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|Title:||Growth Curve Analysis of Soybean Cultivars|
|Doctoral Committee Chair(s):||Jackobs, Joseph A.,|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
Biology, Plant Physiology
|Abstract:||To study the methodology for functional growth analysis of soybean and to find out the growth characteristics of soybean cultivars, two experiments were conducted at the Agronomy Plant Pathology South farm of the University of Illinois during the years 1985 and 1986.
In 1985, cultivars Pixie and Williams were planted on May 10 and June 3 and thinned to 120,000, 240,000, and 360,000 plants per hectare. In the following year cultivars Harden, Elgin, Pixie, Williams, and Essex were planted on May 22 and June 10. Biomass was recorded at about weekly intervals in the year 1985. Similarly, biomass accumulation data, leaf number, leaf area, leaf weight, pod weight, etc., were recorded in 1986. Richards function was fit to the biomass data and polynomials to other data.
The Richards function gave excellent fit to the observed data and was better than logistic and Gompertz functions. Use of treatment mean for growth analysis is justified as the parameters of the Richards function fitted to the treatment means were found to be included in the confidence interval of the parameters of the function fitted to the experimental units data. Use of cumulated air growing degree days, calender days, hours of sunshine, and soil growing degree days as independent variables in the Richards function was equally good. Stepwise regression of biomass on weather data selected precipitation, growing degree days, relative humidity and minimum temperature for predictive equations, having 3 to 5 parameters, that accounted for 0.9987 to 0.9997% of the variation in biomass.
Early cultivars had a higher relative growth rate, and crop growth rate, but lower leaf area duration, a later point of inflection, and shorter growth duration than late cultivars. Early cultivars partitioned more assimilates to reproductive parts than late cultivars. Estimates of K, N and leaf area duration increased and seed yield decreased with delay in sowing. Pixie produced the highest yields in 1985 and in early sown plots in 1986, however, Hardin produced the highest yield in late sown plots in 1986.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.
|Date Available in IDEALS:||2014-12-16|