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Gas Exchange of Field‐Grown Soybean under Drought 1
Author(s) -
Cortes P. M.,
Sinclair T. R.
Publication year - 1986
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1986.00021962007800030012x
Subject(s) - cultivar , biology , drought stress , growing season , agronomy , horticulture
Drought stress has been shown to reduce leaf carbon exchange rates (CER) and to hasten leaf senescence of plants. This study was undertaken to assess concurrently the relative effects of each process on seasonal accumulation of C for soybean [ Glycine max (L.) Merr.| grown under field conditions. Leaflet CER and water vapor exchange rates were measured continuously during drought stress treatments of two indeterminate cultivars. The cultivars differed in maturity with ‘Wilkin’ being in maturity group 0 and ‘SRF 150’ being maturity group I. Gas exchange measurements were made using an open system with assimilation chambers enclosing uppermost fully expanded leaflets. Data were recorded concurrently every 12 min for leaflets attached to plants in an irrigated treatment and in treatments drought stressed at differing stages of reproductive growth. As a result of drought during reproductive growth, CER of both cultivars was reduced by approximately 25% for the remainder of the season. Drought during flowering to mid‐podfill did not seem to hasten leaf senescence in either cultivar. However, drought after mid‐podfill resulted in a 5 to 10 day earlier leaf senescence of these leaves at the top nodes of the plants. These data suggest that reduced CER for the remainder of the season was a consistent consequence of drought stress during reproductive growth. Hastened leaf senescence could further reduce total accumulated C if drought occurred late in reproductive growth.