Diagnosis of nitrogen nutrition of flue-cured tobacco with chlorophyll meter

The objective of this study was to evaluate the ability of the chlorophyll meter to estimate chlorophyll and nitrogen content in flue-cured tobacco leaves by correlating chlorophyll meter tested values to extractable chlorophyll and nitrogen during the vegetation period of the consecutive growing seasons under field conditions.Totally three field experiments were conducted in 20032005. Two located in Zhenzhou with four cultivars(NC89,RG17,8504,8541) and same N application rate(51.0 kg/hm2)in 2003,two varieties(Zhongyan101,Yunyan85) and five N levels(30.0,40.5,51.0,61.5,75.0 kg/hm2) in 2004,and the other located in Yuxi with one variety(K326) and five N levels(0,27.0,54.5,81.8,109.0 kg/hm2) in 2005.The results showed that the middle parts of the full expanded leaves were the most optimum position for tobacco nitrogen test by chlorophyll meter.Chlorophyll meter readings varied with year,location,nitrogen application rates,leaf position at the stem,part of leaf.There were a significant positive relationship between chlorophyll meter readings,chlorophyll content and total nitrogen of leaf.The determination coefficient of chlorophyll meter readings and chlorophyll content,value of SPAD-502 and CCM-200 was 0.8755(P0.001) and 0.9455(P0.001),respectively.The regression equation of SPAD value(SPAD) and total nitrogen(N) of leaf was N=0.0265SPAD+0.9601(R2=0.7649,P0.001) which fitting effect between the formula and the test results was good,thus,which means that the instruments can be used for evaluating nitrogen nutrition of tobacco plants.