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Abstract Detail


Silim, Salim N. [1], Morrison, Malcolm J. [1], Cober, Elroy R. [1].

Changes in photosynthetic components in short-season Canadian soybean cultivars from seven decades of genetic improvement.

Soybean (Glycine max (L.) Merr.) yield in Canada has increased since the crop was first cultivated in the early 1930s. Much of this increase is attributed to the genetic improvement of cultivars. The physiological mechanisms underlying these yield gains are being examined. While photosynthesis is the ultimate basis of yield, improving photosynthetic efficiency has played only a minor role in improving crop yields to date. The objective of this work was to characterise and assess the extent of changes in important leaf photosynthetic traits in historical Canadian soybean cultivars released over time. Sixteen cultivars representing seven decades of breeding and selection (1934–2000) were planted in a randomized complete block design with four replications, across 3 years in Ottawa, ON. Additional plants were grown in growth chambers for detailed physiological studies. Leaf level photosynthetic rate (A) and stomata conductance (gs) were measured several times each year. Leaf N content, leaf 13C composition (d13C) and leaf mass area (LMA) were determined on samples from the growth chamber plants. A and gs increased with year of release (YOR). Intrinsic water use efficiency (A/gs, WUE), d13C, LMA and leaf N content decreased with YOR. There was a strong positive correlation between A and N, and a negative correlation between LMA and A, LMA and WUE, and LMA and d13C. There were no changes in mesophyll conductance (gm) with YOR. The increase in A with year of release appears to be mostly the result of increased gs in the cultivars.

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1 - Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, 960 Carling Avenue, Ottawa, ON, K1A 0C6, Canada

stomatal conductance.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PAG007
Abstract ID:1217
Candidate for Awards:None

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