title: Cotton shoot plays a major role in mediating senescence induced by potassium deficiency.
abstract: The objective of this study was to determine the roles of shoot and root in the regulation of premature leaf senescence induced by potassium (K) deficiency in cotton (Gossypium hirsutum L.). Two contrasting cultivars (CCRI41, more sensitive to K deficiency; and SCRC22, a less sensitive cultivar) were selected for self- and reciprocal-grafting, using standard grafting (one scion/one rootstock), Y grafting (two scions/one rootstock) and inverted Y grafting (one scion/two rootstocks) at the seedling stage. Standard grafting was studied in the field in 2007 and 2008. There were no obvious differences in senescence between CCRI41 and SCRC22 scions while supplied with sufficient K. However, SCRC22 scions showed significantly greater K content, SPAD values (chlorophyll content), soluble protein content and net photosynthetic rates than CCRI41 scions while grown in K deficient solution or soil, regardless of rootstock cultivars, grafting types, growth stage and growth conditions. Also, SCRC22 scions had greater yield and less variation in boll weight either between upper- and lower sympodials, or between proximal and distal fruit positions from the main stem in the field under K deficiency, probably owing to reduced leaf senescence. Although the effect of rootstocks on leaf senescence under K deficiency was significant in some cases, the scion cultivars explained the highest percentage of variations within grafting treatments. The shoot-to-root feedback signal(s), rather than high shoot demand for K nutrition, was involved in the shoot regulation of premature senescence in cotton plants, achieved possibly by altering root K uptake.
authors.affiliation: State Key Laboratory of Plant Physiology and Biochemistry, Key Laboratory of Crop Cultivation and Farming System, Center of Crop Chemical Control, China Agricultural University, Beijing 100193, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Baomin
authors.initials: B
authors.lastname: Wang
authors.forename: A Egrinya
authors.initials: AE
authors.lastname: Eneji
authors.forename: Liusheng
authors.initials: L
authors.lastname: Duan
authors.forename: Zhaohu
authors.initials: Z
authors.lastname: Li
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Tian
mesh_terms: D016922:Cellular Senescence / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D003368:Gossypium / Q000254:growth & development / Q000502:physiology*; D010788:Photosynthesis / Q000502:physiology; D018515:Plant Leaves / Q000254:growth & development / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology*; D018520:Plant Shoots / Q000254:growth & development / Q000502:physiology*; D030821:Plants, Genetically Modified; D011188:Potassium / Q000378:metabolism*; D036226:Seedlings / Q000254:growth & development / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D002734:Chlorophyll; D011188:Potassium