Genetic diversity of sugar beet under heat stress and deficit irrigation

Authors: ABUO-ELWAFA, SALAH - Assiut University; AMIN, ABU EL0EYUOON - Assiut University; Eujayl, Imad

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2020
Publication Date: 8/17/2020
Citation: Abuo-Elwafa, S.F., Amin, A.A., Eujayl, I.A. 2020. Genetic diversity of sugar beet under heat stress and deficit irrigation. Agronomy Journal. 112(5):3579-3590. https://doi.org/10.1002/agj2.20356.
DOI: https://doi.org/10.1002/agj2.20356

Interpretive Summary: Heat stress and shortage of irrigation water are becoming critical for sugar beet production in Egypt, as sugar beet cultivation has expanded to more than 500,000 acres. Availability of varieties with improved tolerance to heat stress and limited irrigation is important for sugar beet production in this region. This research evaluated 18 sugar beet germplasm from USDA ARS under winter climatic condition in Upper Egypt (Assiut Province) for two seasons (2016/17 and 2017/18). Six promising lines were identified for high yield and optimum quality under these climatic conditions and controlled deficit irrigation. There was significant variation among breeding lines in response to the heat stress and deficit irrigation. These results indicate a high degree of genetic variability in the evaluated lines. In general, the variations in root yield showed negative effect due to deficit irrigation. There was a linear relationship between overall stress index and average root and sugar yields. Selection for high yielding breeding lines under both optimum- and deficit-irrigation conditions can be achieved under these conditions. We identified the best performing breeding lines (USKPS25 and USC944-6-68) that are most likely adapted to deficit irrigation and high temperature. These lines are suitable to be utilized in the proposed sugar beet breeding programs in Egypt. Additionally, as these lines are originated in the USA, they are newly identified genetic resources to be utilized for drought stress breeding programs.

Technical Abstract: In the light of climate changes and globalwarming, as well as the rapid expansion in sugar beet (Beta vulgaris L.) cultivation in Egypt, the development of sugar beet varieties with improved tolerance to high temperature and deficit irrigation is of great importance. The objective of this studywas to evaluate sugar beet genotypes under high temperatures and deficit irrigation conditions for further identification and selection of heat and drought tolerant genotypes. In the current study, a panel of 18 sugar beet breeding lines produced at the USDA–ARS–NWISRL, Kimberly, ID, and the commercial sugar beet cultivar Kawimera were evaluated for yield and quality under high temperature. Six promising lines in terms of yield and quality were further evaluated under both high temperature and deficit irrigation for two growing seasons. All lines performed differently under deficit irrigation, indicating a high degree of genetic variability in the evaluated lines. Additionally, yield traits showed negative effect due to deficit irrigation. A significant positive correlation was observed between stress tolerance index (STI), and average root and sugar yields under stressed and non-stressed conditions. A linear relationship between STI and average root and sugar yields indicates that STI is a reliable stress index to select high yielding genotypes under both optimum- and deficit-irrigation conditions. USKPS25 and USC944-6-68 breeding lines are most likely adapted to deficit irrigation and high temperature and suitable to be utilized in the proposed sugar beet breeding programs in Egypt.