Published September, 2009
Seed Yield and Yield Stability of Chickpea in Response to Cropping Systems and Soil Fertility in Northern Latitudes Y. T. Gan,* T. D. Warkentin, C. L. McDonald, R. P. Zentner, and A. Vandenberg
Improved cultural practices are required to enhance the adaptability of chickpea (Cicer arietinum L.) in northern latitudes. Field experiments were conducted to determine the effects of cropping systems, cultivar choices, and soil fertility on the stand establishment, seed yield, and yield stability of chickpea in northern latitudes. Four cultivars were tested in no-till barley (Hordeum vulgare L.), no-till wheat (Triticum aestivum L.), and tilled-fallow systems at six environments in southern Saskatchewan, 2004– 2006. Crop received N fertilizer at 0, 28, 64, 84, and 112 kg N ha–1 with or without Rhizobium inoculant (GR). The no-till barley and no-till wheat systems did not differ from the tilled-fallow system in days to plant emergence and stand establishment, and the two no-till systems averaged 2100 kg ha–1of seed yield which was 83% of the yield in the tilled-fallow system. In the absence of GR, increasing N rates increased seed yield significantly in the two no-till systems, no yield responses in the tilled-fallow system, and decreased plant density in all the three systems. Compared to the non-GR control, the use of GR increased seed yield by 37% in the no-till systems and 8% in the tilled-fallow system. Chickpea inoculated with GR produced a similar yield as was fertilized at 112 kg N ha–1. Chickpea receiving fertilizer N plus GR produced a similar yield as the crop received GR only for all cultivars. Use of optimal cropping systems, improved cultivars with high yield stability, and application of effective N-fi xing inoculants will enhance the adaptability of chickpea in northern latitudes.
C
hickpea is an annual grain legume traditionally grown in the tropics and the Mediterranean regions of the world (Siddique et al., 1998; Kumar and Abbo, 2001). In these areas, chickpea is considered a “cool-season” crop, and is sown in winter or spring depending on cropping systems. Since the 1980s, the production of this legume has extended to nontraditional areas, especially in northern latitudes, including the northern Great Plains of North America (Miller et al., 2002), northeast Eurasia, the Siberian steppes (Suleimenov, 2006), and northwest Europe (Knights et al., 2007). In these areas, chickpea is often referred as a “warm-season” crop (Gan et al., 2009b), largely because the entire lifecycle of this crop requires higher heat units and longer growing seasons than the dominant crop such as spring wheat. Climatic conditions in these higher latitude areas vary tremendously, including long and cold winters; short and warm summers; large and diurnal ranges in temperature; frequent strong winds; and highly variable and unpredictable precipitation (Padbury et al., 2002). The adaptation of the warm-season chickpea to the rather harsh environments is very challenging (Cutforth et al., 2007); there is a high risk that this crop Y. Gan, C.L. McDonald, and R.P. Zentner, Agric. and Agri-Food Canada, Airport Rd. E. Gate 3, Swift Current, SK, S9H 3X2, Canada; T.D. Warkentin and A. Vandenberg, Crop Development Centre, Univ. of Saskatchewan, Saskatoon, SK S7N 5A8, Canada. Received 28 Jan. 2009. *Corresponding author (
[email protected]). Published in Agron. J. 101:1113–1122 (2009). doi:10.2134/agronj2009.0039 Copyright © 2009 by the American Society of Agronomy, 677 South Segoe Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
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is unable to mature before the onset of a killing frost (–4°C) (Gan et al., 2009b). Chickpea has an indeterminate growth habit and consequently vegetative growth will continue for a prolonged period under cool, wet conditions, delaying pod setting and maturity. However, little information exists in the scientific literature regarding the effect of cultural practices on seed yield and yield stability of chickpea grown under northern latitude environments. Chickpea, along with lentil (Lens culinaris Medik.) and dry pea (Pisum sativum L.), has been used to replace conventional summerfallow in northern latitudes (Gan and Goddard, 2008). This practice provides significant environmental benefits in minimizing the risks of land erosion and soil degradation. Also, the inclusion of legumes in wheat-based cropping systems improves the water use efficiency (Miller et al., 2003) and grain yield of the subsequent wheat crop (Gan et al., 2003b), and enhances economic returns and sustainability (Zentner et al., 2002). In continuous no-till systems, chickpea can be grown after a wheat or barley crop, the two predominant cereals in northern latitudes (McKenzie et al., 2006). In a normal year, barley crop matures about 2 wk earlier and produces about 20% greater grain yield than spring wheat. However, little is known about whether the difference in maturity and productivity between the two cereals would affect chickpea the following year. Also, it is unclear whether the effect of previous crops on the following chickpea would interact with soil fertility in a broad range of environments. Being a legume, chickpea forms symbiotic associations with effective Rhizobium strains. Under favorable conditions, symbiotic N2 fi xation can produce >100 kg N ha–1 (Beck, 1992), Abbreviations: GDD, growing degree days; GR, Rhizobium inoculant in granular formulation; Tmax, daily maximum temperature; Tmin, daily minimum temperature.
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Pulse Crops
ABSTRACT
Table 1. Preseeding soil moisture and nutrients measured in the tilled-fallow, no-till barley, and no-till wheat systems, at Swift Current and Shaunavon, Saskatchewan, Canada, 2004–2006. Sys, soil depth, and nutrients cm Tilled-fallow 0–30 30–60 60–90 90–120 0–120 No-till barley 0–30 30–60 60–90 90–120 0–120 No-till wheat 0–30 30–60 60–90 90–120 0–120
Swift Current
Shaunavon
2004
2005
2006
3-yr mean 2004 Soil moisture, cm
2005
2006
3-yr mean
2.4 3.1 5.6 11.6 22.7
3.7 3.8 7.9 11.0 26.4
3.2 3.6 6.7 12.1 25.7
3.1 3.5 6.7 11.6 24.9
3.5 3.5 6.8 16.5 30.4
2.9 3.4 6.5 14.2 27.1
3.5 3.7 6.4 14.4 27.9
3.3 3.5 6.6 15.1 28.5
2.2 2.7 4.3 8.1 17.2
3.9 3.6 5.9 6.7 20.2
3.0 3.3 4.7 9.2 20.2
3.0 3.2 5.0 8.0 19.2
2.5 2.7 4.5 11.4 21.1
3.1 3.4 6.3 13.1 25.9
3.9 3.7 4.1 11.2 22.9
3.2 3.3 5.0 11.9 23.3
2.4 3.1 6.4 9.2 21.1
3.8 3.6 6.6 8.2 22.2
3.0 3.2 4.0 8.2 18.5
3.1 3.3 5.7 8.5 20.6
2.9 3.4 5.9 13.2 25.4
3.2 3.5 6.5 14.0 27.3
3.7 3.2 3.3 10.3 20.5
3.3 3.4 5.2 12.5 24.4
Soil nutrients, kg ha–1† Tilled fallow NO3–N P No-till barley NO3–N P No-till wheat NO3–N P
61
89
86
63
56
36
93
62
12
25
16
18
12
18
14
15
11
22
23
18
12
10
14
12
12
20
15
15
12
15
15
14
12 19
17 20
27 16
18 18
16 12
9 14
14 15
13 14
† NO3 –N was measured from 0 to 60 cm, and P from 0 to 15 cm soil depth.
and provide up to 85% of the N required by a chickpea crop (Rennie and Dubetz, 1986). However, nodule formation and N2 fi xation are influenced by environmental conditions (Paul, 1998; Kurdali et al., 2002) and cultural practices (Miller et al., 2002; Walley et al., 2005). In situations where N2 fi xation is limited by environmental stresses such as drought, the crop may benefit from fertilization since some synergistic effects can be derived from the combination of various N sources (Gan et al., 2008). However, little information exists regarding how this synergistic effect might be interacting with cropping systems. In conventionally tilled-fallow systems, the soil usually has a high level of residual N that may prohibit N2 fi xation activity (Clayton et al., 2004), while in continuous no-till cropping systems soil water is usually lower that may limit nodulation (Miller et al., 2003). Information on these subjects will be of critical importance in enhancing seed yield and yield stability of this crop in the cool, northern latitude areas. Therefore, the objective of this study was to determine the effects of cropping systems, cultivar choices, and application of N fertilizer and inoculation on the stand establishment, seed yield, and yield stability of chickpea in northern latitudes. MATERIALS AND METHODS Site Description and Experimental Design Field experiments were conducted at Swift Current (50°25´ N, 107°44´ W) and Shaunavon (49°37´ N, 108°25´ W), Saskatchewan, Canada, in 2004, 2005, and 2006. The soil at Swift Current was an Aridic Haploboroll with organic C content of 1114
20 g kg–1 and pH (CaCI2) of 6.8; the soil at Shaunavon was an Aridic Ustoll with organic C content of 18 g kg–1 and pH of 7.1. The six location-by-year combinations were considered six environments (the term “environment” was thereby used throughout the paper). Before seeding, a total of 48 cores (30-mm diam.) of soil samples were taken across the plot areas (12 cores in each of the four replicates). The soil samples were divided into the segments of 0–15, 15– 30, 30– 60, 60– 90, and 90– 120 cm. Each segment was split into two subsamples; one for the determination of soil water and the other for soil available nutrients. Soil moisture (% by wt) was converted to volumetric units using bulk densities of 1.11, 1.32, 1.39, 1.45, and 1.58 g cm–3, corresponding to the five soil depths. Soil NO3–N and bicarbonate extractable P were determined using the method described by Hamm et al. (1970). Soil available nutrient concentrations were calculated using the corresponding bulk densities described above (Table 1). The water held at field capacity is 340 mm and the water at permanent wilting is 135 mm to the 120-cm soil depth. At each environment, the following four chickpea cultivars were tested: ‘CDC-Xena’, a large kabuli chickpea with seed size of 465 mg seed–1; ‘CDC-Frontier’, a medium size kabuli chickpea with seed size of 365 mg seed–1; ‘Amit’, a small kabuli with 260 mg seed–1; and ‘CDC-Anna’, a desi type with 210 mg seed–1. Kabuli and desi types are two market classes of chickpea differing in the color of their flowers and seed coats. Kabuli plants have white flowers and creamy seed coat, whereas desi plants have pink flowers and dark brown seed coat. The Agronomy Journal
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Ascochyta rabiei (Pass.) Labrousse, was detected on the crop during the mid- to late-seedling stage each year. Thus, two to four applications of chlorothalonil (Syngenta Crop Protection Canada, Inc., Calgary, AB) and pyraclostrobin (Bayer Crop Science, Research Triangle Park, NC) were used at labeled rates to minimize disease damage. Plant counts were conducted at two spots (0.5 m2 each) in each plot 3 wk after emergence. At maturity, two 1-m2 samples were hand harvested in each plot for the determination of biomass, yield components, and harvest index. When seed moisture reached about 160 g kg–1, the central six rows in each plot were harvested using a plot combine, and seed yield determined. Daily minimum (Tmin) and maximum temperatures (Tmax), and rainfall during the growing season (May-August) were obtained from a meteorological station located within 400 m of the research plots. Growing degree-days (GDD) accumulated during the periods from planting to seedling emergence were determined for each treatment. The calculation was on a base temperature of 5°C (Gan et al., 2009b).
cultivars used in the experiment were chosen based on their production popularity. In general, these cultivars have a similar growth pattern (Vandenberg et al., 2003; Warkentin et al., 2005), but they mature differently (Gan et al., 2009b). In a normal year, CDC-Frontier matures 4 to 5 d later than Amit and CDC-Xena, and 3 to 4 d later than CDC-Anna. We used multiple cultivars in this study, aiming at determining the importance of choice of cultivars relative to other factors such as cropping systems, soil fertility, and environments in affecting the adaptability of the crop. All cultivars were tested in three cropping systems: (i) no-till barley system, (ii) no-till wheat system, and (iii) conventionally tilled summerfallow system, each being under the following fertility/inoculation conditions: 1. N = 0, no-inoculant (control); 2. N = 0, with Rhizobium inoculant (GR); 3. N = 28 kg ha–1, no-inoc.; 4. N = 56 kg ha–1, no-inoc.; 5. N = 84 kg ha–1, no-inoc.; 6. N = 112 kg ha–1, no-inoc.; 7. N = 28 kg ha–1 with GR;
Statistical Analysis The data were analyzed using the PROC MIXED procedure of SAS (Littell et al., 1996) with applied treatments as fi xed effects, and environments and replicates as random effects. A combination of variance estimates and P values were used to determine the relative importance of the effects due to environments and the applied cultural practices. Fisher’s protected LSD values were determined using LSMEANS with the PDIFF option of the MIXED model. Effects were declared significant at P < 0.05. Due to significant environment × treatment interactions for seed yield, an extension of the MIXED model was implemented to further categorize the interactions into different classes where environments were considered as a covariable cross-classified with the fi xed factors (Littell et al., 2002). First, an inference range was defined, that is, the overall environment means of seed yields across all treatments ranging from the minimum to the maximum environmental means. Then, the covariance ANOVA was applied to the inference range to estimate treatment effects at the minimum, average, and maximum environmental means. Finally, the covariance analysis categorized the treatment × environment interaction into the three classes, that is, the environments under which seed yield had a low-, average-, or high-response to the applied
8. N = 84 kg ha–1 with GR. Plots with Rhizobium inoculant (GR) as part of the experimental design received 5.5 kg ha–1 of ‘Nitragin GC’ in a granular form (LiphaTech Inc., Milwaukee, WI), applied with the seeds. The inoculant contained a minimum of 100 million viable cells of Mesorhizobium cicer per gram. Plots with fertilizer N as part of the experimental design received N as urea (46–0–0) fertilizer side-banded 6.0 cm deep. All plots received a blanket application of triple superphosphate (0–45–0) fertilizer to supply P at 20 kg P ha–1. The N levels and inoculation were not a full factorial due to the consideration of the size of the experiment. The three factors (cropping system, cultivar, and soil fertility) were arranged in a split-plot design with four replicates. Cropping systems were main plots and cultivar by fertility/inoculation combinations were subplots (2 by 10 m). At each environment, there were 384 experimental units (three cropping systems × four cultivars × eight fertilities × four replicates). Seeding, Plot Management, and Data Collection Plots were seeded between 6 and 18 May when noon soil temperature at 100-mm depth was between 9 and 14°C (Table 2). Seeding rates were calculated on the base of seed germination, seed size, and estimated field emergence rate, targeting a plant density of 45 plants m–2 . Seed was pretreated with carbathiin, thiabendazole, and metalaxyl at labeled rates to manage soil- and seed-borne diseases. Seed was planted 40 mm deep with 0.254 m between seed rows using a hoe press drill equipped with side-band openers, fertilizer box, inoculant box, and a seed divider. Conventionally tilled fallow plots were prepared using one pass of preseeding harrowing, while the no-till plots were directly planted into standing (about 0.2 m in height) cereal stubble. Weed control was achieved using a previous fall broadcast of ethalfluralin, a preseeding treatment with glyphosate, and in-crop application of sethoxydim, all at labeled rates. Ascochyta blight, a foliar disease caused by Agronomy Journal
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Table 2. Seeding and harvest dates for chickpea crop grown at Swift Current and Shaunavon, Saskatchewan, 2004–2006. Year and location 2004 Swift Current Shaunavon 2005 Swift Current Shaunavon 2006 Swift Current Shaunavon
2009
Seeding date
Soil temperature at seeding °C
Harvest date
7 May 18 May
14 14
28 Sept.–7 Oct. 8 Oct.–15 Oct.
10 May 13 May
10 9
2 Sept.–19 Sept. 8 Sept.–28 Sept.
6 May 10 May
13 11
17 Aug.–22 Aug. 16 Aug.
1115
Fig. 2. The relationship between plant density and the rates of N fertilizer for chickpea cultivars grown in southern Saskatchewan, 2004–2006; the data were averages across treatments and site-years.
the rate of N fertilizer for each cropping system, and between plant density and N rates for each cultivar.
Fig. 1. Daily maximum and minimum temperatures and rainfall during the growing seasons of 2004, 2005, and 2006 in southern Saskatchewan compared with long-term (1960– 2005) averages. The numbers in parenthesis are accumulated total rainfall during the growing season. The vertical arrows indicate the time of first flowering in chickpea averaged across all treatments. Weather patterns were essentially similar between Swift Current and Shaunavon in each of the 3 yr, and thus the weather data were averaged across the two locations.
treatments. This analysis helped determine the range of treatment responses to the diverse environments within the defined inference range. Also, ANOVA revealed that there was a highly significant interaction among environment, cultivar, cropping systems, and soil fertility. To further categorize these responses for a given treatment (i.e., cultivar) or treatment combination (i.e., cultivar × N rate combination), a grouping methodology, as described initially by Francis and Kannenberg (1978), further detailed by Yan and Tinker (2006), was employed to further explore random variability or stability associated with specific environments. Means and coefficients of variation (CV) for each cultivar by N rate combination were estimated across the various levels of yields and N rates. The yield variable was plotted against its corresponding CV, producing a biplot. The biplot, together with the scatter of data points, was used to describe four response categories: Group I: High yield, low variability (optimal); Group II: High yield, high variability; Group III: Low yield, high variability (poor); and Group IV: Low yield, low variability. These biplots gave an indication of the relative stability of chickpea seed yield in response to applied cultural practices. Linear regression was used to describe the relationship between seed yield (and biomass) and 1116
RESULTS Weather Conditions and Plant Establishment The amounts and distribution of growing season rainfall varied considerably among the three study years (Fig. 1). Accumulated growing season rainfall in 2004 (272 mm) was ≈34% above the long-term (1950–2005) average, near normal in 2005, and was 12% below average in 2006. Mean daily temperature during the growth season also varied during the course of the study; it was greater in 2006 (14.8°C) than that in 2004 (12.5°C) and 2005 (13.1°C), with both Tmax and Tmin during the grain fi lling period was noticeably higher in 2006. Seedling emergence occurred 23, 16, and 12 d after planting in 2004, 2005, and 2006, respectively (Table 3). Rapid seedling emergence in 2006 was due to high temperatures, especially Tmin immediately after planting (Fig. 1). On average, the growing degree days (GDD) required for seedlings to emerge was about 207 units, and the GDD requirements did not differ between cultivars or between years, even though GDD values at Swift Current in 2005 were relatively lower than those at the other environments (Table 3). No difference in GDD requirements for seedling emergence was observed between no-till and tilled-fallow systems at any of the six environments. Overall, plant establishment was adequate at all six environments, ranging from 36 to 47 plants m–2 , within the optimal range of plant density recommended for the production of chickpea in the northern Great Plains (Gan et al., 2003a). Plant density did not differ among cropping systems, nor did it among cultivars tested. However, there was a negative linear association between rates of N fertilizer and plant density (Fig. 2). Increasing N rates decreased plant density for all cultivars, while the cultivar CDC-Xena had the highest plant count at a given rate of fertilizer N. Crop Yields and Yield-Related Variables Analysis of variance revealed significant effects of cultivar, soil fertility, and cropping system × soil fertility interactions for biomass and seed yield (Table 4). The effect of applied Agronomy Journal
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Table 3. Days to seedling emergence (DAP, d) and growing degree days (GDD, 5°C basis) for chickpea cultivars grown in tilledfallow, no-till barley and no-till wheat systems (Sys), at Swift Current and Shaunavon, Saskatchewan, Canada, 2004–2006. Swift Current 2004 Sys and cultivar Cropping system Tilled fallow No-till barley No-till wheat Cultivar Amit CDC-Anna CDC-Frontier CDC-Xena
Shaunavon
2005
2006
2004
2005
2006
DAP
GDD
DAP
GDD
DAP
GDD
DAP
GDD
DAP
GDD
DAP
GDD
26 25 24
224 209 199
16 16 16
173 173 173
12 13 13
182 201 201
17 17 17
199 199 199
16 16 16
236 236 236
11 11 11
228 228 228
25 26 25 25
209 224 209 209
15 17 15 17
163 173 163 173
13 13 13 13
201 201 201 201
17 18 17 17
199 218 199 199
15 15 16 16
227 227 236 236
11 11 11 11
228 228 228 228
Table 4. Summary of ANOVA results for biomass, seed yield, and harvest index for chickpea treatments on biomass followed a cultivars affected by cropping systems, soil fertility, and environments, in Saskatchewan, similar trend as the effect on seed Canada, 2004–2006. yield, thus we discuss seed yield Seed effects in detail. Cropping systems Total % green Harvest had a significant interaction with Effects biomass Yield weight seed index environments in affecting seed Fixed factors P values yield. Using environments as a Cropping system (Sys) 0.081 0.686 0.388 0.378 0.346 covariable across-classified with Cultivar
