Response of some maize hybrids (Zea mays L.) for foliar application by polyisoprenic on bioactive components grown under middle Egyptian conditions

Grains of three maize hybrids grown in the middle Egypt zone were obtained and investigated for study the effect of spraying treatment with two β-carotene (βC) levels and natural carotenoids extract (NCE). The maize hybrids are yellow hybrid (No. 352) Yellow hybrid (No.178) and High Tec. White(No.2031). Results indicate that the most efficient solvent for carotenoids extraction is boiled methanol whereas the extract weight reached to be 0.913 and 0.9692 g/250 g dry weight grains followed by chloroform and ethanol. Application results of βC and NCE on crude lipids show that yellow hybrid (No. 352) recorded the highest levels followed by yellow hybrid (No. 178) and the lowest levels are recorded in High Tec. White (No. 2130). The concentrations with 7.5 and 15 µg/mL βC are better than NCE. It could be concluded that response of lipids in maize hybrids for foliar application are low. The yellow corn genotypes studied here are characterized with high levels of different isoforms of carotenes and xanthophylls and the results show that the most predominant carotene is β-carotene and the three predominant xanthophyll are zeaxanthin folowed by lutein and β-cryptoxanthin. Total carotenoids in untreated and treated samples ranged from 47.63 to 568.49 µg /g and the highest concentration was recorded with 15 ppm β-carotene as foliar spraying. The Yellow hybrid (No.178) contains higher concentrations from lutein, zeaxanthin, b-cryptoxanthin and b-caotene compared with Yellow hybrid (No.352) and High Tec. White (No.2031). Generally, provitamin A carotenoid constitute 7.65-39.34 % of total carotenoids in maize, whereas zeaxanthin and lutein each commonly represent 30–50 %. Results show that the provitamin A carotenoid compose one third and xanthophyll carotenoids reached to be two thirds. The amounts of provitamin A in traditional yellow maize varieties range from 0.25 μg to 2.5 μg g-1 dry weight. Results obtained here, indicate that spraying with polyisoprenic led to the accumulation of xanthophylls with 60% and carotenes with 40%. The precursors of vitamin A are less and this is due to the genotypes behavior under study which directed to the accumulation of both xanthophylls and carotenes, but the xanthophylls were predominant and higher.