Evaluating Nutrient Uptake and Partitioning for Hybrid Carrot Seed Production in Central Oregon

E. Jeliazkova, A. Moore, J. Spring, T. Wilson
Oregon State University
ABSTRACT
​Hybrid carrot seed production is prominent in Central Oregon, however plant nutrient uptake dynamics in this crop are not well understood. The aim of this research was to evaluate nutrient uptake and partitioning during the production cycle of a modern Nantes-type hybrid carrot.  Trials were conducted in two commercial carrot seed production fields planted to ‘Nantes 969’. Below- and above-ground plant biomass was destructively sampled and separated into roots, tops, and umbels throughout the growing season, seed samples were collected at harvest. Biomass yield and nutrient content was evaluated throughout the growing season. All plant tissue was analyzed for total N, P, K, S, Ca, Mg, Na, Zn, Fe, Mn, Cu, and B concentrations. Mean whole plant nutrient uptake at crop maturity for N, P2O5, K2O, S, Ca, Mg, and Na was 123, 31, 204, 14, 94, 34, and 23 lb ac-1, respectively; Zn, Fe, Mn, Cu, and B uptake was 0.14, 1.77, 0.37, 0.03, and 0.27 lb ac-1, respectively. Our findings highlighted the importance of Cu in initial crop establishment, of N, K, Zn, and Fe in crown development, and of P and Zn in seed development, based on nutrient uptake amount relative to the other nutrients uptake during that period. This information is available as a resource to agronomists, crop advisors, and growers who are interested in optimizing nutrient management practices for hybrid carrot seed production.
INTRODUCTION
  • Central Oregon is an important region for hybrid carrot seed production
  • Seed yields of hybrid carrot varieties are lower and less consistent than open-pollinated varieties
  • Understanding how hybrid carrots use nutrients to support seed production
    • by matching timing of nutrient application with the period of greatest nutrient uptake
    • can help growers manage soil fertility for optimal seed yield
  • Evaluations of the nutrient uptake potential of carrot seed crop will provide an indication of how much of a specific nutrient the crop can take up
 
OBJECTIVE
The objective of this research was to evaluate in-season nutrient partitioning and uptake in root, tops, umbel, and seed, of Nantes-type hybrid carrot variety grown for seed on two grower fields in Central Oregon.
 
Carrot field in bloom, July 2018
Carrot field in bloom near Madras Oregon June 26, 2018. Photo credit to Ekaterina Jeliazkova, OSU. 
MATERIALS AND METHODS
Study sites
  • Two commercial production fields near Madras OR, Madras loam, (Aridic Argixeroll).
  • Similar soil properties and nutrient levels for both fields at 0-6 inches soil depth
    • Soil pH: 5.9 to 6.2
    • Soil organic matter: 1.9 to 2.0%
    • NO3-N: 114 to 187 ppm
    • Olsen (Sodium bicarbonate) P: 30 to 55 ppm
    • Olsen (Sodium bicarbonate) K: 228 to 239 ppm
  • Hybrid carrot variety ‘Nantes’ type 969 planted in mid-August 2017
  • Irrigated weekly May to August 2018
    • Field 1 – Furrow irrigated
    • Field 2 – Drip irrigated
Experimental design
  • Each field had 16 plots divided among four blocks established for a different study, with one plot per block selected at random for in-season nutrient uptake evaluations for this study
Birdseye view of furrow irrigated Field #1 (left) and drip irrigated Field #2 (right). Plant samples were collected from the green highlighted plots. Madras, Oregon. © 2018 Google LLC, used with permission.Birdseye view of furrow irrigated Field #1 (left) and drip irrigated Field #2 (right). Plant samples were collected from the green highlighted plots. Madras, Oregon. © 2018 Google LLC, used with permission.
  • Plot size varied slightly among plots based on field size and “dead patches”
    • Drip irrigated field
      • Plot length of 1158 to 1247ft;
      • Plot width of 12 female carrot rows
    • Furrow irrigated field
      • Plot length ranged from 1290 to 1590ft;
      • Plot width of 8 female carrot rows
Plant sampling and processing
  • Destructive sampling of whole female plants, roots included
    • Monthly, from October 2017 to August 2018
    • Winter months excluded due to minimal plant growth
  • Three randomly selected areas of 3 x 2.5ft per plot at each sampling event
  • Whole plant samples partitioned into roots, tops, and umbels with garden clippers
    • Fresh weights recorded, samples dried at 140° F, weighted, then ground
    • Subsamples instead of the whole composited sample partitioned during summer months
Partitioned subsample of carrot plant produced for seed. Tops (shoots), roots, and umbels (flowers) are located on the left, middle, and right portions of this photo, respectively. Photo credit to Amber Moore, OSU.
Partitioned subsample of carrot plant produced for seed. Tops (shoots), roots,
and umbels (flowers) are located on the left, middle, and right portions of this photo, respectively.
Photo credit to Amber Moore, OSU.
Seed sampling and processing
  • At harvest, 4 subsamples collected of harvested seed per plot, composited, and weighed
  • Cleaned on small scale lab equipment, weighed, dried, weighed, and ground
Plant nutrient analysis
  • All samples analyzed for:
    • Total N via combustion
    • P, K, S, Ca, Mg, Zn, Fe, Mn, Cu, and B via ICP-OES of nitric acid digests
RESULTS AND DISCUSSION: Dry matter accumulation and nutrient uptake
Total dry matter accumulation and nutrient uptake
  • Mean whole plant biomass (dry weight basis) was 7645 lb ac-1, ranged from 5,240 to 12,950 lb a-1 for individual plots (Table 1)
  • Approximately 7% in roots, 65% in tops, and 28% in umbels at crop maturity
  • Mean whole plant uptake of N, P2O5, K2O, S, Ca, Mg, and Na was 123, 31, 204, 14, 94, 34, and 23 lb ac-1, respectively
  • Mean whole plant uptake of Zn, Fe, Mn, Cu, and B was 0.14, 1.79, 0.37, 0.03, and 0.27 lb ac-1, respectively
  • Relative quantity of total umbel uptake at crop maturity (or nutrient removal) was: N > K2O > Ca > P2O5 > Mg > S > Na > Fe > Mn > B > Zn > Cu
  • Relative quantity of nutrient carryover in crop residue (roots and tops) was: K2O > N > Ca > Mg > Na > P2O5 > S > Fe > Mn > B > Zn > Cu
    • Potassium carryover was at an average of 150 lb ac-1 K2O
    • Nitrogen carryover was at an average of 63 lb ac-1 N
Seed yield and nutrient uptake
  • Seed biomass weight (dry weight basis) was only 3% of total aboveground biomass (tops + umbels)
  • Mean seed yield (dwb) was 222 lb ac-1 ranged from 151 to 324 lb ac-1 between individual plots over the two fields 
  • The highest mean seed nutrient uptake was: N (7 lb ac-1), Ca (6 lb ac-1), and K (4 lb ac-1K2O) (Table 2)
  • Mean seed nutrient concentration was 3.0, 0.5, and 1.6 % for N, P, and K, respectively
  • Approximately 8-9% of P and Zn were in the seed at harvest versus 1-7% for other nutrients
Table 2. Clean seed biomass accumulation and nutrient uptake for Nantes-type hybrid carrot in Madras, Oregon, averaged across two fields and four replications per field. Biomass values and seed nutrient uptake listed on a dry weight basis.
Whole plant nutrient uptake by season
In-season nutrient accumulation divided into three growth stages (Table 3).
Illustration of observed carrot plant growth at select sampling dates. Left photo: October 20, 2017. Middle photo: March 12, 2018. Right photo: June 26, 2018. Photo credits to Amber Moore and Ekaterina Jeliazkova, OSU.
Illustration of observed carrot plant growth at select sampling dates.
Left photo: October 20, 2017.
Middle photo: March 12, 2018.
Right photo: June 26, 2018.
Photo credits to Amber Moore and Ekaterina Jeliazkova, OSU.
 
During the stages plants accumulated:
      Initial establishment and winter/early spring dormancy (October to April)
  • Only 5% of total biomass
  • Only took up 3 to 7% of plant nutrients, with the notable exception of Cu where 15% of total uptake occurred during this period
    • Copper is critical for root development in plants
Mean biomass accumulation and nutrient uptake in Nantes-type hybrid carrot in Madras, Oregon over three growth stages.

     Vegetative stage (April to late May)

  • Approximately 11% of total biomass
  • Took up 10 to 23% of the total nutrients
    • Uptake of N, K, Zn, and Fe was the greatest, at 17-21% of total uptake
    • Versus only 11-16% of total P, S, Ca, Mg, Na, Mn, Cu, and B uptake
      Flowering and seed production (late May to August)
  • Approximately 84% of total biomass
  • Total nutrient uptake was 72 to 84%
  • Uptake of P, S, Mg, Ca, and B ranged from 80 to 84%
  • Peak nutrient uptake rate (lb nutrient-1 ac-1 day-1) was around 10 June for all nutrients except Fe, where peak uptake occurred on 13 July (Table 4)
Table 4. Maximum daily biomass accumulation and whole plant nutrient uptake rates in Nantes-type hybrid carrot type in Madras, Oregon.  Range represents the highest and the lowest value for individual plots during the period of maximum accumulation.
RESULTS AND DISCUSSION: Partitioned nutrient uptake by season
  • Patterns of K, Ca, and Mg uptake in root, tops, and umbels similar to in-season biomass accumulation patterns (Figures 1 and 2). 
Figure 1. In-season dry matter accumulations in Nantes-type hybrid carrot produced for seed in Madras, Oregon. Data collected from four replicated plots within two commercial carrot production fields on Madras silt loam over the 2017-2018 production cycle.
  • In contrast, in-season Na, Fe, and Cu uptake patterns differed dramatically from dry matter accumulation during specific growth periods (Figures 1 and 3).
    • During 23 Apr. 2018 to 26 June 2018, root uptake of Na and Fe increased 9.3-fold and 5.1-fold, respectively, compared to 20 Oct. 2017 to 23 Apr. 2018 period.
    • For all other nutrients, root uptake increased only by 2.5-fold to 3.5-fold.
    • Copper accumulations in the roots, tops, and umbels differed from other nutrients:
      • Total Cu uptake was 22% at the initial 20 Oct. 2017 sampling, with 77% of Cu concentrated in tops.
      • In comparison, only 3% of total biomass accumulated by that time. Although the reason for early season uptake of Cu for carrot seed production is not understood, this illustrates the importance of insuring adequate available Cu is present in the fall at carrot planting.    
 Figure 2. In-season N, P, K, S, Ca, and Mg uptake in Nantes-type hybrid carrot produced for seed in Madras, Oregon. Data collected from four replicated plots within two commercial carrot production fields on Madras silt loam over the 2017-2018 production cycle.
Figure 3. In-season Na, Zn, Fe, Mn, Cu, and B uptake in Nantes-type hybrid carrot produced for seed in Madras, Oregon. Data collected from four replicated plots within two commercial carrot production fields on Madras silt loam over the 2017-2018 production cycle.
CONCLUSION and ACKNOWLEDGEMENTS
Conclusion
These data may be used to inform and refine fertilizer rates and fertility practices in Nantes-type hybrid carrot seed production in Central Oregon, and in similar temperate irrigated production regions (Moore et al., 2020; DOI:10.1002/agj2.20503). 
 
Acknowledgements
We would like to thank John and Mike Weber with Central Oregon Seed Inc. for providing the support and guidance that was needed to conduct this study. We would also like to thank our cooperators, Richard Colman, Craig Weigand Jr., and Craig Weigand Sr. for providing the fields that allowed us to conduct these field trials.
Enduring angry bees while sampling carrot plant biomass in August, 2018
Enduring angry bees while sampling carrot plant biomass in August, 2018. Photo credit to Tracy Wilson.