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ARS Home » Southeast Area » Raleigh, North Carolina » Soybean and Nitrogen Fixation Research » Research » Publications at this Location » Publication #159621
Title: BREEDING FOR YIELD IMPROVEMENT OF TROPICAL SOYBEANS

Author
item MACHIKOWA, THITIPORN - SURANAREE UNIV, THAILAND
item LAOSUWAN, PAISAN - SURANAREE UNIV, THAILAND
item Burton, Joseph

Submitted to: Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/20/2003
Publication Date: 11/5/2003
Citation: Machikowa, T., Laosuwan, P., Burton, J.W. 2003. Breeding for yield improvement of tropical soybeans [abstract]. Agronomy Society of America, Crop Science Society of America, Soil Science Society of America Meeting, Denver, CO, Nov. 2-6.

Interpretive Summary:

Technical Abstract: Early maturing varieties of soybean [Glycine max (L.) Merr.] produce a lower yield than medium and late maturing varieties due to small plant stature and less profuse branching. The objective of this study was to determine the yield response of early, medium and late maturing varieties to different between row and within row spacings. The experiment was carried out in the dry and wet seasons. The study was grown in a split-split plot design with three replications. Three varieties of soybean, CM2, KUSL20004 and KKU35, representing early, medium and late varieties, respectively, were used as the main plots. Three row widths including 50, 40 and 30 cm were the sub plots and three plant spacings within row of 10, 5 and 2.5 cm were the sub-sub plots. Varieties, row widths and plant spacings affected yields and most other characters. Seed yield of CM2 (an early variety), averaged over all spacings, outyielded KUSL20004 and KKU35. There was a positive and linear yield response to increased plant densities. The rate of increase due to decreasing row width was greater than that the rate of increase due to decreasing plant spacing. On the other hand, at high populations, the response to increased population densities of medium and late varieties was small. The increase in plant densities reduced all yield components of soybean accept seed size. However, the reduction rate of CM2, the early variety, was lower than other varieties. In conclusion, this study showed that seed yield of early variety of soybean could be increased by increasing population densities over those recommended. The spacing of 40 cm between row and 5 cm between plants should be advisable.