Document Type : Original Article
Authors
1
Agronomy Department, Faculty of Agriculture, Cairo University, Giza 12613, Egypt
2
Agronomy Department, Faculty of Agriculture., Cairo University 12613, Giza, Egypt
Abstract
DROUGHT stress affects greatly on sugar beet productivity; thus, two field trials were conducted to investigate the effects of foliar applications of L-ornithine (150 ppm), ascorbic acid (500 ppm), and silicon (2000 ppm) on the performance of three sugar beet cultivars (Neagre, Dreeman, and BTS 645) under four irrigation levels (50%, 40%, 30%, and 20% of field capacity (FC)). Results showed that anti-stress compounds, irrigation levels, and cultivars significantly affected growth traits (dry weight of leaves and roots, leaf area index) and yields of top, root, and white sugar. Sucrose and extractable sucrose percentages were enhanced under moderate drought levels. However, increasing drought to 20% of field capacity had the most adverse effects, reducing extractable sucrose by 1.3-2.7%, root yield by 29-33%, and white sugar yield by 38-40% compared to 50% field capacity irrigation in both seasons. Cultivar performance varied under different drought and anti-stress compound combinations. Watering at 40 or 50% field capacity and spraying with L-ornithine increased root weight and yields. Watering at 30 or 40% field capacity and spraying with ascorbic acid or silicon increased sucrose and extractable sucrose contents. Among the compounds, L-ornithine had the greatest impact on growth and yield traits, while ascorbic acid and silicon influenced the chemical constituents of beet juice. The Dreeman cultivar exhibited the highest drought tolerance based on tolerance index (TOL), stress susceptibility index (SSI), geometric mean production (GMP), and stress tolerance index (STI) for root and sugar yields. GMP and SSI indices are effective for selecting high-yielding, stress-tolerant genotypes.
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