APPRAISAL ON MORPHOMETRY, GAS EXCHANGE CHARACTERISTICS, AND IONS UPTAKE UNDER CADMIUM STRESS IN EARLY- AND LATE-SOWN OF COTTON

Abstract

Cadmium (Cd) is a water-soluble metal pollutant that is not required for plants, but its mobility in the soil-plant continuum has lately attracted substantial interest due to its harmful effects on plants. It may cause serious morphological and physiological abnormalities in addition to inhibiting cotton growth. Thereby, the present study was conducted to explore the effect of different concentrations of Cd on the growth, morphological, biochemical, and physiological processes of cotton (Gossypium hirsutum L.) varieties. Understanding the morphological, biochemical, and physiological responses to Cd stress is necessary for a holistic approach to plant resistance mechanisms to Cd stress. A net house experiment was conducted to investigate the growth and adaptation mechanism of G. hirsutum varieties (V1: KLMNH-142 and V2: KL-FH-886) with different sowing times (i.e., early and late) under Cd stress (250 & mu;M, 500 & mu;M, 750 & mu;M, and 1000 & mu;M). The results showed that Cd predominately accumulated in the root at a higher dose, which consequently led to a reduction in the root biomass. During the late sowing time, transpiration rate (1.01 & PLUSMN; 0.04) and stomatal gas exchange rate (0.01 & PLUSMN; 0.003) were recorded to be significantly decreased by the application of Cd at 1000 & mu;M to variety V2 (KL-MNH886) as compared to the early sowing interval and respective control (1.63 & PLUSMN; 0.06). Calcium contents (1.4 & PLUSMN; 0.5) in the root were decreased in the early sowing period in V1 as compared to the late sowing period. Besides, the application of Cd (1000 & mu;M) has significantly decreased root soluble sugar (0.13 & PLUSMN; 0.001) in V1 under the late sowing period compared with the early sowing period and respective control. Cd not only led to the decrease in root anthocyanin but also changed the chlorophyll content. Our study proved that G. hirsutum has good tolerance to Cd stress during early time intervals as compared to the late time interval and is the best species for soil and ecological environment restoration.