Seed-to-seed early-season cold resiliency in sorghum

Abstract

Early planted sorghum usually experiences cooler day/night temperatures, which may result in delayed growth, floral initiation, and infertile pollen, limiting productivity in high altitudes and temperate regions. Genetic variability for cold tolerance in sorghum has been evaluated by characterizing germination, emergence, vigor, and seedling growth under sub-optimal temperatures. However, the compounded effect of early season cold on plant growth and development and subsequent variability in potential grain yield losses has not been evaluated. Agro-morphological and physiological responses of sorghum grown under early-, mid-, and standard planting dates in West Texas were characterized from seed-to-seed. A set of diverse lines and hybrids with two major sources of tolerance, and previously selected for seedling cold tolerance were used. These were evaluated with a standard commercial hybrid known for its seedling cold tolerance and some cold susceptible breeding lines as checks. Variabilities in assessed parameters at seedling, early vegetative, and maturity stages were observed across planting dates for genotypes and sources of cold tolerance. Panicle initiation was delayed, and panicle size reduced, resulting in decreased grain yields under early and mid-planting dates. Coupled with final germination percent, panicle width and area were significant unique predictors of yield under early and mid-planting dates. Significant variability in performance was observed not only between cold tolerant and susceptible checks, but noticeably between sources of cold tolerance, with the Ethiopian highland sources having lesser yield penalties than their Chinese counterparts. Thus, screening for cold tolerance should not be limited to early seedling characterization but should also consider agronomic traits that may affect yield penalties depending on the sources of tolerance.

Improving abiotic stress tolerance in sorghum: focus on the nutrient transporters and marker-assisted breeding

“…Salinity reduces germination percentage, germination index, shoot length, root length, seedling vigor index and fresh and dry weight of shoot and root (Dehnavi et al 2020). Cold stress adversely affects the early growth and development of sorghum including emergence, seedling vigour, time to flowering, pollination, number of seeds in panicles and pollen production and general metabolism (Emendack et al 2021;Schaffasz et al 2019). All the above studies have revealed that the growth and yield of sorghum are severely affected by various abiotic stresses.…”

Implementation of Epigenetic Variation in Sorghum Selection and Implications for Crop Resilience Breeding

“…Tests showed a significantly greater variation and potential for cold tolerance in the msh1-derived epi-lines than those of their isogenic wildtype counterparts for seed germination and early plant growth features with no change in anthesis time. Successful early planting of sorghum, requiring cold tolerant seed germination, provides opportunity for crop expansion to new growing areas and efficient resource utilization (Emendack et al, 2021).…”

Responses of sorghum to cold stress: A review focused on molecular breeding

“…The term "cold tolerance or chilling tolerance" is used to describe the ability of sorghum to germinate, grow, and produce seed under conditions of low temperature but above freezing temperatures (Singh, 1985;Osuna-Ortega et al, 2003;Vera-Herna ́ndez et al, 2018;Emendack et al, 2021). Low temperature is one of the main abiotic stressors that affect plant growth and development and is a principal determinant of the geographical distribution of plants (Hurry et al, 2002;Mehrotra et al, 2020).…”