Sorghum Tips

Hybrid Selection – Plant Height and Grain Yield

This tip was provided by:

Ronnie Schnell, Cropping Systems – Statewide, College Station, ronschnell@tamu.edu

Statewide

Hybrid Selection – Plant Height and Grain Yield

In a previous tip, we discussed variation of flowering times by maturity group and production region and the impact maturity has on grain yield. When soil moisture is not limiting, later maturing hybrids generally produce greater yields. Will plant height affect grain yield? Plant height is generally a function of maturity and internode length. Various maturity genes control flowering and internode length is controlled by four dwarfing genes. In addition to increasing plant height, later maturity generally results in greater leaf number.

Grain sorghum performance trials conducted by the Soil and Crop Science Department across Texas routinely measure plant characteristics, including days to bloom, plant height, panicle exertion, etc. Plant height, measured from the ground to the tip of the panicle, is recorded for every plot each year in the statewide sorghum performance trials (about 1,600 plots per year). Average plant height for maturity groups and production regions are shown in figure 1.

Figure 1. Plant height (inches) by maturity group and production region.

For every production region in Texas, plant height is positively correlated with grain yield (Figure 2). Looking within maturity groups, taller plants generally yield better than shorter plants. Although, variation in plant height within maturity groups may reflect variation in maturity more so than variation in internode length.  Given that taller plants yield better, are they more susceptible to lodging? For short stature grain sorghums evaluated in the statewide testing program, no correlation between plant height and lodging was observed during the last four years.  Other factors such as stalk thickness (also affected by plant populations), stress tolerance and disease resistance may have greater influence on susceptibility to lodging. For more information on sorghum performance trials, visit: http://varietytesting.tamu.edu/grainsorghum/.

Figure 2. Impact of plant height (inches) on grain yield (lbs/acre) for production regions in Texas. Plant height is the average height for maturity groups (Early, Medium-Early, Medium, Medium-Late, Late) by region.