Effects of shade net in different colors on cigar tobacco growth and quality of wrapper leaves

【Objective】 The aim of the study was to explore the effects of shade nets in different colors on the growth and quality of Yunxue 2 cigar tobacco， which could provide theoretical basis for selecting appropriate shading materials in the production of domestic cigar tobacco raw materials and improving the quality of tobacco leaves. 【Method】 Using Yangzhi （without shade net） as the control （CK）， this study investigated the effects of 4 shade net colors， namely white （T1）， silver （T2）， gray （T3）， and gray black （T4）， and the shade net was erected 10 d after transplanting. The average light intensity during the growth period of tobacco plants under different treatments was measured. Agronomic traits of the tobacco plants were investigated 7 d after topping， and the physical properties， chemical components， appearance quality， and neutral aroma components contents of the fermented tobacco leaves were determined to compare and analyze the effects of shade net in different colors on the growth and quality of wrapper leaves. 【Result】 Compared with CK， the light intensity in T1， T2， T3， and T4 decreased by 23.26%， 45.54%， 46.31%， and 51.22% respectively. Shade net treatments improved the agronomic traits of wrapper leaves， including leaf length， leaf width， and leaf area. Among them， both leaf width and leaf area were the highest in T1， showing significant increases of 19.51% and 57.61% respectively compared to CK（P<0.05， the same below）. In the physical properties of the wrapper leaves after drying， as the color of the shade net deepened， the leaf width of the four shade net treatments first decreased and then increased， while leaf density and leaf surface thickness gradually decreased. In the chemical components， the contents of reducing sugar， total nitrogen， total sugar-reducing sugar ratio， nitrogen-nicotine ratio， and potassium-chlorine ratio in the tobacco leaves of the four shade net treatments were significantly higher than those of CK， while the nicotine and chlorine contents were significantly lower than those of CK； in the appearance quality， the maturity， oiliness， body， integrity， and luster scores of the tobacco leaves of four shade net treatments were all better than those of CK， and the comprehensive score was the highest in T1 （67.33 points）. The determination results of neutral aroma components contents showed that the total amounts of chlorophyll degradation products， carotenoid degradation products， and neutral aroma substances were superior in T1. 【Conclusion】 In the production of Yunxue 2 cigar tobacco leaves， the use of white shade nets is beneficial for improving the physical structure of the tobacco leaves， optimizing the proportion of key chemical components， and increasing the content of neutral aroma components. It can be regarded as an important regulatory measure for enhancing the appearance quality and quality of cigar tobacco.