Quantifying the agronomic performance of new grain sorghum hybrids for enhanced early-stage chilling tolerance

Authors: OSTMEYER, TROY - Kansas State University; BHEEMANAHALLI, RAJU - Kansas State University; SRIKANTHAN, DHANUSH - Kansas State University; Bean, Scott; PEIRIS, K.S.H. - Kansas State University; MADASAMY, PARANI - Srm Institute Of Science And Technology; PERUMAL, RAMASAMY - Kansas State University; JAGADISH, KRISHNA - Kansas State University

Submitted to: Field Crops Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/2/2020
Publication Date: 9/12/2020
Citation: Ostmeyer, T., Bheemanahalli, R., Srikanthan, D., Bean, S.R., Peiris, K., Madasamy, P., Perumal, R., Jagadish, K. 2020. Quantifying the agronomic performance of new grain sorghum hybrids for enhanced early-stage chilling tolerance. Field Crops Research. 258/107955. https://doi.org/10.1016/j.fcr.2020.107955.
DOI: https://doi.org/10.1016/j.fcr.2020.107955

Interpretive Summary: Developing sorghum hybrids that can maintain growth under early-stage chilling temperatures is critical to improve sorghum production and to provide opportunities for expanding sorghum cultivation into more temperate and high elevated regions of the US and the world. Thus the objectives of this research were to (i) Identify sorghum hybrids with enhanced early-stage chilling tolerance with stable agronomic performance; (ii) develop, test and establish an improvised phenotyping approach to better relate controlled environment chamber findings to field conditions and (iii) quantify the degree of early-stage chilling tolerance of newly developed grain sorghum hybrids and the impact on flowering time, yield and quality characteristics. Modifying growth chamber conditions with improved temperature programs more closely matched field conditions and resulted in stronger relationships between field studies and growth chamber studies for screening germplasm for response to chilling stress. This project also found that early planting resulted in longer days to flower and accumulated higher number of growing degree units during grain filling, resulting in extended vegetative period and a similar or higher grain yield, respectively. This research provides improved methods for screening sorghum germplasm for chilling stress and identified changes that occur to sorghum that can be planted earlier in the season. In addition, this research identified a non-tannin sorghum hybrid with enhanced chilling stress.

Technical Abstract: Enhancing chilling tolerance to attain uniform emergence with good seedling vigor with temperatures < 15 oC will enable earlier sorghum planting. Early planted sorghum has the potential to better utilize residual soil moisture and enhance yield through extended vegetative and grain-filling period. The study included 12 entries including 4 new hybrids developed from different hybrid combinations involving 2 seed (A-line) and 3 pollinator (R-line) lines and 3 checks (two inbreds - RTx430 and SQR; and one commercial hybrid). The above entries were phenotyped in field conditions over two years and in controlled environment chambers. An improvised phenotyping approach was devised for controlled environment chambers to better replicate temperature conditions on the field. A systematic testing resulted in early-stage seedling vigor to better represent field grown seedlings, compared to those maintained under constant chilling conditions. Early planting resulted in longer days to flower and accumulated higher number of growing degree units during grain filling, resulting in extended vegetative period and a similar or higher grain yield, respectively. Our most promising tannin free hybrid (ARCH11192A/ARCH12012R) with enhanced chilling tolerance, recorded 23 more days (707 GDU) to reach flowering compared to regular planting with the grain-filling period extended by 3 days (66 GDU). On average, reduction in grain protein and a higher starch concentration was recorded with early planting, indicating longer vegetative stage providing additional carbon for the developing grains at the cost of grain protein. In summary, developing tannin free early-stage chilling tolerant hybrids and optimizing an appropriate planting window would allow for an extended vegetative and grain-filling duration to support higher grain yield and starch concentration.