The influence of temperature on germination and seedling growth of sorghum

The extensification of agricultural activities to suboptimal areas, including dryland, is being considered. Sorghum as a drought-tolerant crop is usually cultivated in dryland areas in Indonesia. However local farmers are having difficulty in choosing quality seeds suitable for the specific area temperature condition. This study evaluated the physical quality of commonly used sorghum cultivars in Indonesia and their responses to several germination temperatures. The three sorghum cultivars used were Strong Brown (SB) Sorghum known as the local cultivar, Pale yellow (PY), and Light Brown (LB). The result revealed that each sorghum cultivar has specific seed characteristics, especially in the color, shape, and size of the seeds. The seeds of the Light Brown sorghum had the highest quality, followed by Strong Brown sorghum and PaleYellow sorghum cultivars based on both the tetrazolium test and the direct germination test. The optimum temperature for sorghum seed germination ranged from 25 to 35oC. Each sorghum cultivar has its specific temperature requirement for germination. Low temperature (20°C) potentially reduces the percentage of germination and delays the seed germination time of these three cultivars. LB cultivar has the highest relative growth rate (RGR) from the first week to the second week (R1), while the RGR from the first week to the third week (R2), LB sorghum cultivar is in the second position after the PY cultivar. Cultivar LB is suggested for cultivating in elevations 300-500 m asl, moreover cultivar SB elevations 50-250 m asl.