Examination of root characters, isotope discrimination, physiological and morphological traits and their relationship used to identify the drought tolerant sunflower (Helianthus annuus L.) genotypes

Abstract

SUMMARY In order to study the drought tolerance in sunflower an experiment was conducted with 65 sunflower entries including cms -lines, R-lines, inbred, hybrids and varieties grown in temporary cement root structures. During the active vegetative growth, several physiological parameters were recorded. As flowering plants were harvested, the observations on root traits were recorded. Results showed a wide and significant genetic variability for leaf area, specific leaf area, plant height, chlorophyll content, root length, root dry weight, root volume and total dry matter (TDM). Δ13C, a surrogate approach to quantify water use efficiency also showed a significant variability. Since our major objective was to look for genetic variability for drought tolerant traits and to select lines with superior drought tolerant lines, the entries were grouped into high and low root, TDM and Δ 13 C types. Promising sunflower entries were selected based on high TDM with better root system and low Δ 13 C to be used for heterosis breeding to develop drought tolerant hybrids. In all screened entries, it was examined how the TDM and its components are related to each other by correlating many growth parameters with TDM. The results revealed that a positive and significant relationship between total leaf area and TDM was found. Similarly root dry weight also showed a significant positive relationship with TDM. However, Δ 13 C values neither related to TDM nor to root dry weight.