18th Congress of the European Society for Agronomy

Genotype-Environment Interactions in pre-harvest sprouting of wheat

Not scheduled

15m

Les Dortoirs (1st floor) (The Couvent des Jacobins)

Poster Synergies of technologies Poster session #2

Speaker

Mrs Sandra Hull (Stellenbosch University)

Description

1. Introduction
   Pre-harvest sprouting (PHS) is the untimely germination of the seed while intact to the plant at or before harvesting occurring in a multitude of crops including wheat (Triticum aestivum L.). The incidence of PHS is influenced by the conditions of rainfall, temperature, and humidity as well as a lack of genetic dormancy, a quantitative genetic trait, during these conditions. This results in the synthesis of the hydrolytic enzyme alpha-amylase which, in turn, decreases falling number, thereby reducing grain yields and quality with an associated decrease in grain price. Given the ongoing changes in climate patterns and the complexity of PHS, gaining an understanding of the genotype x environment interaction, resulting in PHS, has become imperative. The aim of this study is to evaluate the influence of the environment, genotype and their interaction on PHS of wheat cultivars.
2. Materials and Methods
   Trials were conducted in 2021, 2022 and 2023 at two sites in the Eastern Cape province, South Africa, and in 2022 and 2023, nine additional locations in the Western Cape province were included. A total of 40 commercial wheat cultivars were planted in 2021 while 15 commercial wheat cultivars were planted in 2022 in the Eastern Cape, with three replications. In 2022 and 2023 in the Western Cape, 17 commercial South African cultivars were planted with four replications. At anthesis 10 spikes per plot were labelled and later hand-harvested during harvest. Harvested spikes were subjected to simulated conducive conditions for 72 hours in a rainfall simulator and assessed for PHS using a scoring matrix of one to eight where one had no sprouting and eight was fully sprouted. Falling number and alpha-amylase activity were analysed on harvested grain. Statistical analyses, including mixed models, Additive Main Effects and Multiplicative Interaction (AMMI) analyses and correlations were, performed using R.
3. Results
   Genotype x environment interactions (P<0.05) were present in the Eastern Cape in 2021 and 2023 for all assessments, however, no interaction (P>0.05) was present in 2022. In the Western Cape in 2022 and 2023, G x E interactions (P<0.05) were present for visual score and alpha-amylase activity, however, no interaction was present for falling number (P>0.05). Correlations between weather conditions during the season and PHS assessments indicated that weather conditions, including minimum and maximum temperature, minimum and maximum relative humidity, and rainfall during August, September and October are influential in PHS susceptibility and not only the conditions during harvesting.
4. Discussion
   Since the cultivar and environment play a key role in the incidence of PHS, identifying a cultivar that is most suited to a particular environment is imperative. In the Western Cape, a significant proportion of variation was explained by the AMMI analysis identifying that specific cultivars were better suited to particular environments in terms of visual assessment, falling number and alpha-amylase, while some cultivars were moderately stable and adapted to all environments. A similar result was present in the Eastern Cape, where environmental factors influenced the expression of PHS in terms of visual score, falling number and alpha-amylase assay. Additionally, the correlogram correlations indicated that PHS is influenced by weather conditions during critical growth stages in months before harvesting, not only during the harvesting period. The level of seed dormancy experienced during harvest is linked to environmental conditions throughout the season. Therefore, the risk of PHS can be associated with conditions during critical growth phases. Additional research is essential to determine the precise weather conditions affecting PHS susceptibility during specific critical growth phases. By identifying the weather conditions that are most influential in maintaining seed dormancy during different critical growth stages, while linking this to a specific cultivar, the risk of PHS may be reduced.