Trends of seasonal forage yield changes of triticale in the southern Great Plains of the United States

Background:The focus of triticale breeding in the southern Great Plains of the United States has been to increase forage yield for autumn-winter seasons when most other forage species are dormant.This study aims to estimate the trends of seasonal yield changes over time.Methods:Yield trials had been conducted in a randomized complete block design for up to two decades.Seasonal yield changes over time were estimated using linear regression analysis.Results:The analysis revealed a significant positive relation between autumn forage yield(relative to common checks)and calendar years when the trials were conducted.The estimated improvement of autumn forage yield was about 1.9%per year on medium and heavy soil at Ardmore,Oklahoma,and about 5.4%per year on light soil at Burneyville,Oklahoma.However,winter forage yield change was minimal and the spring forage yield increase was negative,although this decline was not significant.Total forage yield improvements were about 0.6%and 0.7%per year at Ardmore and Burneyville,respectively.Similar results were also observed when years of cultivars'introduction were used instead.Conclusions:The results indicate a significant gain in autumn forage yield,but a minor gain in the total forage yield due to the yield tradeoff between the autumn and spring seasons.