R. Scott Veitch a, Rajasekaran R. Lada a, Azure Adams a & Mason T. MacDonald a a Department of Environmental Science, Dalhousie University,

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1 This article was downloaded by: [University of Florida] On: 21 April 2014, At: 05:07 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Communications in Soil Science and Plant Analysis Publication details, including instructions for authors and subscription information: Carrot Yield and Quality as Influenced by Nitrogen Application in Cut-and-Peel Carrots R. Scott Veitch a, Rajasekaran R. Lada a, Azure Adams a & Mason T. MacDonald a a Department of Environmental Science, Dalhousie University, Dalhousie Agricultural Campus, Bible Hill, Canada Accepted author version posted online: 18 Feb 2014.Published online: 01 Apr To cite this article: R. Scott Veitch, Rajasekaran R. Lada, Azure Adams & Mason T. MacDonald (2014) Carrot Yield and Quality as Influenced by Nitrogen Application in Cutand-Peel Carrots, Communications in Soil Science and Plant Analysis, 45:7, , DOI: / To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the Content ) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

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3 Communications in Soil Science and Plant Analysis, 45: , 2014 Copyright Taylor & Francis Group, LLC ISSN: print / online DOI: / Carrot Yield and Quality as Influenced by Nitrogen Application in Cut-and-Peel Carrots R. SCOTT VEITCH, RAJASEKARAN R. LADA, AZURE ADAMS, AND MASON T. MACDONALD Department of Environmental Science, Dalhousie University, Dalhousie Agricultural Campus, Bible Hill, Canada Root bulking, quality, and uniformity in cut-and-peel carrots (Daucus carota) are paramount for optimizing marketable yield and quality. Root bulking is an ecophysiological manifestation in response to inputs such as fertilizers. Understanding this ecophysioloical interaction will help to optimize yield, quality, and amount of inputs used. Three years of field trials were conducted in Kings County, Nova Scotia, to investigate the effects of varying levels of nitrogen (N) fertilizer on yield, recovery, and root and tissue N of two cut-and-peel varieties, Sugarsnax and TopCut. Seven levels of ammonium nitrate (34 0 0; 0, 50, 100, 150, 200, 300, and 400 kg N h 1 ) were hand broadcast in a split (60% pre-emergence and 40% 8 weeks after emergence) application. No significant interactive effects of N and variety in terms of gross yield or recovery were observed, though Sugarsnax total yields were 12.7% greater than those of TopCut. Overall, optimum yields were achieved at N rates of 150 kg N h 1 and further addition did not significantly improve yield or quality. Increased N significantly increased root and tissue N, but N concentration in both tissues peaked at the 300 kg N h 1 rate. However, neither root nor leaf tissue N had any effect on marketable or total yield. These results show that root bulking is not modulated by altering N applications, and the results also suggest that carrots may have high N-use efficiency or harness N from deeper zones. Keywords TopCut Ammonium nitrate, carrots, Daucus carota, root bulking, Sugarsnax, Introduction Processing carrots (Daucus carota L.) have become an important horticultural crop in the maritime provinces of Canada. Root quality and uniformity in cut-and-peel carrots is paramount for optimizing marketable yield and therefore profits (Pettipas et al. 2006). This can be achieved by understanding and controlling root bulking, which is an ecophysiological manifestation in response to management, environment, and inputs such as fertilizers. Understanding the ecophysioloical interactions between cultivar and nitrogen (N) will not only optimize yield and quality but also promote environmental stewardship and minimize input costs (Benjamin, McGarry, and Gray 1996). Utilizing inputs to maximize both yields and root quality has become more popular among producers, as producers Received 1 July 2012; accepted 17 March Address correspondence to Rajasekaran R. Lada or Mason T. MacDonald, Department of Environmental Science, Dalhousie University, Dalhousie Agricultural Campus, P.O. Box 550, Bible Hill, NS, B2N 5E3, Canada. raj.lada@dal.ca; Mason.MacDonald@dal.ca 887

4 888 R. S. Veitch et al. are moving toward better nutrient-management planning, decreasing their input costs, and focusing on sustainability (Pettipas et al. 2006). Nitrogen is one such input that is being reduced due to concerns over nitrate contamination in the soil, nitrate leaching into groundwater, and increasing cost of N fertilizers (Matsumoto, Ae, and Yamagata 2000; Pettipas et al. 2006, 2008). The use of N fertilizers is a common practice in carrot production, but previous studies on carrots show that increased rates of N do not necessarily enhance yields; optimum yields are usually obtained at around 150 kg N h 1 (Sanderson and Ivany 1997; Mubashir et al. 2010). Such a lack of response to applied N suggests that carrots are utilizing N from deeper (<30 cm) zones of the soil depending on the cropping history and other applied N sources such as manure (Pettipas et al. 2006). Cooler temperatures and rainfall could dramatically alter the availability, uptake, transport, and utilization of soil N, which makes it extremely difficult to maintain adequate N supply throughout the cropping season. Soil samples taken before seeding may not show accurate available N due to the moderate maritime climate (Pettipas et al. 2006). Another approach that has been discussed to assess N fertility in carrots is plant analysis (Pettipas et al. 2008). Several studies have evaluated and determined the nutrient content of both carrot leaves and roots (Sanderson and Ivany 1997; Warman and Havard 1997; Howard, McGillivray, and Yamaguchi 1962). However, these studies did not see if there was a relationship between N content and yield. More recent studies by Pettipas et al. (2006, 2008) examined critical tissues of dicer carrots for N concentration and their effects on yield. These studies found that analysis of the critical tissue was a better assessment tool for N status of a plant to predict yield. The objectives of our study were to investigate the effect of N on two cut-and-peel varieties (Sugarsnax and TopCut), determine the optimum level of N needed to maximize yield and quality, and determine whether N concentration of the roots and leaves may be used to predict yield responses. Materials and Methods Three one-site field trials were conducted in the Annapolis Valley located in Kings County, Nova Scotia, in 2007, 2008, and A randomized complete block design with three replications was used. Fields were seeded using a precision Stanhay-Webb Star 9 row seeder (Stanhay-Webb Ltd., Grantham, UK), and both varieties of cut-and-peel carrots were seeded at a rate of 33 seeds per 30 c 1. Rows were 0.6 m apart from the center with a plot size of 1.8 m by 10 m. Carrots were seeded 8, 13, and 14 May in 2007, 2008, and 2009, respectively. Fields received a base application of 350 kg h 1 of magnesium (Mg) 0.3 boron (B) before seeding for all 3 years. Chicken broiler manure was applied at 1.6 to 2.0 ton h 1 in the fall with the previous crop being a cereal grain. Treatment plots received increasing amounts of ammonium nitrate (34 0 0; 0, 50, 100, 150, 200, 300, and 400 kg N h 1 ). Split broadcast application was applied by hand at 60% pre-emergence and the remaining 40% was applied 8 weeks after emergence. Mature carrots were harvested as 1-m samples from each plot on 4, 9, and 15 September in 2007, 2008, and 2009, respectively. The numbers of roots per linear meter were recorded. Harvested carrots were then graded with a precision root grader into the following groups: undersized (<0.95 cm), baby or marketable (0.95 to 1.6 cm), fancy (1.6 to 2.5 cm), and oversized (>2.5 cm). Culls were those carrots that were split, rotted, green, forked, or disfigured. Baseline soil samples were taken before any fertilizer application was applied. Soil samples were also taken at midseason (July) and at final harvest. All soil samples were taken at a depth of 0 30 cm. Five soil cores were collected from each plot and mixed

5 Link between Nitrogen and Root Bulking 889 together to give a representative sample. Five carrot roots with tops intact were collected from each plot and used for the tissue samples for N analysis. Leaves were removed from roots and dried at 60 C, whereas roots were chopped up into smaller pieces and frozen for later analysis. Soil, leaf, and root total N were determined using a LECO model 528 CNS analyzer (LECO Corp., St. Joseph, Mich., USA). Weather data on various parameters (max/min ambient and soil temperature, rainfall, solar radiation, relative humidity, wind speed, and direction) for the entire growing season were also gathered using a weather station equipped with a data logger (Spectrum Technologies, Dallas, Tex., USA) installed at the site for each year. Data from the experiment were submitted to an analysis of variance (ANOVA) using Minitab 15 (Minitab Inc., University Park, Penn., USA). The statistical assumptions of normality, homogeneity, and independence were all satisfied. SAS was used for means separation for the experiment and was performed using Tukey s mean comparisons (α = 0.05). Regression analysis was completed in Minitab to determine relationships between yield and recovery. Results There was no significant interactive effect between N rates and cultivar for either baby grade or total yield. However, there were significant differences between cultivars as Sugarsnax yielded 17.6% more baby-grade carrots than TopCut, and had a 12.7% increase in total yield compared to TopCut (Table 1). Overall, yield was not significantly increased with increased N rates for marketable or total yield carrots. Only 2007 showed an effect by increasing N rates as marketable yields of 28.8 t h 1 and total yields of 42.5 t h 1 were achieved at 300 kg N h 1. However, it was noted that in all years yield was not significantly increased with applications of more than 150 kg N h 1 for total yield (Table 2). Yields at 300 and 400 kg N h 1 were less than expected, a result of reduced roots per meter. The number of roots per meter ranged from 53 to 82 for the 300 and 400 kg N h 1 treatment compared to the 82 to 103 roots per meter for all other N treatments. Fewer roots per meter may have been due to emerging young seedlings being burned off with the first split application of high amount of N. Cull carrots were also significantly affected by greater N rates as 9.1 t h 1 of culls were yielded at the 400 kg N h 1 rate. This was a significant 72% increase in culls compared to the 2.5 t h 1 atthe0kgnh 1 level and 3.7 t h 1 atthe50kg Table 1 Condensed ANOVA table indicating significance of main and interaction effects Source DF Marketable yield Total yield Year (Y) 2 P < P = Cultivar (C) 1 P < P < NRate(N) 6 P = P < Y C 2 P = 0356 P = Y N 12 P < P < C N 6 P = P = Y C N 12 P = P = Error 84

6 890 R. S. Veitch et al. Table 2 Effects of nitrogen for each year and combined years on marketable yield and total yield of cut-and-peel carrots, significant at α = 0.05 N Average Rate Marketable Total Marketable Total Marketable Total Marketable Total b 36.0 AB 30.2 a 40.4 A 16.5 c 26.1 B b 34.2 AB 28.2 a 37.6 A 17.6 c 31.1 AB b 37.7 A 30.2 a 40.7 A 18.0c 36.8 A b 40.1 A 31.9a 43.6A 17.9 c 37.8A b 39.2 A 29.9 a 41.4 A 15.2 cd 35.9 A a 42.5A 29.8 a 40.7 A 16.4 c 34.7 A b 34.6 AB 27.8 ab 40.0 A 12.2 d 35.1 A Notes. Letter groupings were determined using Tukey s multiple-means comparison. Bold numbers indicated the greatest yields. Lowercase letter groupings indicate differences in marketable yield response variable; capital case letter groupings indicate differences in total yield. Table 3 Soil nitrogen concentrations (%) for each year and combined years before seeding, at midharvest and at final harvest Average N rate Mid Final Mid Final Mid Final Mid Final Initial Nh 1 level (data not shown). The reason for not seeing a significant effect of increasing N rates on the yield could also be due to the high base fertility in this site (Table 3). Even though the field did receive 350 kg h 1 of Mg 0.3 B before seeding, the complete effects of previous crop and manure applications were not fully explored. This could be seen from the soil samples taken before seeding, midharvest, and final harvest. The percentage N at the mid- and final harvest showed very little variance from the initial soil test with increasing N rates (Table 3). Regression analysis showed that N rates had a highly significant relationship (R 2 = 0.98 for each) with percentage N concentration for both root and leaf tissue (Figures 1 and 2). It was also noted that the percentage N concentration began to level off between 200 to 300 kg N h 1 treatments for both root and leaf tissues. The relationships of root tissue N and leaf tissue N with total yield were significant, but the R 2 values were only 0.11 and 0.10, respectively (Figures 3 and 4), indicating that less than 11% of variability

7 Link between Nitrogen and Root Bulking 891 Figure 1. Effects of increasing rate of nitrogen on percentage of root tissue nitrogen in cut-and-peel carrots. Dots represent the average of 18 values at each treatment concentration and error bars represent standard error. Figure 2. Effects of increasing rates of nitrogen on percentage of leaf tissue nitrogen in cut-and-peel carrots. Dots represent the average of 18 values at each treatment concentration and error bars represent standard error. in total yield could be explained by leaf or root tissue N. These relationships were weak due to the variation among years as yields were affected by site and weather. Regression models done on weather data collected showed that degree-days, rainfall, maximum temperature, and minimum temperature had the greatest influence on carrot yields. These weather parameters had a significant effect on both Sugarsnax and TopCut marketable yields (Table 4). The relationship for both was strong as Sugarsnax and TopCut baby grades had R 2 values of 0.60 and 0.53, respectively. Total yields had much weaker relationships for both Sugarsnax and TopCut.

8 892 R. S. Veitch et al. Figure 3. Effects of percentage of root tissue nitrogen on total yield of cut-and-peel carrots, N = 126. Figure 4. Effects of percentage of tissue nitrogen on total yield of cut-and-peel carrots, N = 126. Discussion Nitrogen had little effect on the yields of cut-and-peel varieties Sugarsnax and TopCut. As reported in literature for other carrot products, the yields peaked at the 150 kg N h 1 rate (Hipp 1978; Sanderson and Ivany 1997; Rajasekaran, Adams, and Thiagarajan 2008; Gajewski et al. 2010; Mubashir et al. 2010). This is consistent with the recommended rate of N fertilizer for carrots, which ranges from 80 to 140 kg N h 1 (Smolen and Sady 2009). The 300 and 400 kg N h 1 treatments in this study actually lead to lower yields as seedlings in 2008 and 2009 were burned off with the first split application of N. In 2007, most of the applied N was dissolved into the ground, as the area received 87.6 mm of rain in the following 2 weeks after seeding. Compared to 2008 and 2009 in the same following 2 weeks after seeding, the area received 46.7 and 48.6 mm of rain, respectively. Similar problems occurred in irrigation experiments with slicer carrots as seedlings were being

9 Link between Nitrogen and Root Bulking 893 Table 4 Regression models of various weather parameters on the marketable and total yield of cut-and-peel varieties Sugarsnax and TopCut, and for combined varieties, significant at α = 0.05 Response P value R 2 Regression model Sugarsnax Baby yield baby = max min Total yield tyd = max min TopCut Baby yield baby = max min Total yield tyd = max min Combined Baby yield baby = max min Total yield tyd = max min burned off with the first split application of N in the nonirrigated plots (Rajasekaran and Adams 2007). Another factor that contributed to the lesser yields at the greater N rates were the amount of cull carrots. However, this was expected as more N would have increased bulking, causing cracking of root (Sanderson and Ivany 1997; Ali et al. 2003). It has been hypothesized that carrots are able to access N in the deeper layers of the soil. It has been shown that carrots can access N deeper than 30 cm. Those carrots are also able to take up organic forms of nutrients such as manures (Pettipas et al. 2008). There was a base coat of fertilizer of Mg 0.3 B applied at 350 kg h 1 before seeding, chicken broiler manure was applied in the fall at a rate of 4 to 5 ton a 1, and a previous crop of cereal grains was mainly used. The effects of the chicken manure and previous crop were not fully explored or taken in account as applied nutrients. Depending on soil conditions and weather, constant manure applications could allow nutrients that are not used to slowly migrate to the deeper layers of the soils and be inaccessible to those plants with shallow roots. However, because carrots are a taproot they may be able to access these nutrients that most shallow-rooted crops cannot use. Compared to other vegetables grown in the region, the Nova Scotia provincial recommendation to achieve optimal yields for carrots suggests lower levels of N. This therefore suggests that large amounts of fertilizers are needed to obtain desired yields (Pettipas et al. 2008). Even though N did not have an effect on the yields, it was noted that marketable yields were greater at the lesser N rates and that there were very little differences from the 0 to 150 kg N h 1 rates. The amount of roots per meter had more of an effect on marketable yields than N, suggesting that lesser amounts of N should be used with a greater seeding rate. Root and leaf tissue N increased with increasing rates of N, but the greatest N concentrations were achieved at 300 kg N h 1. However, these concentrations were not much greater than what was achieved at the 200 kg N h 1. In this study, the only significant correlation was between total yield and root N, but it had a very weak relationship as the R 2 was only Nitrogen is a very mobile nutrient and is taken up quickly depending on the growth stage of the plant. In carrots the rapid uptake of N generally occurs 2 months after emergence, which is at the active bulking stage (Mills and Jones 1996; Salo 1999; Pettipas et al. 2008). The lack of a relationship between root and tissue N, soil N content, and yields in the field has been shown in previous studies (Sanderson and Ivany 1997; Pettipas et al.

10 894 R. S. Veitch et al. 2006, 2008). It was suggested that the poor relationships between N and yield could be explained by how mobile N is in the soil. Current analytical methods do not provide a good predictive value. Conclusions The response to N application on yield was not significant, but greater rates of N did have an effect on the quality of carrots in Yields at the 150 kg N h 1 treatment were similar to yields achieved with 200, 300, and 400 kg N h 1, but for marketable yield carrots there were very little differences between the 0 and 150 kg N h 1 treatments. Nitrogen applications did have a significant correlation on root and leaf tissue N, as greatest concentrations were achieved between 200 and 300 kg N h 1. Root tissue N had a significant effect on total yield but was weakly correlated. Leaf tissue N had no significant effect on total and marketable yield of cut-and-peel carrots. The results from this study show that root bulking can be modulated by altering N applications. The results also suggest that carrots appear to be high in N-use efficiency. References Ali, A., M. A. Hossain, F. Mondal, and A. M. Farooque Effect of nitrogen and potassium on yield and quality of carrot. Pakistan Journal of Biological Sciences 6: Benjamin, L. R., A. McGarry, and D. Gray The root vegetables: Beet, carrot, parsnips and turnip. In The physiology of vegetable crops, ed. H. C. Wie. Wallingford, UK: CAB International. Gajewski, M., Z. Weglarz, A. Serdea, M. Bajer, A. Kuczkowska, and M. Majewski Carotenoid accumulation by carrot storage roots in relation to nitrogen fertilizer level. Notulae Botanicae Horti Agrobotanici Cluj-Napoca 38: Hipp, B. W Response by carrots to nitrogen and assessment of nitrogen status by plant analysis. Hortscience 13: Howard, F. D., J. H. McGillivray, and M. Yamaguchi Nutrient composition of fresh Californiagrown vegetables (Bulletin No. 788, California Agricultural Experiment Station). Berkeley: University of California. Matsumoto, S., N. Ae, and M. Yamagata Possible direct uptake of organic nitrogen from the soil by chingensai (Brassica campestris L.) and carrot (Daucus carota L.). Soil Biology and Biochemistry 32: Mills, H. A., and J. B. Jones Plant analysis handbook II. Athens, Ga.: MicroMacro. Mubashir, M., S. A. Malik, A. A. Khan, T. M. Ansari, S. Wright, M. V. Brown and K. R. Islam Growth, yield, and nitrate accumulation of irrigated carrot and okra in response to nitrogen fertilizer. Pakistan Journal of Botany 42: Pettipas, C. F., R. R. Lada, C. D. Caldwell, and C. Miller Leaf tissue testing and soil and plant tissue relationships for nitrogen management in carrots. Communications in Soil Science and Plant Analysis 37: Pettipas, C. F., R. R. Lada, C. D. Caldwell, and P. Warman Critical tissue identification and soil plant nutrient relationships in dicer carrots. Communications in Soil Science and Plant Analysis 29: Rajasekaran, L. R., and A. Adams The interactive effects of soil moisture and nitrogen fertilization on the yield and recovery of slicer carrots. Hortscience 42:879. Rajasekaran, L. R., A. Adams, and A. Thiagarajan Does nitrogen application alter ecophysiology, yield, and recovery of processing carrots? Hortscience 43:1197. Salo, T Effects of band placement and nitrogen rate on dry matter accumulation, yield, and nitrogen uptake of cabbage, carrot, and onion. Agriculture and Food Science 8 (2):

11 Link between Nitrogen and Root Bulking 895 Sanderson, K. R., and J. A. Ivany Carrot yield response to nitrogen rate. Journal of Production Agriculture 10: Smolen, S., and W. Sady The effect of various nitrogen fertilizers and foliar nutrition regimes on the concentration of sugars, carotenoids, and phenolic compounds in carrot (Daucus carota L.). Scientia Horticulturae 120: Warman, P. R., and K. A. Havard Yield, vitamin and mineral contents of organically and conventionally grown carrots and cabbage. Agriculture, Ecosystems and Environment 61: