Evaluation of Kabuli Chickpea genotypes for tropical adaptations including drought tolerance, disease resistance and functional food properties

Chickpea, a high value winter legume, is grown predominantly as a rainfed crop in Australia. The chickpea industry is expanding in northern Australia rapidly. The region’s summer dominant rainfall and changing climate patterns cause drought stress and diseases, limiting yield and quality in tropical production environments. Breeding tropically adapted, drought and disease tolerant high yielding Kabuli chickpea will support sustainable chickpea production in Northern Australian region. Eight chickpea genotypes were evaluated for tropical adaption and yield performance, in central Queensland, Australia, using garden raised beds in open field. There was significant variation in phenological, morphological, physiological and reproductive traits for these tested genotypes. Hand harvested seed yields of 746 g/m2 and 626 g/m2, equivalent to 7.46 and 6.26 t/ha was recorded for AVTCPK#6 and AVTCPK#19, respectively. Higher leaf photosynthetic rate, lower stomatal conductance, and lower transpiration rates contributed to higher water use efficiency (iWUE) in AVTCPK#6 and AVTCPK#19. Furthermore, higher %Ndfa in AVTCPK#6 (71%) followed by AVTCPK#19 (63%) indicated for greater symbiotic nitrogen fixation by these genotypes. Chickpea genotypes were also evaluated under glasshouse conditions using lysimeter with full irrigation (well-watered WW) and water withheld at flowering (water-stressed WS) treatments for assessing drought tolerance. Significant reduction in chlorophyll content, stomatal conductance, carbon assimilation rate, and internal carbon concentration were observed under water stress compared to well-watered plants indicating significant reduction of yield in water stress treatment. Genotype AVTCPK#6 and AVTCPK#19 were late maturing genotypes recorded high yield both on well-watered and water stress condition with higher WUE whereas, genotype AVTCPK#1 and AVTCPK#12 (early maturing) showed drought susceptibility with lower seed yield. The other genotypes (AVTCPK#3, AVTCPK#8, AVTCPK#24 and AVTCPK#25) with medium maturity showed medium seed yield with intermediate tolerant to drought stress. The Kabuli chickpea genotypes grown in the raised bed were also assessed for bioactive compounds namely for total phenolic content (TPC), total antioxidant capacity (using both FRAP and CUPRAC assays), and profiling of individual phenolic acids using high-performance liquid chromatography (HPLC). Significant variation in TPC (40.9 - 69.1 mg GAE/100g), FRAP (23.7-31.1 mg TE/100g), and CUPRAC (378-389 mg TE/100g) was recorded among the eight Kabuli genotypes. The presence of two phenolic acids (gallic acid and p-hydroxybenzoic acid) and two flavonoids (catechin and quercetin) in all tested genotypes, with significantly different concentrations between them, suggests substantial genetic variation. This diversity is crucial for targeted breeding programs aimed at developing high bioactive Kabuli chickpea. These genotypes not only offer good quality protein and carbohydrates but also contain phytochemicals with potential health benefits, allowing growers and producers to target premium markets for Kabuli chickpea. Finally, these Kabuli chickpea genotypes were also evaluated for Ascochyta blight (AB) tolerance at the seedling stage using spray inoculation and genotyped using the Marker Aided Selection (MAS) method with markers tightly linked to Quantitative Trait Loci (QTL). Genotypes AVTCPK#6 and AVTCPK#14 showed a moderately resistant response, with only AVTCPK#6 expressing markers associated with AB resistant bands. These moderately resistant genotypes can be exploited further in chickpea breeding program for the development of AB tolerant chickpea in commercial cultivars.