Effect of water and nitrogen regulation on the appearance quality of marigolds

Abstract

This study was carried out at the Yimin Irrigation Experimental Station in Minle County, aiming to investigate the effects of water and nitrogen regulation on the appearance and nutritional quality of pigmented marigolds under drought conditions. The experiment was conducted by drip irrigation under membrane, with 10 treatments (including the control group CK), divided into four fertility stages, namely, seedling stage, bud stage, early flowering stage and full flowering stage through randomized block group design, with three gradients of soil moisture (moderate water deficit W1, mild water deficit W2, and full irrigation W3), and four levels of nitrogen application (low nitrogen N1, medium nitrogen N2, high nitrogen N3, and the local nitrogen level CK), to analyze the effects of different treatments on the appearance and nutritional quality of the main inflorescence of marigolds. The effects of different treatments on the OD of main inflorescence and lutein content of marigold were analyzed. The results showed that the effect of irrigation water amount on lutein content of marigold was highly significant (P<0.01), the effect of nitrogen application was significant (P<0.05), while the interaction effect of water and nitrogen was not significant (P>0.05). In terms of appearance quality, the W2N2 treatment (mild water deficit and moderate nitrogen application) had the largest main inflorescence OD, which increased by 4.21% compared to the control, while in terms of nutritional quality, the W2N2 treatment had the highest lutein content (20.88 mg·g-1), which increased by 0.21% compared to the control. The combination of moderate water deficit and moderate nitrogen application significantly improved the appearance and nutritional quality of marigold.