Submitted to: Plant and Soil
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2004
Publication Date: 5/1/2004
Citation: Hacisalihoglu, G., Ozturk, L., Cakmak, I., Welch, R.M., Kochian, L.V. 2004. Genotypic variation in common bean in response to zinc deficiency in calcareous soil. Plant And Soil Journal. 259:71-83. Interpretive Summary: Crop yields are often limited by low soil levels of mineral micronutrients such as zinc (Zn). It has been estimated that 30% of the world's arable soils are Zn deficient. There is significant genetic variation both within and between plant species in their ability to maintain significant growth and yield under Zn deficiency conditions; this has been termed Zn efficiency (ZE). In recent years, there has been considerable interest in elucidating the physiological mechanisms that confer ZE, as an understanding of these mechanisms is necessary to help develop more Zn efficient crops. In this investigation, we looked at genetic variation in ZE by growing 35 bean cultivars on either Zn deficient or sufficient soils. A significant variation in ZE was determined, and as much as a 10-fold difference in ZE efficiency was measured between the most efficient and inefficient cultivars. No differences in shoot or seed Zn concentration were observed between the different cultivars, but shoot Zn content was higher in efficient genotypes, because much more shoot biomass was produced under Zn deficient conditions. It was concluded that Zn efficient genotypes either can partition more of the shoot Zn into the young growing shoot tissue, and/or the efficient cultivars can more efficiently utilize the low levels of cellular Zn that occur when plants are grown on low Zn soils.
Technical Abstract: Greenhouse experiments have been carried out to study the genotypic variation among 35 bean (Phaseolus vulgaris L.) genotypes with regards to tolerance to zinc (Zn) deficiency (Zn efficiency). Plants were grown for 45 days in Zn deficient soil supplemented with 0 or 5 mg Zn g-1 soil) and analyzed for Zn efficiency, plant Zn concentration and content, and the distribution of Zn between old and young parts of the shoot. Zn efficiency (ZE) was defined as the ratio of dry matter production at low and high Zn supply and was calculated for the whole shoot as well as for young and old parts of the shoot. There were marked differences in ZE among the bean genotypes. Genotypes G4449 and G11360 were about 2-fold and 10-fold more Zn-efficient than G11229 and G3871 in whole shoot and young-part based ZE, respectively. Interestingly, the older portions of the shoot for most genotypes had higher dry matter production under Zn deficiency than under sufficient Zn supply, suggesting that there was a significant inhibition of new shoot growth and transport of photosynthates from source to sink organs under low-Zn conditions. Zinc concentrations of both old and young portions of the shoot did not correlate with ZE, but shoot Zn content was found to be significantly correlated with ZE. Furthermore, Zn-efficient genotypes distributed more Zn into young parts of the shoot under Zn-deficient conditions than did the inefficient lines. Variation in seed Zn content did not significantly influence the determination of ZE. We concluded that there is a substantial variation in Zn efficiency in the bean genome, and ZE based on analysis of the young shoot tissues represents a suitable screening technique for the evaluation of ZE in low-Zn soils.