Effects of low ozone exposure of spring wheat on net CO2 uptake, Rubisco, leaf senescence and grain filling

Crassulacean acid metabolism (CAM) was observed in three species of tropical ferns, the epiphytes Microsorium punctatum and Polypodium crassifolium and the lithophyte Platycerium veitchii. Polypodium crassifolium and P. veitchii exhibited characteristics of weak CAM. Although no net nocturnal CO2 uptake was observed, the presence of CAM was inferred from nocturnal increases in titratable acidity of 4.7 and 4.1 µequiv (g fr wt)–1 respectively, a reduction in the rates of net CO2 evolution during the first half of the dark period, and the presence of a CAM-like decrease in net CO2 uptake during the early light period. In M. punctatum net CO2 uptake during the first half of the dark period was accompanied by an increase in titratable acidity of 39.2 µequiv (g fr wt)–1 and a pronounced reduction in net CO2 uptake during the early light period. When water was withheld from P. crassifolium and M. punctatum, net CO2 uptake during the light was reduced markedly but there was no change in the extent or patterns of CO2 exhange in the dark. As a consequence, the proportion of carbon gained due to CO2 fixation in the dark increased from 2.8 and 10% to 63.5 and 49.3%, respectively (100% being net CO2 uptake during the light plus the estimated CO2 uptake during the dark). After 9 days without added water, dark CO2 uptake was responsible for the maintenance of a net 24 h carbon gain in P. crassifolium. Platycerium veitchii, P. crassifolium and M. punctatum exhibited carbon isotope ratios of between –25.9 and –22.6‰ indicating that carbon isotope ratios may not, by themselves, be sufficient for the identification of weak CAM. We suggest that CAM may be more prevalent in tropical epiphytic and lithophytic ferns than currently envisaged.

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Evaluation of Spring Wheat Genotypes (Triticum Aestivum L.) for Heat Stress Tolerance Using Different Stress Tolerance Indices

Cercetari Agronomice in Moldova ◽

10.1515/cerce-2015-0004 ◽

2015 ◽

Vol 47 (4) ◽

pp. 49-63 ◽

Cited By ~ 5

Author(s):

A.A. Khan ◽

M.R. Kabir

Keyword(s):

Heat Stress ◽

Grain Yield ◽

Stress Tolerance ◽

Spring Wheat ◽

Grain Filling ◽

Filling Rate ◽

Wheat Genotypes ◽

Grain Filling Rate ◽

Heat Stress Tolerance ◽

Late Sowing

Abstract Twenty five spring wheat genotypes were evaluated for terminal heat stress tolerance in field environments in the Agro Ecological Zone-11 of Bangladesh, during 2009-2010 cropping season. The experiments were conducted at Wheat Research Centre, Bangladesh Agricultural Research Institute, using randomized block design with three replicates under non-stress (optimum sowing) and stress (late sowing) conditions. Seven selection indices for stress tolerance including mean productivity (MP), geometric mean productivity (GMP), tolerance (TOL), yield index (YI), yield stability index (YSI), stress tolerance index (STI) and stress susceptibility index (SSI) were calculated based on grain yield of wheat under optimum and late sowing conditions. The results revealed significant variations due to genotypes for all characters in two sowing conditions. Principal component analysis revealed that the first PCA explained 0.64 of the variation with MP, GMP, YI and STI. Using MP, GMP, YI and STI, the genotypes G-05 and G-22 were found to be the best genotypes with relatively high yield and suitable for both optimum and late heat stressed conditions. The indices SSI, YSI and TOL could be useful parameters in discriminating the tolerant genotypes (G-12, G-13, and G-14) that might be recommended for heat stressed conditions. It is also concluded from the present studies that biomass, grain filling rate and spikes number m-2 are suitable for selecting the best genotypes under optimum and late sowing conditions because these parameters are highly correlated with MP, GMP, YI and STI. However, high ground cover with long pre heading stage and having high grain filling rate would made a genotype tolerant to late heat to attain a high grain yield in wheat.

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Cloud cover limits net CO2 uptake and growth of a rainforest tree during tropical rainy seasons

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0133045100 ◽

2003 ◽

Vol 100 (2) ◽

pp. 572-576 ◽

Cited By ~ 253

Author(s):

E. A. Graham ◽

S. S. Mulkey ◽

K. Kitajima ◽

N. G. Phillips ◽

S. J. Wright

Keyword(s):

Cloud Cover ◽

Co2 Uptake ◽

Net Co2 Uptake

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Spring photosynthetic onset and net CO2 uptake in Alaska triggered by landscape thawing

Global Change Biology ◽

10.1111/gcb.14283 ◽

2018 ◽

Vol 24 (8) ◽

pp. 3416-3435 ◽

Cited By ~ 14

Author(s):

Nicholas C. Parazoo ◽

Almut Arneth ◽

Thomas A. M. Pugh ◽

Ben Smith ◽

Nicholas Steiner ◽

...

Keyword(s):

Co2 Uptake ◽

Net Co2 Uptake

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Environmental response of spring wheat in the south-western Australian cereal belt

Australian Journal of Agricultural Research ◽

10.1071/ar9870655 ◽

1987 ◽

Vol 38 (4) ◽

pp. 655 ◽

Cited By ~ 21

Author(s):

KG Rickert ◽

RH Sedgley ◽

WR Stern

Keyword(s):

Water Use ◽

Spring Wheat ◽

Critical Evaluation ◽

Grain Filling ◽

High Ratio ◽

Soil Types ◽

Environmental Response ◽

Total Water ◽

Eastern Australia ◽

Dry Conditions

The performance of the spring wheat cultivar Gamenya, the leading cultivar in Western Australia since 1968, was studied to identify key aspects of its response to the environment under typically dry conditions on two contrasting soil types: a heavy clay loam and a light loamy sand overlying clay in the Merredin region.In the rain-fed treatments the total water use was similar on both soils and was of the order of 240 mm. On the heavy-textured soil at high nitrogen, the foliage canopy developed more rapidly than on the light soil, resulting in earlier soil water depletion and haying off. Water use efficiencies of about 10 kg grain ha-1 per mm of water were similar to those reported for winter rainfall areas in south-eastern Australia. This suggests a greater degree of buffering against spring drought than is indicated by the high ratio of pre-anthesis to post-anthesis water use (3-4.7:l) relative to values of 2-2.7:l in other parts of the Australian wheatbelt. Data on the partitioning of dry matter indicated that this buffering of the harsh spring conditions at Merredin may be due to a greater contribution of assimilates from pre-anthesis storage, to grain filling. In dry environments, further critical evaluation is needed of the role of stored assimilates in grain formation.Faster canopy closure on the heavy soil resulted from a higher density of shoots and possibly larger leaves. This led to the suggestion that on heavier, more fertile soils, an ideotype with restricted tillering, may be higher yielding. By the end of the season ear bearing shoot densities and total water use were the same on both soil types, thus masking earlier important differences.

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Mutation of ONAC096 Enhances Grain Yield by Increasing Panicle Number and Delaying Leaf Senescence during Grain Filling in Rice

International Journal of Molecular Sciences ◽

10.3390/ijms20205241 ◽

2019 ◽

Vol 20 (20) ◽

pp. 5241 ◽

Cited By ~ 6

Author(s):

Kiyoon Kang ◽

Yejin Shim ◽

Eunji Gi ◽

Gynheung An ◽

Nam-Chon Paek

Keyword(s):

Grain Yield ◽

Leaf Senescence ◽

Grain Filling ◽

Pcr Analysis ◽

Cytokinin Oxidase ◽

Panicle Number ◽

Reverse Transcription Quantitative Pcr ◽

Dna Insertion ◽

Upregulated Genes ◽

Insertion Mutants

Exploring genetic methods to improve yield in grain crops such as rice (Oryza sativa) is essential to help meet the needs of the increasing population. Here, we report that rice ONAC096 affects grain yield by regulating leaf senescence and panicle number. ONAC096 expression increased rapidly in rice leaves upon the initiation of aging- and dark-induced senescence. Two independent T-DNA insertion mutants (onac096-1 and onac096-2) with downregulated ONAC096 expression retained their green leaf color during natural senescence in the field, thus extending their photosynthetic capacity. Reverse-transcription quantitative PCR analysis showed that ONAC096 upregulated genes controlling chlorophyll degradation and leaf senescence. Repressed OsCKX2 (encoding cytokinin oxidase/dehydrogenase) expression in the onac096 mutants led to a 15% increase in panicle number without affecting grain weight or fertility. ONAC096 mediates abscisic acid (ABA)-induced leaf senescence by upregulating the ABA signaling genes ABA INSENSITIVE5 and ENHANCED EM LEVEL. The onac096 mutants showed a 16% increase in grain yield, highlighting the potential for using this gene to increase grain production.

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