Investigating the role of different maize (Zea mays L.) cultivars by studying morpho-physiological attributes in chromium-stressed environment.

Abstract

Because of global land surface warming, heavy metal toxicity is expected to occur more often and more intensely, affecting the growth and development of the major cereal crops such as maize (Zea mays L.) in several ways, thus affecting the production component of food security. Hence, it is important to know the best cultivars of Z. mays in abiotic stress environment to fulfill the market demand of this staple food. For this purpose, we investigate the present study to find the best Z. mays cultivar to be grown in chromium (Cr)-contaminated sand (200µM). In this experiment, we have studied 10 cultivars (Malka, Sadaf, Pearl, CZP, YY, YH, MMRI-yellow, Sahiwal, EV-20, and EV-77) of Z. mays grown in plastic pots for 4weeks (in addition with seed germination) under Cr - (0µM) and Cr + (200µM) in sand medium. Based on the findings of the current experiment, we illustrated that Cr toxicity induced a significant (P < 0.05) reduction in shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight and root dry weight, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid content and induced oxidative damage to membrane-bounded organelles by increasing the malondialdehyde and hydrogen peroxide which were manifested by flavonoid and phenolic contents. Moreover, Cr uptake was also higher in the plants grown in the Cr-contaminated sand compared to the plants grown without the Cr-contaminated sand. We also noticed that Pearl, CZP, and Sahiwal cultivars are suggested to be Cr-tolerant cultivars as showed better growth and development in Cr-contaminated sand while Sadaf, MMRI, and EV-77 showed lower growth and composition in Cr-contaminated sand. The overall pattern of Z. mays cultivars grown in Cr-contaminated sand is as follows: Pearl > CZP > Sahiwal > YY > YH > EV-20 > Malka > EV-77 > MMRI-yellow > Sadaf. Conclusively, it can be identified that when grown in Cr-contaminated sand, Pearl, CZP, and Sahiwal have greater ability to grow in polluted soils. Overall, Z. mays cultivars showed better growth in Cr-stressed environment due to defense mechanism but further experiments needed to be conducted on molecular level.