Ammonium concentration in solution affects chlorophyll meter readings in tomato leaves

Abstract Combinations of NH4‐N:NO3‐N usually result in higher tomato (Lycopersicon esculentum Mill.) yields than when either form of nitrogen (N) was used alone. Leaf chlorophyll content is closely related to leaf N content, but the effect of the NH4‐N:NO3‐N ratio on leaf greenness was not clear. The objective of this study was to determine the influence of NH4‐N:NO3‐N ratios on chlorophyll meter (SPAD) readings, and evaluate the meter as a N status estimator and tomato yield predictor in greenhouse production systems. Fruit yield and SPAD readings increased as the amount of NH4‐N in solution increased up to 25%, while higher ratios of NH4‐N resulted in a decline in both. The N concentration in tomato leaves increased as concentration of NH4‐N in solution increased. Fruit yield increased as chlorophyll readings increased. SPAD readings, total N in leaves, fresh weight of shoots, and fruit yield all showed a quadratic response to NH4‐N, reaching a peak at 25 or 50% of N as NH4‐N. SPAD readings taken at the...

[1]  Yuncong C. Li,et al.  A Rapid Nondestructive Technique to Predict Leaf Nitrogen Status of Grapefruit Tree with Various Nitrogen Fertilization Practices , 1998 .

[2]  Jr. Jones,et al.  Hydroponics: A Practical Guide for the Soilless Grower , 1997 .

[3]  P. Santamaria,et al.  Producing Nitrate-free Endive Heads: Effect of Nitrogen Form on Growth, Yield, and Ion Composition of Endive , 1997 .

[4]  C. W. Wood,et al.  Chlorophyll meter predicts nitrogen status of tall fescue , 1996 .

[5]  J. Wraith,et al.  Correlation of leaf chlorophyll readings and stem nitrate concentrations in peppermint , 1995 .

[6]  J. Sieczka,et al.  Field chlorophyll measurements to assess the nitrogen status of potato varieties , 1994 .

[7]  S. Inanaga,et al.  Response of sand‐grown tomato supplied with varying ratios of nitrate/ammonium to constant and variable root temperatures , 1994 .

[8]  E. Simonne,et al.  Turnip growth, leaf yield, and leaf nutrient composition responses to nitrogen forms , 1993 .

[9]  C. W. Wood,et al.  Relationships between chlorophyll meter readings and leaf chlorophyll concentration, N status, and crop yield: A review 1 , 1993 .

[10]  E. Simonne,et al.  Ammonium reduces growth, fruit yield and fruit quality of watermelon , 1992 .

[11]  C. W. Wood,et al.  Field chlorophyll measurements for evaluation of corn nitrogen status 1 , 1992 .

[12]  Hector R. Marti,et al.  Nutrient uptake and yield of sweet pepper as affected by stage of development and N form , 1991 .

[13]  U. Kafkafi.  Root temperature, concentration and the ratio NO3−/NH4+ effect on plant development , 1990 .

[14]  T. Yoneyama,et al.  Measurement of Leaf Color Scores and Its Implication to Nitrogen Nutrition of Rice Plants , 1989 .

[15]  R R Coltman,et al.  Yields of Greenhouse Tomatoes Managed to Maintain Specific Petiole Sap Nitrate Levels , 1988, HortScience.

[16]  B. Shelp.  Plant Characteristics and Nutrient Composition and Mobility of Broccoli (Brassica oleracea var. italica) Supplied with NH4+, NO3⊟ or NH4NO3 , 1987 .

[17]  J. Morot-Gaudry,et al.  Nitrate and ammonium nutrition in plants , 1987 .

[18]  J. Jones,et al.  The Influence of Nitrate:Ammonium Ratios on Growth, Fruit Development, and Element Concentration in ‘Floradel’ Tomato Plants , 1986, Journal of the American Society for Horticultural Science.

[19]  A. A. Steiner.  The universal nutrient solution , 1984 .

[20]  W. Pill,et al.  Effects of Preplant Phosphorus Fertilization Rate and of Nitrate and Ammonium Liquid Feeds on Tomato Grown in Peat–Vermiculite , 1983, Journal of the American Society for Horticultural Science.

[21]  S. Yoshida.  Fundamentals of rice crop science , 1981 .

[22]  L. Mugwira,et al.  Ammonium‐N and Nitrate‐N Effects on the Growth and Mineral Compositions of Triticale, Wheat, and Rye1 , 1981 .

[23]  R. Ganmore-Neumann,et al.  Root Temperature and Percentage NO3−/NH4+ Effect on Tomato Development II. Nutrients Composition of Tomato Plants1 , 1980 .

[24]  G. Seber,et al.  Linear Regression Analysis , 1980 .

[25]  E. A. Kirkby,et al.  Ionic balance in different tissues of the tomato plant in relation to nitrate, urea, or ammonium nutrition. , 1967, Plant physiology.