e-journal

Photosynthesis and growth in diverse willow genotypes

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During a study of the contribution of photosynthetic traits to biomass yield
among 11 diverse species of willow, the light and CO 2 dependence of photosynthesis
were found to differ, with absolute rates at ambient and saturating
CO 2 , together with maximum rates of Rubsico-limited and electron-transportlimited
photosynthesis ( V cmax and J , respectively) varying by factors in excess of
2 between the extremes of performance. In spite of this, the ratio, J / V cmax –
indicative of the relative investment of resource into Ru BP regeneration and
Ru BP carboxylation – was found to fall within a narrow range (1.9–2.5) for all
genotypes over two successive years. Photosynthetic rate ( μ mol CO 2
fi xed m −2 sec −1 ) showed a strong, inverse correlation with total leaf area per
plant. Photosynthetic capacity, expressed on a leaf area basis, showed a strong,
positive correlation with yield among some of the species, but when expressed
on a whole plant basis all species indicated a positive correlation with yield.
Thus, both leaf area per plant and photosynthetic rate per unit leaf area contribute
to this relationship. The abundance and kinetic characteristics of Rubisco
play a pivotal role in determining photosynthetic rate per unit leaf area and so
were determined for the chosen willow species, in parallel with Rubisco large
subunit ( LSU ) gene sequencing. Signifi cant differences in the rate constants for
carboxylation and oxygenation as well as the affi nity for CO 2 were identifi ed,
and rationalized in terms of LSU sequence polymorphism. Those LSU sequences
with isoleucine instead of methionine at residue 309 had up to 29% higher
carboxylase rate constants. Furthermore, the A/Ci curves predicted from each
distinct set of Rubisco kinetic parameters under otherwise identical conditions
indicated substantial differences in photosynthetic performance. Thus, genetic
traits relating specifi cally to Rubisco and by implication to photosynthetic
performance were also identified.

Keywords: A/Ci , carbon isotope ratio , CO 2 assimilation , photosynthesis , Rubisco , Salix

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Informasi Detail

Judul Seri

Food and Energy Security

No. Panggil

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Penerbit

New York : John Wiley & Sons, Ltd.., 2014

Deskripsi Fisik

Food and Energy Security 2014; 3(2): 69–85

Bahasa

English

ISBN/ISSN

doi: 10.1002/fes3.47

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

2014; 3(2): 69–85

Subjek

PERTANIAN.

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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