Abstrakt

Evaluation of sweet sorghum accessions for seedling cold tolerance using both lab and field cold germination test

Ming Li Wang*, Zhanguo Xin, Gloria Burow, Junping Chen, Phiffie Vankus, David Pinnow, Brandon Tonnis, Hugo Cuevas, Jianming Yu.

Objective: Seedling cold tolerance is one of the important traits for sweet sorghum production. This study is to evaluate the method for identification of sweet sorghum accessions with seedling cold tolerance using both lab cold germination and field early-spring cold planting.

Methodology: Sorghum seeds were germinated in growth chamber (under lab cold condition) at a constant 12°C for five weeks. After two weeks, germinated seeds and germination rates were counted and calculated at weekly intervals for four times. The same seed lots for lab cold test were also planted 45 days earlier than the normal planting time in the field (early-spring cold planting). In addition to seedling dry weight, germinated seeds and seed germination rates were also counted and calculated at weekly intervals for three times.

Results: In this study, a high correlation coefficient between lab germination rate and field germination rate (R2=0.503, p<0.0001) was observed. In general, lab germination rate can predict the field germination performance; but some discrepancies between field and lab tests were also observed for some accessions. Among 212 sweet sorghum accessions tested, several sweet sorghum accessions with seedling cold tolerance were identified from both lab and field tests. These accessions will be useful materials for development of sweet sorghum cultivars with early spring cold tolerance.

Conclusion: Compared with the field test, the lab test is less labor intensive. For a large-scale screening of seedling cold tolerance, the lab test may be conducted initially followed by selection of superior accessions from the lab test for further evaluation under field conditions.