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Growth, dry matter partitioning, and diurnal activities of RuBP carboxylase in citrus seedlings maintained at two levels of CO 2
Author(s) -
Koch Karen E.,
Jones Pierce H.,
Avigne Wayne T.,
Allen L. Hartwell
Publication year - 1986
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.1399-3054.1986.tb05766.x
Subject(s) - rootstock , shoot , citrus × sinensis , dry matter , rutaceae , horticulture , dry weight , biology , botany , specific leaf area , chemistry , photosynthesis , orange (colour)
The long‐term response of citrus rootstock seedlings to CO 2 enrichment was examined in Carrizo estrange ( Poncirua trifoliata (L.) Raf. x Citrus sinensis (L.) Osbeck] and Swingle citrumelo ( P. trifoliate x C. parodist Macf.]. Plaotlets 14 weeks old were transferred to outdoor controlled‐environment chambers and maintained for 5 months from Feb. 14 to July 21. During this period, new growth (cm) of citrange and citrumelo shoots at 660 μl1 −1 was 94 and 69% greater, respectively, than at 330 μ1 1 −1 . Total dry weight of both rootstock shoots had increased by over 100%. Growth of few species is affected this markedly by elevated CO 2 levels. More carbon was partitioned to above‐ground organs in CO 2 ‐enriched citrus seedlings. Stem dry matter per unit length was also 32 and 44% greater in citrange and citrumelo, respectively. Total leaf area was increased by 124% in citrange and 85% in citrumelo due to greater leaf number and size. Variations in overall relative growth rate appeared to be related to the rapid, sequential, flush‐type growth in citrus, in which an entire shoot segment with its associated leaves remains an active sink until fully expanded. RuBP carboxylase (EC 4.1.1.39) activity in leaves of recently‐expanded flushes was higher in citrumelo plants grown at 660 vs 330 μ1 1 −1 CO 2 and changed diurnally for citrange (but not citrumelo) leaves at both CO 2 levels. The results are consistent with the hypothesis that positive long‐term effects of CO 2 enrichment may be greater in species or during growth periods where sink capacity for carbon utilization is high.