The effect of potassium nitrate on the uptake and translocation of foliar-applied nutrients in plants Harmen Tjalling HOLWERDA Agronomy Committee Potassium Nitrate Association (PNA) 1
Contents Trials about the effect of potassium nitrate (KNO 3 ) on the uptake and translocation of foliar-applied: zinc and magnesium fertilizers in wheat and maize (year 2016). zinc, iron and magnesium fertilizers in wheat and soybean (year 2017). Latest information about PNA. General conclusion. 2
Responsible researcher and institute Trials are conducted by Prof Dr Ismail Cakmak and his team. Sabanci University, Istanbul, Turkey. 3
Introduction Foliar nutrient salts sprays, based on nitrate as opposed to sulphate, are generally accepted to be the most efficient in terms of both anion and cation uptake by the leaf and translocation within the plant, because: Smaller sized Single charged NO 3-1 SO 4-2 Zn, Mg, Mn and Cu are mainly spray-applied as sulphated salts. Once fertilizer salts are dissolved in water, all nutrients are present in their ionic form. 4
Research question and hypothesis Research question: Could nutrient uptake by the leaf and translocation within the plant be improved by adding a nitrate source to the spray tank solution which also contains sulphated nutrient salts? Hypothesis: H 0; null : NO (no positive effect of KNO 3 ) H alternative : YES (a positive effect of KNO 3 ) 5
Introduction - Hypothesis Foliar fertilizers Spray tank Hypothesis Leaf spray 6
Introduction - Hypothesis Foliar fertilizers Spray tank Zn 2+ SO 4 2- Hypothesis Leaf spray 7
Introduction - Hypothesis Foliar fertilizers Spray tank K + NO 3 - K + NO 3 - Zn 2+ SO 4 2- Hypothesis Leaf spray 8
Introduction - Hypothesis Foliar fertilizers Spray tank K + NO 3 - K + NO 3 - Zn 2+ SO 4 2- Hypothesis Leaf spray NO 3 - NO 3 - Zn 2+ 9
2016 - Research Phase I In 2016, three trials were conducted in wheat and maize. 10
T1A Young wheat leaves immersed in Zn or Mgcontaining nutrient solution + KNO 3 Leaf immersion in the treatment solution of two weeks old plants for about 10 seconds (1X in the morning, and 1X in the late afternoon) over 4 days. Plants were grown in a calcareous clay loam soil. ± Calc clay loam soil 11
T1A Young wheat leaves immersed in Zn or Mgcontaining nutrient solution + KNO 3 Treatment Zn- or Mg-salts with and without KNO 3. Rate sprayed or treated Zn-treatment Without or with 2% KNO3 - Control - 0,20% ZnSO4.7H2O - 0,33% Zn-EDTA - 0,18% Zn(NO3)2.6H2O - - Control + 0,20% ZnSO4.7H2O + 0,33% Zn-EDTA + 0,18% Zn(NO3)2.6H2O + Rate sprayed or treated Mg-treatment Without or with 2% KNO3 - Control - 2,00% MgSO4.7H2O - 2,08% Mg(NO3)2.6H2O - - Control + 2,00% MgSO4.7H2O + 2,08% Mg(NO3)2.6H2O + 12
Main result: Adding KNO 3 to the treatment solution clearly promoted Zn uptake and transportation to the untreated shoot part in all tested Zn fertilizers, especially in case of Zn-EDTA. Rate sprayed or treated T1A leaves immersed in Zn containing nutrient solution + KNO 3 Zn-treatment 2% KNO3 Relative difference without with % Zn-concentration (mg/kg) in the untreated shoot part Stat sign at P=0,05 - Control 13 13 +5-0,20% ZnSO4.7H2O 20 25 +27 * 0,33% Zn-EDTA 16 29 +76 * 0,18% Zn(NO3)2.6H2O 17 21 +22 * Highest 13
T1B Young wheat leaves immersed in Zn or Mgcontaining nutrient solution + KNO 3 Leaf immersion in the treatment solution of two weeks old plants for about 10 seconds (1X in the morning, and 1X in the late afternoon) over 4 days. Plants were grown in a nutrient solution. ± 14
T1B Young wheat leaves immersed in a low Zn containing nutrient solution + KNO 3 Main result: Adding KNO 3 to the treatment solution clearly promoted Zn uptake and transportation to the untreated shoot part in case of Zn-EDTA. Rate sprayed or treated Zn-treatment 2% KNO3 Relative difference without with % Zn-concentration (mg/kg) in the untreated shoot part Stat sign at P=0,05 - Control 23 23 +0-0,20% ZnSO4.7H2O 31 34 +8 * 0,33% Zn-EDTA 37 47 +26 * 0,18% Zn(NO3)2.6H2O 32 31-3 - Highest 15
T2 Maize leaf uptake and translocation of Zn or Mg-containing foliar spray sol. + KNO 3 Whole shoot of plants has been sprayed with Zn or Mg fertilizers. During the spray, the shoot tip + most youngest leaf + soil surface were covered to avoid contamination from the sprays. 1 2 3 16
T2 Maize leaf uptake and translocation of Zn or Mg-containing foliar spray sol. + KNO 3 Treatments: Zn- or Mg-salts with and without KNO 3, as in T1. 17
Main result: Adding KNO 3 to the treatment solution promoted Zn uptake and transportation to the untreated shoot part in case of Zn-EDTA and Znnitrate (although Non Significant). Rate sprayed or treated T2 Maize leaf uptake and translocation of Zncontaining foliar spray sol. + KNO 3 Zn-treatment 2% KNO3 Relative difference without with % Zn-concentration (mg/kg) in the untreated shoot part Stat sign at P=0,05 - Control 11 12 +2-0,20% ZnSO4.7H2O 29 28-1 - 0,33% Zn-EDTA 24 30 +23-0,18% Zn(NO3)2.6H2O 38 44 +16 - Highest 18
T3 Wheat grain Zn or Mg conc. after Zn or Mgcontaining foliar spray sol. + KNO 3 Soil-grown, potted wheat plants have been sprayed with Zn or Mg fertilizers. Sprayed twice: at heading and early milk stages. 19
T3 Wheat grain Zn or Mg conc. after Zn or Mgcontaining foliar spray sol. + KNO 3 Treatments: Zn- or Mg-salts with and without KNO 3. Similar to T1: Zn 25% higher; Mg identical. 20
Main result: Adding KNO 3 to the treatment solution did not promote grain Zn concentration in none of the tested Zn fertilizers. Reason: plants had already high grain Zn with foliar Zn-treatment without KNO 3, which may have masked the benefit of KNO 3 addition to the spray. Rate sprayed or treated T3 Wheat grain Zn conc. after Zn-containing foliar spray sol. + KNO 3 Zn-treatment 2% KNO3 Relative difference without with % Grain Zn-concentration (mg/kg) Stat sign at P=0,05 - Control 9 9 +1-0,25% ZnSO4.7H2O 45 45-0 - 0,41% Zn-EDTA 30 31 +5-0,22% Zn(NO3)2.6H2O 45 47 +4 - Highest 21
T1-T3 Main conclusions Zn trials Zn-treatment T1A T1B T2 T3 Crop Wheat Maize Wheat Application Leaf immersion Spray 2 sprays (heading + early milk stage) Root medium soil solution soil soil Observed Leaf Zn concentration Grain Zn conc Relative difference (%) between with and without 2% KNO3 Control +5_ +0_ +2 +1 ZnSO4.7H2O +27* +8* -1-0 Zn-EDTA +76* +26* +23 +5 Zn(NO3)2.6H2O +22_ -3_ +16 +4 22
T1-T3 Main conclusions Mg trials Zn-treatment T1A T1B T2 T3 Crop Wheat Maize Wheat Application Leaf immersion Spray 2 sprays (heading + milky stage) Root medium soil solution soil soil Observed Leaf Mg concentration Grain Mg conc Relative difference (%) between with and without 2% KNO3 Control +2_ -0_ +0-8 MgSO4.7H2O -8* +12* -5-1 Mg(NO3)2.6H2O -9* +5* +0-0 Inconsistent effects. This absence of KNO 3 effect may be linked to the relatively low dose rate of Mg fertilizers (2% conc) applied to the crops. 23
General conclusion H 0 rejected. H alternative is accepted The addition of potassium nitrate to the spray tank solution does promote the uptake and translocation of foliar-applied sulphated (as well as nitrate-based and chelated) nutrients in plants. 24
2017 - Research Phase II Effects of KNO 3 on leaf absorption and transportation of foliar-applied zinc, iron and magnesium in wheat and soybean: T1: Leaf uptake and transport of Zn and Fe, and correction of leaf chlorosis in soybean, grown in Zn- or Fe-deficient soil Zn-EDTA, Zn-nitrate, and Zn-sulphate; Fe-EDTA and Fe-sulphate. T2: Leaf uptake and transport of Mg, and correction of Mg-deficiency chlorosis in wheat, grown under low Mg supply Mg-sulphate, Mg-nitrate. 25
2017 - Research Phase II Effects of KNO 3 on leaf absorption and transportation of foliar-applied zinc, iron and magnesium in wheat and soybean: T3: Shoot transport and grain accumulation of Zn and Mg in wheat plants, grown in soil medium under greenhouse conditions Compared to 2016 trials: lower Zn conc; higher Mg fertilizer conc (4%). T4: Shoot transport and grain accumulation of Zn and Mg in wheat plants under field conditions. 26
PNA website UK, CN, ES, PT, (FR) www.kno3.org 27
PNA Website - scientific library 160 abstracts in English, Spanish, Chinese crop applic theme key word 28
PNA library news E-mail blast 2 articles/30 days 29
PNA website (m.kno3.org) Easy reading on mobile device 30
General conclusion: Potassium nitrate is a versatile source of K and N! 1. Plant nutrition salinity and drought stress relief; when nitrate (NO 3 ) is preferred or excess ammonium (NH 4 ) unwanted. 2. Bud break and flowering induction. 3. Enhancer of foliar nutrient uptake and translocation. New! Thank you! 31