Good afternoon everyone, Today I want to present a simple question: Can we improve the Nitrogen Use Efficiency in Maize Production?
How Maize NUE can be improved?Two main components, N uptake efficiency (N uptake/N from soil) and N utilization efficiency (yield/N uptake)
The relationship between the N uptake and the leaf area accumulation is at 1:2 (50% of N uptake and 100% of leaf area) at the R1 stage. So, why we are looking this ratio at silking time? Mainly because the final kernel number is defined at this phenological stage…. And this parameter has a high correlation with yields….
Maize Leaf Area production is highest and reaches the maximum point (peaked) at R1- Flowering or Silking time. On the other hand, N uptake attains around 40-60% of the total N accumulation at the same phenological stage.
First, we can affirm that the N uptake and leaf area ratio is not constant across N rates and plant densities,Second, the ratio is lower as N rates decreases and plant density increases; Moreover, in overall, the ratio is quite low at the 0N treatment
Transcript
1. Can we improve the Nitrogen Use Efficiency in Maize Production?Maize leaf area and N uptake at different plant densities and N rates<br />Ignacio A. Ciampitti<br />AGRY 596 – Professional Presentation<br />Purdue University - Department of Agronomy<br />September 22, 2010<br />
2. Introduction<br />NUE, defined as the grain yield per unit of N available from the soil, including N fertilizer<br />Why NUE is important?<br />Right N rate applied, both economically and environmentally important. <br />Why Maize NUE is so low?<br /><ul><li>Total loss of fertilizer N ranged from 20 to 50%, attributed to the combined effects of denitrification, volatilization and/or leaching.</li></ul>Why N is important?<br /><ul><li>N uptake evolution follows the dry matter accumulation</li></li></ul><li>Nitrogen in the Life of the Corn Plant<br />100<br />80<br />60<br />40<br />20<br />0<br />100<br />75<br />50<br />25<br />0<br />~100%<br />N<br />~50%<br />Percent of total N taken up by plant<br />Percent of Maximum Leaf Area <br />Silking<br />Dry Weight<br />Highest Leaf Area<br />0 25 50 75 100 115<br />Days after Planting (Mid-Season Corn Belt Hybrid)<br />
3. Understanding the leaf area and N uptake relationship<br />Management factors<br />Environment<br />Plant density<br />Leaf Area<br />Maize Yield<br />N uptake<br />Nitrogen rate<br />NUE<br />Nitrogen rate<br />
4. Presentation Question<br />Is the ratio of N uptake to leaf area constant when both are affected by plant density and N rate?<br />
6. Concluding remarks<br /><ul><li>The strategy of the maize crop is to maintain the leaf area expansion even under N deficiency situations.
7. The accumulation of N per unit of leaf area decreases as N rate decreases and plant density increases.
8. The ratio of the N uptake to leaf area is not constant, and it varies with the N rate and plant density factors.
9. More knowledge about maize physiology and N uptake dynamics will be needed to improve the NUE.</li></li></ul><li>Thanks! Questions?<br />
10. Introduction<br />How Maize NUE can be improved?<br /><ul><li>Two main components, N uptake efficiency (N uptake/N from soil) and N utilization efficiency (yield/N uptake)</li></ul>Why N is important?<br /><ul><li>N uptake evolution follows the dry matter accumulation</li></li></ul><li>Maize Phenological Stages<br />Physiological Maturity<br />V14 <br />Phenological Stages<br />Silking<br />R6 <br />R3<br />V9<br />R1 <br />R3<br />Yields= Kn*Kw<br />Kernel Number (Kn)<br />V6<br />R3<br />V4<br />Kernel Weight<br />(Kw)<br />Germination<br />Planting<br />Critical Period for Kernel Determination<br />
11. Materials and Methods<br />Experimental Setup:<br />Year: 2009<br /> Locations: Purdue University Agronomy Center for Research and Education (ACRE) and at the Pinney Purdue Agricultural Center (PPAC) near Wanatah, IN<br /> Layout:<br /><ul><li> Split-split Plot Design
14. 9 m Row-1</li></ul> Tillage: Fall Strip-tillage <br /> Starter Fertilizer: 25 kg/ha Urea<br />Treatments:<br />Hybrid (main plot):<br /><ul><li>Mycogen 2T780 (non-RW) and 2T787 (RW) at ACRE
15. Mycogen 2M749 (non-RW) and 2M750 (RW) at PPAC</li></ul>Plant density (subplot):<br />54,000 plants ha-1 (agronomic sub-optimal)<br />79,000 plants ha-1 (≈ agronomic optimal)<br />104,000 plants ha-1 (agronomic supra-optimal)<br />Side-dress nitrogen (N) rate (28-0-0) (sub-subplot):<br />0 kg N ha-1<br />165 kg N ha-1 (V3) (≈ agronomic optimal N rate)<br />330 kg N ha-1 [V3, V5 (equal split)]<br />
16. Materials and Methods<br />Shoot Biomass and N uptake:<br /><ul><li>Measured at four stages (V14, R1, R3 and R6)
17. 6 consecutives plants from three replications
18. Different fractions were determined and weighed after separation (stem and leaves at V14, ear and shoot biomass at R1, R3 and R6)
19. Drying at 60 °C until plant dry weights were stable. Sub-samples were ground for subsequent nutrient concentration analysis by A&L Laboratories</li></ul>Leaf Area Index:<br /><ul><li>Estimated from the relationship between length and width of largest leaves from tagged plant
20. Total Leaf Area observed from the harvested plants at R1</li></li></ul><li>Nitrogen use efficiency in maize plants: Does shoot growth potential drive N uptake?<br />In the N fertilized treatments , the stem N concentration was greater compared with the zero N.<br />The stem N concentration declines as shoot biomass increases, as a results of the “N dilution effect”.<br />N fertilized treatments :<br />Shoot Biomass<br />Stem N uptake<br />Zero N treatment :<br />Stem N uptake<br />Shoot Biomass<br />
21. Which will be the best parameters for NUE selection in maize?<br />At equivalent LAI, the N treatments get a bigger ear biomass and the predictability increased (higher R2).<br />Low plant population= Low LAI<br />Ear biomass with N applied<br />N fertilized treatments :<br />Leaf Area Index<br />Stem N uptake<br />Zero N treatment :<br />Stem N uptake<br />Leaf Area Index<br />
22. Which will be the best parameters for NUE selection in maize?<br />In the N treatments , as stem N uptake before flowering increases maize productivity increases<br />In the zero N, the poor N status limited the potential maize yield that can be achieved.<br />N fertilized treatments :<br />Ear biomass<br />Stem N uptake<br />Zero N treatment :<br />Stem N uptake<br />Ear biomass<br />
23. Conclusions<br />1.Pre-silking stem N uptake and leaf area index at R1 seem to be important parameters to predict potential dry matter response to nitrogen fertilizer regardless plant density and hybrids (under low RW incidence). <br />2. In N fertilized treatments, shoot growthappears to drive N uptake in maize plants; however, without N fertilizer other factors could be more important.<br />3. These physiological parameters, specifically pre-silking stem N uptake, could be taken into consideration for nitrogen use efficiency breeding programs.<br />
24. Materials and Methods<br />Per-plant Measurements (partial list):<br />Plant available space<br />Plant height (V5, V14, R1)<br />Sixth-internode maximum stem diameter (V14, R1, R3, R6)<br />Leaf chlorophyll/N content (i.e., SPAD)(V14, R1, R3, R5)<br />Largest leaf length, width, and area (R1)<br />Total green leaf area (R1)<br />Green leaf area index (LAI) (R1)<br />Total leaf number and evolution<br />Anthesis and silking date<br />Aboveground total biomass (V14, R1, R3 and R6) <br />Kernel number<br />Individual kernel weight<br />Grain weight<br />Harvest index<br />Canopy-level Measurements (partial list):<br />Leaf chlorophyll/N content (i.e., SPAD)(V14; R1, R3, R5)<br />Machine harvest grain yield<br />
25. Weather Conditions<br />2009<br />(d)<br />
26. Results: N uptake Evolution <br />The greatest N response was higher in low density in per plant analysis, and in per area basis, the highest response was observed at the high density or plant population treatment (from 50 to 100 kg N/ha).<br />
27. Leaf Area Index (LAI) Evolution<br />The LAI was greatest in the high plant population treatment regardless hybrids and the N treatments (medium and high N rate).<br />The LAI declining trends observed were affected more by the population factor than by N rates- independent of the hybrids at both locations.<br />
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