Breeding for improved nitrogen use efficiency in oilseed rape. Pete Berry.

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1 Breeding for improved nitrogen use efficiency in oilseed rape Pete Berry

2 Breeding oilseed rape with a low requirement for nitrogen fertiliser (LK0979) Elsoms Seeds

3 N use efficiency in oilseed rape Oilseed rape Wheat Rate of N fertiliser (kg N/ha) Yield (t/ha) Dry matter in seed (kg/kg N) Energy in seed (MJ/kg N) Energy in straw (MJ/kg N) Total energy (MJ/kg N)

4 Variety trials with & without nitrogen

5 Variety trials High N Yield Low N yield Yield (t/ha) Mean of 6 site seasons Variety x N SED = 0.13 t/ha Variety

6 % of yield lost at low N Variety % of yield lost at low N

7 Effect of higher yielding varieties kg N/ha 4.0 Yield (t/ha) Variety A Variety B Variety C Variety D Variety E kg N/ha

8 Traits for improving N use efficiency Improve efficiency of N uptake (kg N uptake / kg available N) Increase rate of N uptake Prolong duration of N uptake Increase N utilisation efficiency (kg seed yield / kg N uptake) Achieve same yield with less N Achieve greater yield with same N

9 N uptake efficiency Mean of 6 trials in 2006&7 February soil mineral N 50 February crop N 58 Optimum fertiliser N rate 166 N uptake at maturity 215 Soil and fertiliser N uptake efficiency 73% Net mineralisation/immobilisation after February not accounted for Data courtesy of Growhow Uk Ltd

10 Root length density Soil depth (cm) Root length density (cm/cm 3 ) mean Max Min Blake et al., 2006

11 Root length density 0 Root length density (cm/cm 3 ) Soil depth (cm) mean Max Min Blake et al., 2006 & BASF

12 Root length density 0-20 Root length density (cm/cm 3 ) Soil Mineral N (mean of 6 trials 2006&7) 0-30cm: 21 kg N/ha Soil depth (cm) mean Max Min 30-60cm: 15 kg N/ha 60-90cm: 14 kg N/ha Blake et al., 2006 & BASF

13 N uptake efficiency Average root length density (RLD) below 40 cm = 0.74 cm/cm 3 Increasing RLD to 1.0 cm/cm 3 is estimated to increase N recovered from soil by 8 kg N/ha (26%) Increase soil and fertiliser N uptake efficiency from 73% to 76%

14 Patterns of N uptake (2008) Measured without N fertiliser N uptake (kg/ha) Top 5 yielding varieties 100 Seed 90 Pod wall Flower 80 Stem 70 Leaf Mar-08 Apr-08 May-08 Jun-08 Jul-08 N uptake (kg/ha) Bottom 5 yielding varieties Seed Pod wall Flower Stem Leaf Mar-08 Apr-08 May-08 Jun-08 Jul-08

15 Patterns of N uptake (2007) Measured without N fertiliser Top 5 yielding varieties Bottom 5 yielding varieties 140 seed 140 seed 120 Flow er & pod w all stem 120 Flow er & pod w all stem 100 Leaf 100 Leaf N content (kg/ha) N content (kg/ha) Mar-07 Apr-07 May-07 Jun-07 Jul-07 0 Mar-07 Apr-07 May-07 Jun-07 Jul-07

16 Patterns of N uptake Measured without N fertiliser 4 experiments 5 highest yielding varieties ; yielded 0.55 t/ha more took up 22 kg N/ha more (all after flowering) 18% greater N uptake efficiency No difference in N utilisation efficiency between high and low yielding varieties

17 N utilisation efficiency (kg seed / kg N uptake)

18 Seed filling period is critical

19 Seed filling period is critical Optimum Green Area Index 3.5 Pods: 1.5 Stems: 1.0 Leaves: 1.0

20 Optimum N for photosynthesis 3 Leaf N Content (g m -2 ) PPFD (µmol m -2 s -1 ) Critchley, 2002

21 Optimum N for photosynthesis Split canopy into top half - (pods & upper stems) and bottom half (leaves and lower stems) Calculate the average light intensity in top and bottom half Estimate the specific tissue N based on light concentration Assume cylindrical surface area for stems & pods

22 Optimum N for photosynthesis at start of seed filling N content (kg/ha) Pod N Stem N Leaf N 0 Optimum for photosynthesis Typical crop

23 Patterns of N uptake & partitioning N content (kg N/ha) 250 Seed Pod & Flower 200 Stem Leaf Mar 28- Mar 11- Apr 25- Apr 9- May 23- May 6- Jun 20- Jun 4- Jul Mean of 3 experiments

24 Patterns of N uptake & partitioning N uptake (kg/ha) Seed Excess pod Pod & Flower Excess stem Stem Leaf Mar 28- Mar 11- Apr 25- Apr 9- May 23- May 6- Jun 20- Jun 4- Jul

25 Improving N utilisation efficiency Potential to either; reduce the N in stems & pod walls by 30 kg N/ha, or increase N remobilised from stems/pod walls to seed Varietal differences for N concentration and N content in stems and pods Stem N concentration at flowering: 1.02 to 1.32% (P<0.01) Stem N concentration at maturity: 0.55 to 0.68% (P<0.01) Stem N content at flowering: 46 to 63 kg N/ha (P<0.01) 2-fold difference between varieties for stem N remobilisation

26 Potential for improving N use efficiency Typical crop Yield (t/ha) 3.2 Total N uptake (kg/ha) 226 N already taken up by spring (kg/ha) 50 Soil & fertiliser N uptake efficiency 73% N available in soil (kg/ha) 50 Fertiliser N (kg/ha) 191 Fertiliser N use efficiency (kg seed dry matter/kg fertiliser N) 15.2

27 Potential for improving N use efficiency Typical crop Increase N utilisation efficiency Yield (t/ha) Total N uptake (kg/ha) N already taken up by spring (kg/ha) Soil & fertiliser N uptake efficiency 73% 73% N available in soil (kg/ha) Fertiliser N (kg/ha) Fertiliser N use efficiency (kg seed dry matter/kg fertiliser N)

28 Potential for improving N use efficiency Typical crop Increase N utilisation efficiency Increase N uptake efficiency Yield (t/ha) Total N uptake (kg/ha) N already taken up by spring (kg/ha) Soil & fertiliser N uptake efficiency 73% 73% 84% N available in soil (kg/ha) Fertiliser N (kg/ha) Fertiliser N use efficiency (kg seed dry matter/kg fertiliser N)

29 N use efficiency in oilseed rape Oilseed rape Wheat Rate of N fertiliser (kg N/ha) 191 (148) 184 Yield (t/ha) 3.2 (3.7) 8.0 Dry matter in seed (kg/kg N) 15.2 (22.8) 37.0 Energy in seed (MJ/kg N) 387 (581) 666 Energy in straw (MJ/kg N) 535 (690) 666 Total energy (MJ/kg N) 922 (1271) 1332

30 Conclusions Large potential for improving N use efficiency of oilseed rape Key traits Increasing N uptake efficiency by prolonging N uptake Increase N utilisation efficiency by reducing N stored in stems, or increasing remobilisation from stems Further work Confirm importance of key traits Identify genetic differences in key traits Measure genetic differences in economic optimum N

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