Chill-induced inhibition of photosynthesis: genotypic variation within Cucumis sativus.
Cucumber is generally a thermophilic species; however, cultivars have been selected for higher yield during winter cultivation in unheated glasshouses in temperate regions. We tested whether photosynthesis in these varieties had greater chilling tolerance. There was no difference in the instantaneous reduction of photosynthesis at low temperature between four winter glasshouse and four summer field cultivars. After 5 d of 10 degrees C and 100 micro mol m(-2) s(-1) photon flux density, the four field cultivars had a sustained depression of photosynthesis after returning to clement conditions. This inhibition was associated with reduced rates of CO(2) fixation and photosystem II (PSII) electron transport in the light, but not with sustained PSII photoinhibition. However, photosynthesis in the glasshouse genotypes was nearly identical to the pre-chill rates. Chill impacts on light-adapted chlorophyll fluorescence parameters, such as the quantum yield of PSII electron transport (phi(PSII)), correlated well with overall photosynthesis. This demonstrates the potential for using these fast and non-invasive techniques to screen for chill-tolerant genotypes, with the potential to further improve winter cucumber yield in unheated glasshouses.
Yu
Jing-Quan
JQ
Department of Horticulture, Huajiachi Campus of Zhejiang University, Kaixuan Road 268, Hangzhou, P. R. China 310029. yu@mail.hz.zj.cn
Zhou
Yan-Hong
YH
Huang
Li-Feng
LF
Allen
Damian J
DJ
D000064:Acclimatization / Q000235:genetics* / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism / Q000528:radiation effects; D018553:Cucumis sativus / Q000235:genetics* / Q000502:physiology; D004579:Electron Transport / Q000502:physiology / Q000528:radiation effects; D005838:Genotype; D008027:Light; D045342:Light-Harvesting Protein Complexes; D010788:Photosynthesis / Q000235:genetics* / Q000502:physiology; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism / Q000528:radiation effects; D045332:Photosystem II Protein Complex; D013696:Temperature
D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D002245:Carbon Dioxide