Chlorophyll Measurements and Nitrogen Nutrition Index for the Evaluation of Corn Nitrogen Status

Abstract

Plant-based diagnostic techniques are used to determine the level of crop N nutrition but there is limited comparative research on the diff erent methods. Our objectives were to establish the relationship between chlorophyll meter (CM) readings and N nutrition index (NNI) during the corn (Zea mays L.) growing season, and to compare both methods as diagnostic tools for predicting grain yield response to N fertilization. Th e study was established at eight site-years using four to seven N fertilization rates. Th e CM readings from the youngest collared leaf were taken on fi ve to eight sampling dates in 2004, 2005, and 2006 along with NNI determinations. Generally, CM readings and NNI increased with increasing N rates. Chlorophyll meter readings and relative CM (RCM) readings were related to NNI, but the intercepts and/or slope of the response curves varied with site-year. Because they are site-specifi c, these relationships may not be reliable indicators of corn N status. Th e relationship between CM readings and relative grain yield (RY) at stage of development ≈V12 was also site-specifi c. Relative CM readings (RY = −0.64 + 1.65 RCM if RCM ≤ 0.98 and RY = 0.97 if RCM > 0.98; R 2 = 0.60) and NNI (RY = −0.34 + 1.47 NNI if NNI ≤ 0.88 and RY = 0.96 if NNI > 0.88; R 2 = 0.79) at stage of development ≈V12 were related to RY. Th ese two relationships were stable across site-years and could be used to detect and quantify N defi ciencies of corn.

SPAD Values and Nitrogen Nutrition Index for the Evaluation of Rice Nitrogen Status

“…NNI was positively related to SPAD values. The increase in NNI with increasing N fertilization has been previously reported in corn (Plénet and Cruz, 1997;Ziadi et al, 2008) and in wheat (Debaeke et al, 2006;Prost and Jeuffroy, 2007). This positive relationship varied across different developmental stages and leaf positions.…”

“…The non-linear relationship between SPAD values and NNI has been proved in fescue (Errecart et al, 2012), corn (Ziadi et al, 2008), wheat (Vouillot et al, 1998;Prost and Jeuffroy, 2007) and cocksfoot (Duru, 2002), and the correlation of RSPAD values with NNI, and relative grain yield has been studied only in corn (Ziadi et al, 2008) and wheat (Debaeke et al, 2006). Debaeke et al (2006) also found that the non-linear relationship between RSPAD values and NNI was not significantly affected by years, genotypes, and developmental stages.…”

Effect of Nitrogen Addition and Weed Interference on Soil Nitrogen and Corn Nitrogen Nutrition

“…The NNI was also shown to be a reliable predictor of corn relative yield (Ziadi et al 2008b). Weed interference had a relatively small affect on soil NO 3 -N, but a relatively large affect on NNI, primarily as the result of the large influence of weed interference on corn growth.…”

“…A simple nondestructive diagnostic tool would be considerably more convenient for practitioners. Several authors have shown that measured NNI was highly correlated to the normalized index obtained from measurements made with the SPAD 502 chlorophyll meter, which provides a rapid, nondestructive estimate of relative leaf chlorophyll content (Debaeke et al 2006;Ziadi et al 2008b). If the SPAD meter can be used to predict NNI reliably, it may also be a useful tool for assessing the relative impact of weeds on crops.…”

Tolerance of the annual legumesBiserrula pelecinus,Ornithopus sativa,Trifolium spumosum,T. vesiculosumandT. subterraneumto soil acidity

“…Leaf chlorophyll content was assessed in the current experiment as a non-destructive method for the N status in plant shoots (Byju & Anand 2009). Ziadi et al (2008) reported that the relationship between chlorophyll meter readings and N nutrition index was stable across site and years, and could be used to detect and quantify N deficiencies in maize. In the current study, significant relationships were established between chlorophyll readings and shoot weight, soil-exchangeable Al% and pH values 35 days after sowing (Table 6).…”