Possible Use of the Chlorophyll Meter for Diagnosing Nitrogen Deficiency in Early Growth Stage of Tobacco under Field Condition

Nitrogen is one of the most essential nutritional element in growth and a determining factor in tobacco yield. Therefor, rate and timing of nitrogen application is very important for growth of this plant. The purpose of this study is to use SPAD values to estimate nitrogen usage through correlation of SPAD value with yield and quality traits at different growth stages of tobacco. This study was conducted in a randomized complete block design on flue cured tobacco (K-326 cultivar) in Tirtash Tobacco Research and Education Center for two years (2015 and 2016). Treatments consisted of three nitrogen level (20, 40 and 60 kg.ha-1) and three application methods of nitrogen (1- two parts of nitrogen broadcasted before planting + one part of nitrogen as side dressing, 2- one part of nitrogen before planting + one part as first side dressing + one part as second side dressing, 3- two parts of nitrogen fertilizer as strip application + one part as side dressing) and a control (without fertilizer treatment). Chlorophyll meter (SPAD-502) was used in 40, 50 and 60 days after planting for greenness of lower, middle and upper leaves and various parts of the leaves (top, middle and bottom). During the growing season, length and width of upper, middle and lower leaves, green and dry leaf weights, average price and gross income were determined. The results showed that green and dry leaf weights were increased by increasing nitrogen application and this was significant at %1 probability level. The highest correlation between SPAD value and upper leaves yields of 40 days transplanting was R2=0.86 and middle leaves yield after 50 days of transplanting was R2=0.89 which were the best leaves for estimating tobacco nitrogen usage. Average price of tobacco was decreased as nitrogen use increased and highest gross income was obtained by using 20 kg nitrogen with 3 split applications