Prediction of nitrogen fertilizer requirement in cotton using petiole and sap nitrate

Abstract

With the aim of refining methods of determining plant N status of cotton, we measured nitrate concentrations in petioles and xylem sap in field experiments over three seasons. Main plots were rotation/tillage treatments which were split for fertilizer N. Petiole nitrate concentration was about 30 g N/kg at appearance of flower buds (squares). Rotation and N rate had highly significant effects on petiole nitrate concentration in every season. There was a linear decline in petiole nitrate with stage of development (measured in day degrees, base 12°C), particularly between 600 and 900 day degrees from sowing.The relationship between fertilizer N requirement and petiole nitrate concentration was exponential, with greatest precision when high fertilizer rates were required. The relationship between fertilizer N requirement and the rate of decline in petiole nitrate was linear, giving equal precision over the N fertilizer range. Optimum plant N status was represented by a petiole nitrate concentration of 21.5 g N/kg at 750 day degrees from sowing, or by a rate of decline in petiole nitrate of 0.0318 g N/kg/day degree. We conclude that the interpretation of petiole nitrate data could be improved by considering the rate of decline in petiole nitrate around flowering, particularly for sites where only moderate amounts of N are required. Concentrations of nitrate in xylem sap were highly correlated with petiole nitrate, but were more variable. For this reason, we concluded that petiole analysis was the superior diagnostic test.

Nitrate and potassium concentrations in cotton petiole extracts as influenced by nitrogen fertilization, sampling date and cultivar

“…Petiole nitrate concentration decreased along the crop season (Table 1) following changes in nitrogen uptake rates due to the variation in crop nutrient requirements (Gerik et al, 1998). Similar results have been obtained under several conditions of soil, cultivars and management practices (Baker et al, 1972;Sunderman et al, 1979;Constable et al, 1991). Significant interactions were observed between sampling time and fertilizer N level, as well as between sampling time and cultivar for the petiole nitrate concentration (Table 1, Fig.…”

“…Models have been developed for estimating desired nutrient levels in petioles for expected yields according to commodity prices and production factor costs (Grimes et al, 1973). The petiole analysis has been used for monitoring N and K nutrition in different cotton regions to optimize nutrient use (Grimes et al, 1973;Lutrick et al, 1986;Constable et al, 1991;McConnell and Mozaffari, 2004;Mozaffari et al, 2005). Petiole N concentration was even useful to study the variation in soil N availability and plant N uptake under different irrigation regimes (Leidi et al, 2001).…”

Early‐Season Plant Nitrate Test for Leaf Yield and Nitrate Concentration of Air‐Cured Burley Tobacco

“…The response of early‐season NO − 3 concentration in the total aboveground plant tissue to applied N was consistent with that of stem and petiole responses observed with other crops (e.g., Constable et al, 1991; Knowles et al, 1991; Roth et al, 1989; Swiader et al, 1988; Westcott et al, 1991). Rather than use specific organs, as was done often for other crops, we sampled the entire aboveground portion of plants for two reasons.…”

“…Total N concentration of burley tobacco leaves sampled between 3 and 5 wk after transplanting appeared to be a better index of leaf yield than extracted chlorophyll or chlorophyll meter readings (MacKown and Sutton, 1998) However, use of these traits to predict corrective N fertilizer needs would require reference plots fertilized with a nonlimiting amount of N to account for the environmental effects and plant developmental variability. Early‐season tissue NO − 3 as a diagnostic test of N sufficiency has not been evaluated in tobacco but has given promising results for several other crops (e.g., Constable et al, 1991; Knowles et al, 1991; Roth et al, 1989; Swiader et al, 1988; Westcott et al, 1991).…”

Revising petiole nitrate sufficiency/deficiency guidelines for irrigated cotton in the Desert Southwest

“…Petiole sampling is point sampling, so it is difficult to characterize large fields, and it does not lend itself to GPS‐guided variable‐rate fertilization. Soil type, cultivar, N rates, plant density, and moisture status all affect petiole NO 3 levels (Constable, Rochester, Betts, & Herridge, 1991; Dahlberg, 1987). Furthermore, petiole NO 3 levels decline during the season at a faster rate than leaf N (Bronson et al., 2001: Muharam et al., 2014).…”