice
Author(s) -
Yambao E. B.,
O'Toole J. C.
Publication year - 1984
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1984.tb04919.x
Subject(s) - osmotic pressure , nitrogen , shoot , nutrient , turgor pressure , chemistry , dry matter , dry weight , agronomy , oryza sativa , horticulture , osmotic shock , botany , biology , biochemistry , organic chemistry , gene
The effects of nitrogen (N) nutrition on growth, N uptake and leaf osmotic potential of rice plants ( Oryza sativa L. ev. IR 36) during simulated water stress were determined. Twenty‐one‐day‐old seedlings in high (28.6 × 10 −4 M ) and low (7.14 × 10 4 M ) N levels were exposed to decreased nutrient solution water potentials by addition of polyethylene glycol 6000. The roots were separated from the solution by a semi‐permeable membrane. Nutrient solution water potential was −0.6 × 10 5 Pa and was lowered stepwise to −1 × 10 5 , −2 × 10 5 , −4 × 10 5 and −6 × 10 5 Pa at 2‐day intervals. Plant height, leaf area and shoot dry weight of high and low nitrogen plants were reduced by lower osmotic potentials of the root medium. Osmotic stress caused greater shoot growth reduction in high N than in low N plants. Stressed and unstressed plants in 7.14 × 10 4 M N had more root dry matter than the corresponding plants in 28.6 × 10 4 M N. Dawn leaf water potential of stressed plants was 1 × 10 5 to 5.5 × 10 5 Pa lower than nutrient solution water potential. Nitrogen‐deficient water‐stressed plants, however, maintained higher dawn leaf water potential than high nitrogen water‐stressed plants. It is suggested that this was due to higher root‐to‐shoot ratios of N deficient plants. The osmotic potentials of leaves at full turgor for control plants were about 1.3 × 10 5 Pa higher in 7.14 × 10 −4 M than in 28.6 × 10 −4 M N and osmotic adjustment of 2.6 × 10 5 and 4.3 × 10 5 Pa was obtained in low and high N plants, respectively. The nitrogen status of plants, therefore, affected the ability of the rice plant to adjust osmotically during water stress. Plant water stress decreased transpiration and total N content in shoots of both N treatments. Reduced shoot growth as a result of water stress caused the decrease in amount of water transpired. Transpiration and N uptake were significantly correlated. Our results show that nitrogen content is reduced in water‐stressed plants by the integrated effects of plant water stress per se on accumulation of dry matter and transpiring leaf area as well as the often cited changes in soil physical properties of a drying root medium.