HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by De Bruin, J. L. Articles by Pedersen, P. PubMed Articles by De Bruin, J. L. Articles by Pedersen, P. Agricola Articles by De Bruin, J. L. Articles by Pedersen, P. Related Collections Soybean Crop Growth and Development

CROP ECOLOGY, MANAGEMENT & QUALITY

New and Old Soybean Cultivar Responses to Plant Density and Intercepted Light

Dep. of Agronomy, Iowa State Univ., 2104 Agronomy Hall, Ames, IA 50011-1010

^* Corresponding author (jsndbrn{at}iastate.edu).

Genetic gain for new soybean [Glycine max (L.) Merr.] cultivars is substantial, and research suggests this is partially explained by greater tolerance to increased plant densities. We conducted an experiment to determine if greater tolerance to increased plant density and more efficient use of cumulative intercepted photosynthetically active radiation (CIPAR) partially explained the yield difference of two old soybean cultivars and two new cultivars. Soybean cultivars were grown in 38-cm spaced rows at final plant densities of 4.9, 14.8, 24.7, 34.6, and 44.5 plants m^–2 for 2 yr in Ames, IA. New cultivars averaged 914 kg ha^–1 and 4.9 g plant^–1 greater yield compared with old cultivars averaged across years and plant densities. Yield plateaus occurred at plant densities of 23.0 plants m^–2 for new cultivars and 19.9 plants m^–2 for old cultivars. Each cultivar group showed a similar yield decline per plant to increased plant density. New and old cultivars showed a similar response to increasing values of CIPAR, attaining a 95% relative yield plateau at 466 MJ m^–2. Soybean yield response to increased plant density and CIPAR has not changed over time, and genetic gain from new cultivars is associated with more efficient use of light.

Abbreviations: CIPAR, cumulative intercepted photosynthetically active radiation • CTU, cumulative thermal units • DAE, days after emergence • FLI, fractional light interception • LI, light interception • PAR, photosynthetically active radiation • RUE, radiation use efficiency