Light Absorption and Partitioning in Relation to Nitrogen Content in 'Fuji' Apple Leaves

Bench-grafted 'Fuji' apple ( Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.) trees on Malling 26 (M.26) rootstocks were fertigated for 6 weeks with N concentrations ranging from 0 to 20 m M. These treatments produced levels of leaf N ranging from 0.9 to 4.3 g·m -2 . Over this range, leaf absorptance increased curvilinearly from 74.8% to 92.5%. The light saturation point for CO2 assimilation expressed on the basis of absorbed light increased linearly at first with increasing leaf N, then reached a plateau at a leaf N content of ≈3 g·m -2 . Under high light conditions (photosynthetic photon flux of 1500 μmol·m -2 ·s -1 ), the amount of absorbed light in excess of that required to saturate CO 2 assimilation decreased with increasing leaf N. Chlorophyll fluorescence measurements revealed that the maximum photosystem II (PSII) efficiency of dark-adapted leaves was relatively constant over the leaf N range, except for a slight decrease at the lower end. As leaf N increased, nonphotochemical quenching declined under high light, and there was an increase in the efficiency with which the absorbed photons were delivered to open PSII centers. The photochemical quenching coefficient remained high except for a decrease at the lower end of the leaf N range. Actual PSII efficiency increased curvilinearly with increasing leaf N, and was highly correlated with light-saturated CO 2 assimilation. The fraction of absorbed light potentially going into singlet oxygen formation was estimated to be ≈10%, regardless of leaf N status. It was concluded that there was more excess absorbed light in low N leaves than in high N leaves under high light conditions. Nonphotochemical quenching was enhanced with decreasing leaf N to reduce both the PSII efficiency and the probability of damage from photooxidation by excess absorbed light.

[1]  W. W. Adams,et al.  Close relationship between the state of the xanthophyll cycle pigments and photosystem II efficiency during recovery from winter stress , 1996 .

[2]  B. Demmig‐Adams,et al.  The xanthophyll cycle and sustained thermal energy dissipation activity in Vinca minor and Euonymus kiautschovicus in winter , 1995 .

[3]  D. Arnon.  COPPER ENZYMES IN ISOLATED CHLOROPLASTS. POLYPHENOLOXIDASE IN BETA VULGARIS. , 1949, Plant physiology.

[4]  J. Morton,et al.  Effects of Nitrogen on the Photosynthetic Apparatus of Clematis vitalba Grown at Several Irradiances , 1997 .

[5]  J. Briantais,et al.  The relationship between the quantum yield of photosynthetic electron transport and quenching of chlorophyll fluorescence , 1989 .

[6]  G. Edwards,et al.  Relationship between photosystem II activity and CO2 fixation in leaves , 1992 .

[7]  Govindjee,et al.  Xanthophyll cycle-dependent quenching of photosystem II chlorophyll a fluorescence: formation of a quenching complex with a short fluorescence lifetime. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[8]  J. Snel,et al.  The use of chlorophyll fluorescence nomenclature in plant stress physiology , 1990, Photosynthesis Research.

[9]  T. Sharkey.  Feedback limitation of photosynthesis and the physiological role of ribulose bisphosphate carboxylase carbamylation , 1990 .

[10]  G. Schuman,et al.  Automated Total Nitrogen Analysis of Soil and Plant Samples1 , 1973 .

[11]  P. Horton,et al.  REGULATION OF LIGHT HARVESTING IN GREEN PLANTS. , 1996, Annual review of plant physiology and plant molecular biology.

[12]  Lailiang Cheng,et al.  Photosynthesis in relation to nitrogen in apple (Malus domestica Borkh.) leaves , 1999 .

[13]  W. W. Adams,et al.  Enhanced Employment of the Xanthophyll Cycle and Thermal Energy Dissipation in Spinach Exposed to High Light and N Stress , 1997, Plant physiology.

[14]  A. Hoehn,et al.  Chilling Temperatures and the Xanthophyll cycle. A Comparison of Warm-grown and Overwintering Spinach , 1995 .

[15]  W. Bilger,et al.  Chlorophyll fluorescence as a nonintrusive indicator for rapid assessment of in vivo photosynthesis , 1994 .

[16]  David Baker,et al.  Using chlorophyll fluorescence to assess the fraction of absorbed light allocated to thermal dissipa , 2008 .

[17]  T. Lamaze,et al.  Adaptation of the Photosynthetic Apparatus in Maize Leaves as a Result of Nitrogen Limitation : Relationships between Electron Transport and Carbon Assimilation. , 1990, Plant physiology.

[18]  W. W. Adams,et al.  Carotenoid composition and down regulation of photosystem II in three conifer species during the winter , 1994 .

[19]  J. R. Evans.  Developmental Constraints on Photosynthesis: Effects of Light and Nutrition , 1996 .

[20]  A. Gilmore,et al.  Mechanistic aspects of xanthophyll cycle‐dependent photoprotection in higher plant chloroplasts and leaves , 1997 .

[21]  G. Krause,et al.  In situ study of photoinhibition of photosynthesis and xanthophyll cycle activity in plants growing in natural gaps of the tropical forest , 1998 .

[22]  C. Hampson,et al.  Photosynthetic Rate, Flowering, and Yield Component Alteration in Hazelnut in Response to Different Light Environments , 1996 .

[23]  K. Asada.  Radical Production and Scavenging in the Chloroplasts , 1996 .

[24]  A. Verhoeven,et al.  'Photoinhibition' During Winter Stress: Involvement of Sustained Xanthophyll Cycle-Dependent Energy Dissipation , 1995 .

[25]  D. Koller.  Light‐driven leaf movements* , 1990 .

[26]  B. Logan,et al.  Xanthophyll cycle-dependent energy dissipation and flexible photosystem II efficiency in plants acclimated to light stress , 1995 .