Abstract

ZAVALA ESTRADA, Fabiola et al. Leaf Morphological and Physiological Changes of Tolerant and Susceptible Bean Genotypes to Iron Deficiency. Terra Latinoam [online]. 2011, vol.29, n.3, pp.267-276. ISSN 2395-8030.

The iron (Fe) chlorosis is an abiotic stress mainly found in crops growing on calcareous or alkaline soils, and the degree of morphological and physiological alteration deepens on genotype tolerance to Fe deficiency. In tolerant and susceptible bean (Phaseolus vulgaris L.) genotypes to iron deficiency some morphological and physiological changes (SPAD readings, net photosynthesis, nutrient concentration) in leaves were detected when plants were exposed to Fe deficiency in order to identify the gradual response of both bean genotypes. In the chlorotic leaf of the tolerant genotype the structure of mesophyll was organized but with the spongy parenchyma more compacted and less and smaller chloroplasts than in the green leaf. In the chlorotic leaf of the susceptible line the mesophyll structure was disorganized, with irregular cells in form and size and resembling absence of chloroplasts. In chlorotic leaves of both genotypes, there was a small development of thylakoids and therefore there was no formation of grana. Independently of Fe supply and pH media the tolerant Fe chlorosis genotype showed higher SPAD readings and photosynthetic rate than the susceptible genotype. Higher net photosynthesis was reached with 0.5 and 2 mg L-1 of Fe with the tolerant genotype (12.33 μmol CO2 m-2 s-1) and susceptible (10.62 μmol m-2 s-1 CO2), respectively. The tolerant genotype presented higher concentration in leaf of K and the susceptible genotype showed higher concentration of Ca, Cu, and Zn. The Fe concentration showed an increase as Fe increased in the nutrient solution and it decreased with pH 8.5, and Cu and Zn concentration also decreased.

Keywords : Phaseolus vulgaris; iron deficiency; chloroplasts; photosynthesis; nutrimental concentration.

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