Morphological Changes with Advancement of Sorghum Hybrids.

For the past six decades, efforts in plant breeding have resulted in a number of improved sorghum hybrids. Sorghum grain yield has improved substantially since the mid-1950s, when hybrid sorghum production began. The objective of our study was to determine what aspect of grain sorghum morphology and water use might have changed with hybrid improvment and to this yield increase. Data from selected irrigated and dryland grain sorghum performance tests in different Kansas counties were analyzed. A 2-yr (2007 and 2008 summer) greenhouse experiment was also conducted with five hybrids: P848/RS610, P828/P833, P8585, P8385, and P85G46, which were released in 1954-1964, 1964-1974, 1974-1984, 1984-1994, and 1994-2005, respectively. Hybrid performance test results showed that there was an increase in dryland sorghum hybrid performance but irrigated grain sorghum yields were almost constant for the past six decades. The greenhouse study showed an increase in root dry weight with hybrid advancement. The recent hybrid in the experiment had higher root biomass than the oldest. Leaf biomass also increased considerably with hybrid advancement over time. The recent hybrids also have longer panicle and shorter peduncle length. Hybrid development programs created hybrids with improved morphological characteristics that might have enabled greater use of available resource.