Response of Height Genotypes of sorghum (Sorghum Bicolor (L) Moench) to Different Day Lengths

Abstract

The response of height genotype of wrghum to different day lengths wes studied in the University of Wisconsin Biotron.Two day length chambers were used to represent a tropical climate and a temperate climate, which had l2hour day length and l5hour day length, respectively. Eight genotypes of sorghum were used in this study. The heights of sorghum genotypes were significantly affected by photoperiod at 30 dayr after planting. There also were diffe!nces in plant height at the flowering dew due to the effect of genotypes and day length. The highly significant differe6ce in day length raponse of plant height showed that with increased day length there was a corresponding increase in plant height. At the longer day (15 hours), more vegetative growth ocarredThe heights of 1 - dwarf, 2 - dwarf, and 3 - dwarf hybrid milos were taller than the average of their parents in both day length chambers. There were differences in days to flower ascribed to genotypes and day lengths. There was a corresponding increase in days to flower and in plant height with increased day length. At both day lengths all milo hybrids (l-dwf, 24wf. 3-dwf) flowered earlier than their respective parents. In addition to the biotron study, the field trial wesconducted at the Arlington Experimental Farm using 24 sorghum genotypes. The field trial revealed that by using one parent of the 4-dwf class, the plant height can be reduced. The yield of 24 sorghum genotypes varied widely from 2 144 kg to 5 672 kg per hectare for C-43 y+ and NK 233, respectifely. All genotypes, except SM 100, grown in the controlled environment chamber flowered in less time than those grown in the field. One - dwarf and 3 - dwarf milo hybrids took significantly longer to flower than their respective parents, which was in contrast with that observed in the Biotron.