Document Type : Original Article

Authors

• Hassan Hamidi ¹
• S.Sanaz Ramezanpour ²
• Masoud Ahmadi ³
• Hassan Soltanloo ²

¹ Ph.D. student, Plant Breeding, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran

² Associate Professor, Department of Plant Breeding and Biotechnology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran

³ Assistant Professor, Sugar Beet Research Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran.

Abstract

Introduction
The dry and semi-arid climate of the country has become inevitable the cultivation and production of crops under the conditions of environmental stresses (drought, salinity and heat).Crops are show different reactions against these stresses. The occurrence of any of the stresses, or a combination of them, leads to a reduction in production. Sugar beet is one of the plants that tolerates these stresses. The aim of this research was to determine the tolerance of sugar beet S1 pollinator lines to drought stress in field conditions in terms of yield and physiological traits so that based on the results, a model could be presented for better and more effective management of water on farms.

Materials and methods
This experiment was conducted to evaluate the physiological characteristics of 34 sugar beet genotypes (30 S1 pollinator lines with three controls including Shokoofa, Motahar and Paya and Origin population) under normal irrigation and drought stress conditions in a Randomized Complete Block Design with three replications at experimental field of Khorasan Razavi Agricultural and Natural Resources Research and Education Center in 2016. Irrigation was done routinely up to the thinning and weeding stage. Subsequent irrigations were done after 90 mm and 200 mm evaporation from the class A evaporation pan in non-stress and stress conditions, respectively. In this research, traits such as root yield, sugar content, sugar yield, chlorophyll, Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), Index of difference between the temperature of environment and leaf, leaf relative water content, specific leaf weight, succulence index, specific leaf area and electrolyte leakage were measured. Analysis of variance and estimation of correlations were performed with SAS 9.1 software and also factor analysis was done using Statgraphics 18 software.

Results and discussion
Results showed that in both conditions (non-stress and drought stress conditions) there are significant different (p≤0.01) between all genotypes for all traits. Combined analysis of variance showed that there was a significant difference (p≤0.01) among studied genotypes and different irrigation regimes in the most traits. In normal irrigation and drought stress conditions, Motahar and S1-15 line had the highest sugar yield (9.09 and 10.5 ton/ha), respectively. Correlation coefficients showed that root yield had a positive and significant correlation with sugar yield and NDVI in normal and stress conditions. In both conditions (non-stress and drought stress conditions), factor analysis led to introduce four main factors which explained 69.55 and 74.75 percent of total variation, respectively.
Conclusions
In general, the results showed that there are considerable variations in yield and physiological traits among the different genotypes of sugar beet due to the potential for drought tolerance in them.

Keywords

• Genotype
• Root yield
• Sugar yield
• Water deficit stress