Biplot analysis for yield and quality traits and comprehensive evaluation of sugar beet varieties treated by abscisic acid under water deficit stress

Two field experiments were carried out during two growing seasons at the private farm located in the Kafr El Sheikh governorate, North Nile Delta, Egypt (31° 07' N latitude and 30° 05 E longitude). The purpose of the study was to examine the effects on the yield and quality of the five sugar beet varieties, namely BTS 970, Husam, Karam, Sandor, and Shantala-KWS, of two irrigation intervals, namely control (2-week interval) and water stress (4-week interval), as well as three rates of ABA (control = water, 1000, and 3000 ppm). The results showed that the five sugar beet varieties differed significantly in how they responded to the three ABA concentrations under water deficit stress in terms of root length, root diameter, number of leaves, root yield, sucrose%, total soluble solids percentage (TSS%), sugar lost to molasses percentage (SLM%), extractable sugar percentage (EXT%), and sugar yield. In both seasons, the Husam and Karam varieties recorded the lowest mean values of these traits, while the Shantala-KWS variety had the highest mean values. The sugar beet roots with ABA concentrations up to 3000 ppm also showed an increase in root yield, number of leaves, root diameter, root length, sucrose%, and TSS%. These traits also showed the highest mean values. The control treatments (water spray) showed the lowest mean values. On the other hand, the two seasons differed significantly in water deficit stress (4 weeks). The study recommends using the GT biplot analysis method to evaluate the adaptability of varieties across various environments