Nitrate-Nitrogen Sufficiency Ranges in Leaf Petiole Sap of Brassica oleracea L., Pac Choi Grown with Organic and Conventional Fertilizers

Abstract

<jats:p>Greenhouse experiments were conducted to determine the response of <jats:italic>Brassica oleracea</jats:italic> L., pac choi to fertilizer rates and sources and to establish optimal soluble nitrogen (N) application rates and nitrate meter sufficiency ranges. Conventional soluble fertilizer was formulated from inorganic salts with a 4:1 NO<jats:sub>3</jats:sub>-N:NH<jats:sub>4</jats:sub>-N ratio. Phosphorus (P) was held at 1.72 m<jats:sc>m</jats:sc> and potassium (K) at 0.83 m<jats:sc>m</jats:sc> for all treatment levels. The organic soluble fertilizer, fish hydrolyzate (2N–1.72P–0.83K), was diluted to provide the same N levels as with conventional treatments. Both fertilizers were applied at N rates of 0, 32, 75, 150, 225, 300, and 450 mg·L<jats:sup>−1</jats:sup>. Seedlings were transplanted and fertilizer application began at 18 days. Plants were harvested at 7 weeks (5 weeks post-transplanting) after receiving 15 fertilizer applications during production. Samples of the most recently matured leaves were harvested weekly and analyzed for petiole sap NO<jats:sub>3</jats:sub>-N and leaf blade total N concentration. Leaf count, leaf length, and chlorophyll content were also measured weekly. Fresh and dry weights were determined on whole shoots and roots. Optimum yield was achieved at the 150-mg·L<jats:sup>−1</jats:sup> fertility rate with both conventional and organic fertilizers. Field and high tunnel experiments were conducted to validate the sufficiency ranges obtained from the greenhouse studies. Sufficiency levels of NO<jats:sub>3</jats:sub>-N for pac choi petiole sap during Weeks 2 to 3 of production were 800 to 1500 mg·L<jats:sup>−1</jats:sup> and then dropped to 600 to 1000 mg·L<jats:sup>−1</jats:sup> during Weeks 4 through harvest for both conventional and organic fertilizers sources. Total N in leaf tissue was less responsive to fertilizer rate effects than petiole sap NO<jats:sub>3</jats:sub>-N. Chlorophyll content was not useful in evaluating pac choi N status. These guidelines will provide farmers with information for leaf petiole sap NO<jats:sub>3</jats:sub>-N to guide in-season N applications.</jats:p>

Relation between soil solution composition and petiole cellular extract of crops in western Mexico

“…In lettuce crops, maximum values of 225-267 mg L -1 were recorded. These values are higher than the optimum found in some brassicas (150 mg L -1 ) (Altamimi et al, 2013). The wide variability observed in nitrate concentrations in this study may be due to imprecise applications of nitrogen fertilizers or, to their excessive amounts, which frequently incur in high lixiviation.…”

“…Castellanos et al (1999) reported values between 600 to 900 mg L -1 in vertisol-type clay loam soils in the central region of Guanajuato, Mexico; high yields of broccoli are achieved in this place. Altamimi et al (2013) observed optimal yields at levels of 13 to 123 mg L -1 . The low content of K in SS recorded in some crops may be due to the low retention of this element by the soil.…”

Effect of Nitrogen Source on Pac Choi (Brassica rapa L.) Chemistry and Interactions with the Diamondback Moth (Plutella xylostella L.)

“…To maintain uniform growing medium moisture across the blocks, an additional pac choi pot was placed at the corner of each bench, which served as an indicator container to determine when watering was needed. Pac choi plants received 750 mL of deionized water when the gravimetric weight of the indicator pots decreased by 30% from container capacity (Altimimi, 2010;Gardner, 1965) in adjacent blocks. Temperature and relative humidity were recorded using a HOBO data logger (Onset Computer Corp., Pocasset, MA) set at 30-min intervals.…”

“…The eight plants within each block were randomly assigned to receive either an organic or conventional fertilizer treatment (four organic and four conventional). The organic fertilizer was a soluble fish hydrolysate (Neptune's Harvest, Gloucester, MA) labeled as a 2.2N-4.3P-0.3K fertilizer and diluted to obtain a target concentration of 167 ppm N. This N concentration was selected based on previous greenhouse experiments associated with optimal N rates and pac choi yield (Altimimi, 2010). Three 100-mL diluted hydrolysate samples were submitted for nutrient testing [total N, total phosphorus (P) by potassium (K) persulfate digest, NO 3 --N, and NH 4 + -N in filtered samples by colorimetric analysis and P, K, Mg, sulfur (S), iron (Fe), sodium, and chlorine (Cl) in filtered samples analyzed by inductively coupled plasma spectroscopy] by the Soil Testing Laboratory at Kansas State University (Manhattan, KS).…”

Evaluation of real-time nutrient analysis of fertilized raspberry using petiole sap

“…Petiole sections were placed into a plant press (Zyliss, Farnborough, United Kingdom), manually pressed for approximately 10 s using consistent pressure, and approximately 20 drops of sap were collected into a 5 ml beaker. The sap was not diluted and followed approaches outlined in previous studies (Folegatti et al, 2005;Altamimi et al, 2013;Carson et al, 2016). Extracted sap was analyzed for NO 3 − , K + , and Ca 2+ concentrations using compact ion meters with ion selective electrode sensors (Horiba LAQUAtwin; Spectrum Technologies, Aurora, IL, United States).…”