The comparation of drought resistance between Caragana species (Caragana arborescens, C. korshinskii, C. microphylla) and two chickpea (Cicer arietinum L.) cultivars

Water stress is the main environmental factor limiting plantproductivity, especially in arid and semi-arid areas. Within limits, plants adapt to water stress through physiological and morphological adaptations, and leaf water potential (LWP) and leaf relative water content (RWC) are widely used to determine plant water status. Several studies have demonstrated the relationship between RWC and LWP to quantify the dehydration tolerance of tissues: tissues which maintain a high RWC as LWP decreases are more tolerant to dehydration. Caragana arborescens, C. korshinskii. C. microphylla, deciduous shrubs, commonly found in desert and semi-desert zones, northwestern China, and have important ecological and economic values: including playing a key role in vegetation succession from shifting sand dune to sandy grassland, helping to restore degraded land and serving as supplemental forage for livestock. Chickpea (Cicer arietinum L.), annual legume crop, is also considered one of the most drought-tolerant cool season food legumes in these areas. In the present study, predawn LWP and RWC were measured in C. arborescens, C. korshinskii, C. microphylla and two chickpea cultivars, a desi type, cv. Rupali, and a kabuli type, cv. Almaz, when subjected to water deficit in the glasshouse. For each species, 20 plants were randomly designated to one of two treatments: well-watered control (WW) and water-stressed (WS). The WS treatment was imposed by cessation of watering and WW plants were watered every 2 - 3 days to maintain the soil water content (SWC) above 80% field capacity. RWC and LWP were measured at 2 - 3 day interval. The results showed that RWC in chickpea decreased with declining LWP and had significant linear relationship with LWP. However, in C. arborescens, C. korshinskii and C. microphyll, RWC did not decreased (maintaining a steady high water content about 100%) until LWP dropped below -2.4MPa, -2.5MPa and -1.5 MPa, respectively. After that, RWC decreased with declining LWP and had significant linear relationship with LWP. The results showed that RWC was a good parameter to determine the water status in chickpea, but as far as C. arborescens, C. korshinskii and C. microphyll were concerned, it was not. The maintenance of steady high water content in C. arborescens, C. korshinskii and C. microphyll at the beginning of water-deficit period maybe result from rigid and inelastic leaf cell wall in these species, which would provide the basis for sustaining high pre