1. Introduction
Fe is a key micronutrient for most living organisms to conduct ubiquitous metabolic processes involving electron transfer. Examples of such metabolic processes include DNA synthesis, oxygen transport, cellular respiration, and photosynthesis. Moreover, Fe is vital as a co-factor in numerous heme-complexes, for example, hemoglobin, catalase and DNA helicases [
1,
2,
3]. Although Fe in many arable lands is relatively abundant (range concentrations of 20-40 g kg
-1), the low amount of the available form has resulted in Fe deficiency that limits plant growth [
4]. Since Fe is highly reactive to oxygen, formation of insoluble oxidized Fe (III) restricts Fe uptake by roots especially in high pH and high HCO
3- calcareous soils. In high pH and well aerated soils, the total conc. of Fe in soil solution was around 10
-10 M, which is 10
-4 - 10
-5 folds less than the required amount for optimum plant growth [
5,
6]. In terms of Fe uptake from soil, plants are divided into two categories: Strategy I in nongraminaceous plants and Strategy II in graminaceous plants [
6]. Strategy I plant species acquires Fe after the reduction of Fe (III) chelates at the root surface followed by absorption of Fe (II) ions throughout the plasma membrane [
7]. Since one-third of the world’s arable land is too alkaline for optimum plants growth, many studies have focused on how plants acclimatized with Fe deficiency [
8]. In addition, limited uptake of Fe was mostly observed in Strategy I plant species that depend on ferric reductase for transferring Fe [
9,
3]. Consequently, this condition decreased plant productivity and led to low quality including low Fe content in seeds that ultimately result in public health problem. Fe in plant-based diets is a non-heme Fe that is less bioavailable than heme Fe. As such, the prevalence of Fe deficiency induced anemia often occurred in populations where total calorie intake came from monotonous plant-based diets [
1].
Biofortification is a long-term food-based approach to alleviate micronutrient deficiency. It is a strategy of producing staple food crops with increasing concentration of bioavailable micronutrients in the edible parts, that is considered more sustainable and economical [
10,
11]. To increase bioavailable Fe in seeds, Fe biofortification strategy can be implemented that includes agronomy, plant breeding and genetic engineering approaches [
12]. Agronomic approach could be a rapid solution to boost Fe content in plants. Furthermore, agronomic biofortification can be integrated with other breeding-based biofortification methods [
13]. Agronomic biofortification, which is also known as ferti-fortification, involves the use of fertilizer either to soil and/or to foliage to increase the bioavailability of nutrients in edible parts of plant [
14,
15]. Adding micronutrients in soil is a functional strategy to enhance nutritional status in plant [
16,
17,
18]. However, there are several factors that control the increase of bioavailable nutrient into seeds. For example, source of fertilizer, time and application method of fertilizer, and quantity of fertilizer [
19,
20]. As Fe can be rapidly converted into unavailable form when it is applied to high pH soil, the application of inorganic fertilizer such as ferrous sulphate (FeSO
4) could be ineffective [
3]. Synthetic Fe chelates, in which Fe is combined with an organic chemical to form a chelate makes the Fe in a form accessible to plants. Moreover, Fe-chelates is soluble for a longer period than inorganic Fe. In this context, the application of chelated Fe fertilizers, for example, Fe-DTPA, Fe-EDTA and Fe-EDDHA can be effective in high pH soils. Among the three, Fe-EDDHA is the most effective Fe fertilizer than others [
21].
Chickpea (
Cicer arietinum L.) is a staple food crop in many African and Asian countries where the incidence of Fe deficiency is common [
1,
22,
23] . Based on global production, chickpea is the second most important pulse after common bean [
24]. Globally, chickpea production has increased gradually mostly (96%) in developing countries [
24]. Like production, the highest chickpea consumption rate occurred in the South Asia and Middle East-North Africa at 4.25 kg person
-1 and 2.11 kg person
-1 year
-1, respectively [
25]. The growth of chickpea consumption has also increased in developed countries. In USA, the consumption of chickpea has increased almost double from 199.6 g in 2010 to 322.1 g per person per year in 2014 [
26]. Chickpea is consumed in a variety of ways, for example, green pods, immature seeds and young leaves as vegetables, whereas as the primary commodity, chickpea is consumed as dried mature seeds, as whole, hulled or flour form [
27,
28]. Nutritionally chickpea is a rich source of protein (20-22%) along with micronutrients including Fe (3.0-14.3 mg 100 g
-1) [
29,
30]. Therefore, Fe biofortification of chickpea to produce seeds with increased Fe concentration can mitigate Fe deficiency in populations with poor Fe intake [
22]. Several studies have reported that agronomic approach could result in higher micronutrients in edible parts of different crops. Examples of successful agronomic biofortification include zinc (Zn) fertilizer to wheat and selenium (Se) to maize [
31,
32]. Moreover, in chickpea, soil application of Zn fertilizer increased grain Zn content and Zn yield compared to control [
33]. In addition, foliar application of Zn and Fe fertilizer also increased grain Zn yield in chickpea and leaves, stems and grains Fe content in mung bean [
33,
34]. Foliar application of Se fertilizer increased Se concentration in pea and common bean seeds [
35,
36]. In addition, Fe and Zn concentration in grain of cowpea increased after applying Zn-EDTA in potting compost [
37]. Combined application of Zn-DTPA and ZnSO
4 also increased Fe and Zn content in bean using hydroponic system [
38]. Fe biofortification in cowpea also showed that combined application of ferrous sulfate and ferrous chelate in potting compost increased Fe content of cowpea seeds compared to control [
39]. In terms of bioavailability, several authors reported that Zn and Se fertilization increased their bioavailability in human diets [
40,
41,
42].
To date, there is no report on the agronomic approach for Fe biofortification in chickpea. Given the importance of soil-Fe concentration, soil pH and HCO3- level, we hypothesised that the application of Fe fertilizer through soil increased Fe concentration in seeds. The main objectives of this study were: 1) to evaluate the effects of soil applied Fe fertilizer on Fe concentration in the seeds; and 2) to find out correlation between the Fe concentration and yield and correlation between the Fe concentration and Fe yield.
3. Results
The effects of soil-applied Fe fertilizer across locations, years, their interaction (location*year), cultivar, dose and their interaction (cultivar* dose) along with all the two, three, and four-ways interactions on different parameters of chickpea cultivars are presented in
Table 5.
Table 5.
Analysis of variance and F values of the effect of location (LOC), year (YEAR), replication (REP), cultivar (CUL), dose (DOS) and the interaction of LOC*YEAR, LOC*CUL, LOC*DOS, CUL*YEAR, CUL*DOS, DOS*YEAR, LOC*YEAR*CUL, LOC*YEAR*DOS, CUL*YEAR*DOS, CUL*LOC*DOS, and LOC*YEAR*CUL*DOS on germination (%), node no., days to flowering (50%), days to maturity (50%), plant height (cm), biomass (g), 1000 seed weight (g), yield (kg ha-1), seed Fe (µg g-1) and Fe yield (g ha-1) of eighteen chickpea cultivars with three doses of Fe-EDDHA over four replications at both sites.
Table 5.
Analysis of variance and F values of the effect of location (LOC), year (YEAR), replication (REP), cultivar (CUL), dose (DOS) and the interaction of LOC*YEAR, LOC*CUL, LOC*DOS, CUL*YEAR, CUL*DOS, DOS*YEAR, LOC*YEAR*CUL, LOC*YEAR*DOS, CUL*YEAR*DOS, CUL*LOC*DOS, and LOC*YEAR*CUL*DOS on germination (%), node no., days to flowering (50%), days to maturity (50%), plant height (cm), biomass (g), 1000 seed weight (g), yield (kg ha-1), seed Fe (µg g-1) and Fe yield (g ha-1) of eighteen chickpea cultivars with three doses of Fe-EDDHA over four replications at both sites.
Sources of Variation |
df |
Germination |
Node Number |
Days to Flowering |
Days to Maturity |
Plant Height |
Biomass |
1000 Seed Weight |
Yield |
Seed Fe Conc |
LOC |
1 |
68.3**
|
3.6ns
|
1232**
|
536**
|
766**
|
101**
|
0.6ns
|
1254**
|
1248**
|
YEAR |
1 |
227**
|
93.8**
|
131**
|
12804**
|
5701**
|
0.8ns
|
1385**
|
1367**
|
884**
|
REP |
3 |
0.9ns
|
3.0*
|
3.2*
|
1.9ns
|
4.7*
|
2.4*
|
7.8**
|
22.0**
|
12.4**
|
CUL |
17 |
4.3**
|
9.9**
|
12.2**
|
8.2**
|
17.5**
|
8.1**
|
116**
|
35.1**
|
19.3**
|
DOS |
2 |
1.3ns
|
0.7ns
|
1.8ns
|
2.7ns
|
0.3ns
|
61.7**
|
1.7ns
|
0.0ns
|
14.1**
|
LOC*YEAR |
1 |
0.9ns
|
19.0**
|
395**
|
968**
|
157**
|
1292**
|
99.0**
|
1866**
|
88.9**
|
LOC*CUL |
17 |
1.4ns
|
1.4ns
|
2.1*
|
2.4*
|
1.9*
|
6.0**
|
3.1**
|
5.9**
|
2.5*
|
LOC*DOS |
2 |
1.6ns
|
1.4ns
|
4.3*
|
15.8**
|
2.0ns
|
25.5**
|
3.4*
|
3.6*
|
0.9ns
|
CUL*YEAR |
17 |
6.9**
|
3.5**
|
6.8**
|
6.1**
|
3.2**
|
9.4**
|
17.0**
|
7.7**
|
11.0**
|
CUL*DOS |
34 |
1.2ns
|
1.2ns
|
0.6ns
|
0.7ns
|
0.5ns
|
1.4ns
|
0.7ns
|
1.6*
|
0.6ns
|
DOS*YEAR |
2 |
2.5ns
|
0.2ns
|
1.4ns
|
1.5ns
|
2.6ns
|
2.4ns
|
2.0ns
|
1.3ns
|
4.1*
|
LOC*YEAR*CUL |
17 |
1.5ns
|
3.1**
|
6.0**
|
2.4*
|
2.6*
|
3.2**
|
4.2**
|
12.6**
|
2.0*
|
LOC*YEAR*DOS |
2 |
2.0ns
|
0.4ns
|
0.5ns
|
11.3**
|
0.6ns
|
32.1**
|
1.5ns
|
1.3ns
|
1.4ns
|
CUL*YEAR*DOS |
34 |
1.1ns
|
1.6*
|
0.7ns
|
0.8ns
|
0.7ns
|
1.0ns
|
0.8ns
|
2.4**
|
0.7ns
|
CUL*LOC*DOS |
34 |
0.9ns
|
0.8ns
|
0.6ns
|
0.7ns
|
0.7ns
|
1.1ns
|
0.8ns
|
1.7*
|
0.9ns
|
LOC*YEAR*CUL*DOS |
34 |
1.1ns
|
1.3ns
|
0.9ns
|
0.8ns
|
0.5ns
|
1.9*
|
0.8ns
|
1.5*
|
1.2ns
|
Across the sixteen different factors, cultivar (CUL) and the interaction of cultivar and location (CUL*LOC) were highly significant (
p < 0.01) for all parameters. Furthermore, the effect of location (LOC), year (YEAR), replication (REP), the interactions of location and year (LOC*YEAR), location and cultivar (LOC*CUL), and location, year and cultivar (LOC*YEAR*CUL) were also significant on most of the parameters. However, the effects of Fe fertilizer were significant only on plant biomass and seed Fe concentration. The interaction effects between cultivar and fertilizer dose (CUL*DOS), dose and year (DOS*YEAR), location, year, and dose (LOC*YEAR*DOS), cultivar, year, and dose (CUL*YEAR*DOS), cultivar, location, and dose (CUL*LOC*DOS) and location, year, cultivar, and dose (LOC*YEAR*CUL*DOS) on most of the parameters were not significant. However, the interaction effects of location and dose (LOC*DOS) were significant on most of the parameters, except germination, node number, plant height, and seed Fe concentration (
Table 5).
The effects of soil-applied Fe fertilizer across locations, cultivar, dose and their interaction(location*cultivar), (location*dose), (cultivar*dose), and (location*cultivar*dose) on disease ascochyta blight score of chickpea cultivars in 2016 are presented in
Table 6.
Table 6.
Analysis of variance and F values of the effect of location (LOC), replication (REP), cultivar (CUL), dose (DOS) and the interaction of LOC*CUL, LOC*DOS, CUL*DOS, and CUL*LOC*DOS on disease score of eighteen chickpea cultivars with three doses of Fe-EDDHA over four replications at both sites in 2016.
Table 6.
Analysis of variance and F values of the effect of location (LOC), replication (REP), cultivar (CUL), dose (DOS) and the interaction of LOC*CUL, LOC*DOS, CUL*DOS, and CUL*LOC*DOS on disease score of eighteen chickpea cultivars with three doses of Fe-EDDHA over four replications at both sites in 2016.
Sources of Variation |
df |
Disease score |
LOC |
1 |
62.4**
|
REP |
3 |
37.7**
|
CUL |
17 |
8.9**
|
DOS |
2 |
2.1ns
|
LOC*CUL |
17 |
0.6ns
|
LOC*DOS |
2 |
13.2**
|
CUL*DOS |
34 |
0.5ns
|
LOC*CUL*DOS |
34 |
0.7ns
|
Across the eight different factors, location (LOC), cultivar (CUL), replication (REP) and the interaction of location and dose (LOC*DOS) were highly significant (
p < 0.01) for ascochyta blight disease score. However, the effect of Fe fertilizer on the disease severity was not significant. The interaction effects between location and cultivar (LOC*CUL), cultivar and dose (CUL*DOS) and cultivar, location, and dose (CUL*LOC*DOS) on disease were also not significant (
Table 6).
3.1. Biomass
The biomass data were based on the mean dry weight of randomly harvested five plants per plot. The mean biomass (g) of each of eighteen chickpea cultivars with three Fe fertilizer doses (0 kg ha
-1, 10 kg ha
-1, and 30 kg ha
-1) at both locations in 2015 and 2016 are presented in
Table 7.
Table 7.
The mean biomass (g plant-1) of eighteen chickpea cultivars with three Fe fertilizer doses (0 kg ha-1, 10 kg ha-1, and 30 kg ha-1) at Elrose and Moose Jaw in 2015 and 2016.
Table 7.
The mean biomass (g plant-1) of eighteen chickpea cultivars with three Fe fertilizer doses (0 kg ha-1, 10 kg ha-1, and 30 kg ha-1) at Elrose and Moose Jaw in 2015 and 2016.
Cultivars |
Elrose |
Moose Jaw |
|
2015 |
2016 |
2015 |
2016 |
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
Cultivars Mean |
1173-1 |
199 |
208 |
255 |
109 |
119 |
127 |
89 |
125 |
99 |
157 |
166 |
182 |
153 |
1460-2 |
175 |
232 |
244 |
112 |
116 |
124 |
118 |
89 |
105 |
171 |
257 |
171 |
159 |
AB06-156-2 |
149 |
280 |
295 |
101 |
117 |
146 |
149 |
127 |
157 |
198 |
201 |
207 |
177 |
Amit |
195 |
220 |
244 |
126 |
136 |
160 |
118 |
125 |
148 |
216 |
246 |
247 |
182 |
CA05-75-45 |
179 |
198 |
263 |
125 |
128 |
149 |
87 |
108 |
139 |
173 |
189 |
263 |
167 |
CDC Alma |
183 |
170 |
208 |
82 |
92 |
100 |
102 |
119 |
85 |
162 |
121 |
113 |
128 |
CDC Cabri |
166 |
260 |
329 |
129 |
144 |
161 |
81 |
73 |
111 |
127 |
178 |
153 |
159 |
CDC Consul |
116 |
215 |
223 |
133 |
139 |
143 |
83 |
125 |
85 |
176 |
207 |
261 |
159 |
CDC Corinne |
167 |
226 |
260 |
147 |
148 |
170 |
129 |
138 |
134 |
196 |
217 |
219 |
179 |
CDC Cory |
167 |
250 |
262 |
160 |
162 |
174 |
109 |
143 |
123 |
229 |
245 |
301 |
194 |
CDC Frontier |
238 |
240 |
263 |
136 |
161 |
169 |
136 |
137 |
121 |
243 |
264 |
248 |
196 |
CDC Leader |
195 |
222 |
235 |
137 |
141 |
145 |
94 |
82 |
86 |
205 |
216 |
259 |
168 |
CDC Luna |
150 |
248 |
304 |
115 |
134 |
130 |
102 |
90 |
93 |
100 |
164 |
165 |
150 |
CDC Orion |
207 |
316 |
389 |
130 |
134 |
148 |
105 |
109 |
106 |
191 |
191 |
197 |
185 |
CDC Palmer |
166 |
170 |
215 |
119 |
132 |
141 |
113 |
112 |
95 |
222 |
229 |
266 |
165 |
CDC Vanguard |
201 |
259 |
261 |
127 |
129 |
157 |
157 |
127 |
149 |
132 |
238 |
141 |
173 |
X05TH20-2 |
270 |
302 |
325 |
117 |
124 |
147 |
122 |
122 |
114 |
172 |
172 |
178 |
180 |
X05TH47-3 |
160 |
166 |
258 |
129 |
156 |
186 |
131 |
134 |
111 |
210 |
214 |
223 |
173 |
Dose Mean |
182 |
232 |
268 |
124 |
134 |
149 |
112 |
116 |
115 |
182 |
206 |
211 |
169 |
LSD0.05 |
51.9 |
72.9 |
58.1 |
30.0 |
29.6 |
39.8 |
40.9 |
37.7 |
36.4 |
55.9 |
53.9 |
71.7 |
48.2 |
The effects of locations, cultivars, and their interactions were significant on biomass (
Table 5). Moreover, the main effect of Fe fertilizer on biomass was highly significant (
p < 0.01). The highest biomass was obtained from cultivar CDC Frontier (196 g per plant) followed by CDC Cory (194 g per plant), whereas the lowest was found by CDC Alma (128 g per plant). The highest mean of biomass (268 g) was obtained with 30 kg ha
-1 of Fe fertilizer at Elrose in 2015. Biomass of the cultivars grown with no Fe fertilizer was significantly lower than the other two doses. However, some cultivars at Moose Jaw in 2015 obtained the highest biomass with no Fe fertilizer compared to the other two doses. For instance, cultivar CDC Luna had the highest biomass (102 g per plant) at 0 kg ha
-1 of Fe fertilizer compared to the other two doses (
Table 7).
3.2. Seed Fe
The mean seed Fe concentrations (mg kg
-1) of eighteen cultivars with three Fe fertilizer doses (0 kg ha
-1, 10 kg ha
-1, and 30 kg ha
-1) at both locations in 2015 and 2016 are presented in
Table 8.
Table 8.
Seed Fe concentrations (mg kg-1) of eighteen chickpea cultivars with three Fe fertilizer doses (0 kg ha-1, 10 kg ha-1, and 30 kg ha-1) at Elrose and Moose Jaw in 2015 and 2016.
Table 8.
Seed Fe concentrations (mg kg-1) of eighteen chickpea cultivars with three Fe fertilizer doses (0 kg ha-1, 10 kg ha-1, and 30 kg ha-1) at Elrose and Moose Jaw in 2015 and 2016.
|
Elrose |
Moose Jaw |
|
|
2015 |
2016 |
2015 |
2016 |
Cultivar |
Cultivars |
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
Mean |
1173-1 |
43 |
48 |
49 |
61 |
63 |
67 |
38 |
37 |
41 |
46 |
46 |
52 |
49 |
1460-2 |
47 |
52 |
54 |
56 |
60 |
61 |
39 |
39 |
44 |
45 |
44 |
50 |
49 |
AB06-156-2 |
51 |
52 |
57 |
67 |
70 |
71 |
41 |
43 |
41 |
47 |
49 |
55 |
54 |
Amit |
49 |
50 |
48 |
59 |
65 |
72 |
40 |
41 |
43 |
46 |
49 |
51 |
51 |
CA05-75-45 |
48 |
43 |
49 |
58 |
57 |
59 |
35 |
34 |
34 |
49 |
44 |
51 |
47 |
CDC Alma |
43 |
50 |
50 |
65 |
72 |
80 |
38 |
39 |
39 |
48 |
50 |
54 |
52 |
CDC Cabri |
46 |
46 |
54 |
57 |
57 |
60 |
37 |
40 |
40 |
47 |
48 |
51 |
49 |
CDC Consul |
52 |
52 |
54 |
57 |
63 |
57 |
42 |
47 |
43 |
41 |
44 |
47 |
50 |
CDC Corinne |
46 |
50 |
50 |
55 |
55 |
60 |
41 |
39 |
41 |
41 |
41 |
43 |
47 |
CDC Cory |
47 |
48 |
51 |
56 |
60 |
64 |
42 |
44 |
45 |
42 |
45 |
48 |
49 |
CDC Frontier |
57 |
55 |
55 |
66 |
73 |
76 |
43 |
45 |
46 |
49 |
52 |
57 |
56 |
CDC Leader |
48 |
47 |
45 |
60 |
60 |
62 |
38 |
37 |
39 |
43 |
46 |
53 |
48 |
CDC Luna |
48 |
47 |
48 |
78 |
73 |
80 |
38 |
39 |
37 |
49 |
56 |
56 |
54 |
CDC Orion |
46 |
53 |
52 |
70 |
68 |
71 |
39 |
37 |
40 |
47 |
52 |
54 |
52 |
CDC Palmer |
48 |
48 |
48 |
64 |
63 |
69 |
37 |
40 |
39 |
46 |
44 |
48 |
50 |
CDC Vanguard |
44 |
47 |
48 |
53 |
49 |
57 |
40 |
39 |
47 |
41 |
44 |
48 |
46 |
X05TH20-2 |
55 |
57 |
58 |
75 |
72 |
76 |
49 |
50 |
46 |
50 |
51 |
54 |
58 |
X05TH47-3 |
53 |
50 |
56 |
72 |
67 |
70 |
46 |
49 |
48 |
49 |
52 |
51 |
55 |
Dose Mean |
48 |
50 |
51 |
63 |
64 |
67 |
40 |
41 |
42 |
46 |
48 |
51 |
51 |
LSD0.05 |
7.0 |
11.4 |
7.6 |
9.6 |
11.6 |
9.3 |
4.9 |
4.8 |
5.5 |
7.1 |
5.5 |
6.8 |
7.6 |
The main effects of locations, years, and cultivars as well as their interactions were highly significant (
p < 0.01) on seed Fe concentrations (
Table 5). Moreover, significant differences were found among doses. Seed Fe concentrations obtained from Elrose in the year 2015 and 2016 were significantly higher than from Moose Jaw. The highest Fe concentration in seed was observed for cultivar X05TH20-2 (58 mg kg
-1) followed by CDC Frontier (56 mg kg
-1). Furthermore, the highest dose means (67 mg kg
-1) in seed Fe concentration was obtained at 30 kg ha
-1 of Fe fertilizer at Elrose in 2016 compared to all other doses at both locations in 2015 and at Moose Jaw in 2016. Seed Fe concentrations obtained from no Fe fertilizer was the lowest compared to the other two doses, except for cultivar X05TH47-3 at Elrose in 2016. The lowest dose means (40 mg kg
-1) in seed Fe concentration was observed under no Fe fertilizer treatment at Moose Jaw in 2015 compared to both locations in 2016 and Elrose in 2015 with other two doses (
Table 8).
3.3. Fe Yield
The mean of Fe yield (g ha
-1) of eighteen chickpea cultivars with three Fe fertilizer doses (0 kg ha
-1, 10 kg ha
-1, and 30 kg ha
-1) at both locations in 2015 and 2016 are presented in
Table 9.
Table 9.
The mean of Fe yield (g ha-1) of eighteen chickpea cultivars with three different doses (0 kg ha-1, 10 kg ha-1, and 30 kg ha-1) of Fe-EDDHA at Elrose and Moose Jaw in 2015 and 2016.
Table 9.
The mean of Fe yield (g ha-1) of eighteen chickpea cultivars with three different doses (0 kg ha-1, 10 kg ha-1, and 30 kg ha-1) of Fe-EDDHA at Elrose and Moose Jaw in 2015 and 2016.
Cultivars |
Elrose |
Moose Jaw |
|
2015 |
2016 |
2015 |
2016 |
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
0 kg ha-1
|
10 kg ha-1
|
30 kg ha-1
|
Cultivar Mean |
1173-1 |
311 |
347 |
316 |
129 |
116 |
31 |
86 |
83 |
111 |
141 |
131 |
170 |
164 |
1460-2 |
340 |
337 |
369 |
137 |
125 |
126 |
113 |
91 |
113 |
171 |
132 |
184 |
187 |
AB06-156-2 |
396 |
410 |
447 |
137 |
170 |
125 |
93 |
104 |
104 |
145 |
98 |
199 |
202 |
Amit |
306 |
337 |
335 |
132 |
113 |
174 |
93 |
86 |
89 |
132 |
150 |
150 |
175 |
CA05-75-45 |
305 |
250 |
311 |
160 |
132 |
138 |
74 |
59 |
61 |
112 |
171 |
126 |
158 |
CDC Alma |
234 |
250 |
247 |
62 |
65 |
63 |
89 |
79 |
109 |
. |
. |
. |
133 |
CDC Cabri |
291 |
326 |
319 |
284 |
172 |
187 |
74 |
99 |
90 |
152 |
72 |
107 |
181 |
CDC Consul |
430 |
405 |
419 |
172 |
171 |
135 |
132 |
127 |
129 |
196 |
253 |
291 |
238 |
CDC Corinne |
405 |
438 |
434 |
174 |
248 |
211 |
122 |
110 |
100 |
149 |
182 |
189 |
230 |
CDC Cory |
376 |
351 |
374 |
262 |
264 |
155 |
122 |
144 |
159 |
127 |
203 |
141 |
223 |
CDC Frontier |
443 |
433 |
427 |
130 |
150 |
314 |
140 |
131 |
131 |
78 |
62 |
75 |
209 |
CDC Leader |
359 |
420 |
367 |
152 |
135 |
69 |
98 |
104 |
104 |
190 |
156 |
165 |
193 |
CDC Luna |
282 |
294 |
291 |
149 |
112 |
141 |
100 |
107 |
110 |
. |
. |
. |
136 |
CDC Orion |
267 |
379 |
315 |
139 |
96 |
185 |
106 |
96 |
104 |
106 |
89 |
81 |
164 |
CDC Palmer |
416 |
342 |
422 |
190 |
206 |
204 |
97 |
95 |
98 |
173 |
170 |
300 |
226 |
CDC Vanguard |
272 |
372 |
288 |
168 |
151 |
156 |
105 |
95 |
94 |
108 |
97 |
104 |
167 |
X05TH20-2 |
263 |
334 |
306 |
109 |
97 |
147 |
85 |
92 |
83 |
104 |
98 |
109 |
152 |
X05TH47-3 |
346 |
367 |
387 |
133 |
182 |
113 |
103 |
141 |
123 |
198 |
153 |
209 |
205 |
Dose Mean |
335 |
355 |
354 |
157 |
150 |
148 |
102 |
102 |
106 |
135 |
131 |
155 |
186 |
LSD0.05 |
73.4 |
90.8 |
69.6 |
73.0 |
98.8 |
136.2 |
24.8 |
24.5 |
34.4 |
57.3 |
59.6 |
65.7 |
67.3 |
LSD = Least Significant DifferenceThere were significant differences in Fe yield among cultivars and doses. Fe yield obtained from Elrose in 2015 was significantly higher than other location and year. The highest cultivars mean for Fe yield was obtained from CDC Consul (238 g ha
-1) followed by CDC Corinne (230 g ha
-1). Furthermore, Fe fertilizer with a dose of 10 kg ha
-1 and 30 kg ha
-1 yielded the highest Fe yield of 355 g ha
-1 and 354 g ha
-1, respectively, at Elrose in 2015 compared to the Fe yield at both locations in 2016 and at Moose Jaw in 2015. Fe yield obtained from plants with no application of Fe fertilizer was the lowest than the other two doses for most cultivars. However, some cultivars were able to produce the highest Fe yield with low dose (0 kg ha
-1) of Fe fertilizer compared to the other two doses. For instance, cultivar 1173-1 had the highest Fe yield (129 g ha
-1) at 0 kg ha
-1 of Fe fertilizer (
Table 9).
4. Discussion
The application of synthetic Fe chelates on chickpeas across two years and two locations in Saskatchewan had significant effects (
p < 0.01) on biomass and seed Fe concentration (
Table 5). The chelate Fe fertilizer at 10 kg ha
-1 and 30 kg ha
-1 improved the seed Fe concentration across cultivars and environments. In 2015 and 2016, Elrose yielded higher levels of seed Fe concentration compared to Moose Jaw. Moreover, the highest seed Fe concentration (58.5 mg kg
-1) was obtained from CDC Frontier with 30 kg ha
-1 dose of chelate Fe fertilizer, whereas the lowest (44.5 mg kg
-1) was obtained from CDC Vanguard with no fertilizer application. At 30 kg ha
-1 Fe fertilizer, seed Fe concentration of CDC Frontier at Elrose and Moose Jaw in 2016 increased by 15% and 16%, respectively, compared to control. However, the seed Fe concentrations at different doses across environments only gained 5-11% increase compared to control. This suggests that the application of chelated Fe, which is the dominant form of Fe in the alkaline soil, provided readily available Fe to the roots of chickpea plants. Consequently, Fe concentration in seeds increased compared to control. Our findings are in agreement with findings of Moraghan et al. [
46] who reported that application of Fe-EDDHA increased seed Fe concentration in common bean. Moreover, the highest seed Fe concentration (65 mg kg
-1) was observed at Elrose in 2016 compared to the rest of the environments (
Table 8). The cultivars X05TH20-2 (58 mg kg
-1) and CDC Frontier (56 mg kg
-1) had the highest mean of seed Fe concentration compared to the rest of the cultivars, whereas CDC Vanguard had the lowest concentration (46 mg kg
-1). The variability in Fe concentrations was mostly attributed to cultivars across locations and years. Similar findings were previously reported in chickpea [
30].
Elrose location produced higher Fe yield compared to Moose Jaw in 2015 and 2016. The highest Fe yield (447 g ha
-1) was found on AB06-156-2 cultivar at 30 kg ha
-1 of chelate Fe fertilizer. At 30 kg ha
-1 fertilizer rate, Fe yield of AB06-156-2 cultivar at Elrose in 2015 increased by 12% compared to control. The overall Fe yield increased varying from 4 to19% in parallel with the Fe fertilizer doses across environments (
Table 9). Kumar et al. [
47] reported that the application of varying levels of Fe fertilizer up to 10 kg ha
-1 significantly increased Fe concentration in chickpea grain over control. Similar findings were also reported by Sharma et al. [
48] who observed that the application of chelated Fe fertilizer improved the Fe content in seeds of pigeon pea.
Locations, cultivars, and their interaction significantly affected biomass. The highest biomass (228 g per five plants) was observed at Elrose in 2015 compared to the rest of the environments. These findings are similar to those reported by Kumawat et al. [
49] and Sahu et al. [
50] who observed that soil-applied Fe fertilizer increased biomass yield in chickpea. Similarly, in cowpea, Mahriya and Meena [
51] reported that the application of Fe fertilizer improved biomass, which is consistent with our findings. Furthermore, the results are also similar to the findings of Bansal and Chahal [
52] who reported that application of 25 µg g
-1 Fe in mung bean grown in an alkaline soil significantly increased biomass and Fe content, which is in agreement with our findings. However, previous studies done in chickpea and soybean reported that application of Fe-EDDHA did not results in significant increase in biomass, which contrasts with our findings [
53,
54,
55].
The present study also showed that ascochyta blight disease affected the yield in both locations in 2016 (
Table S1.). The correlation analysis showed that ascochyta blight and yield were highly correlated (r = 0.75;
p < 0.01) at Moose Jaw in 2016 (
Table S2.). Due to ascochyta blight, Fe was most likely distributed to relatively a smaller number of plants that ultimately increased seed Fe concentration level at Moose Jaw location in 2016 compared to 2015. These findings suggested that the magnitude of the effects of ascochyta blight on seed Fe concentration depended on the cultivars and environments.
Other characteristics such as thousand seed weight, and seed yield varied significantly (
p < 0.01) among locations, years, cultivars, and their interactions in the two-year experiment (
Table 5). For thousand seed weight, both locations in 2015 produced larger seed size compared to 2016. This is mostly attributed to ascochyta blight disease that affected the plants in both locations in 2016 (
Table S1). As a result, thousand seed weight decreased. Moreover, the highest location means of thousand seed weight (363 g) was observed at Elrose in 2015, whereas the lowest (250 g) was found at Elrose in 2016 (
Table S3.). The highest grain yield (6904 kg ha
-1) was observed at Elrose in 2015, whereas the lowest (2421 kg ha
-1) was found at Elrose in 2016. CDC Corinne had the highest mean yield (4832 kg ha
-1), whereas CDC Alma had the lowest yield (2137 kg ha
-1) (
Table S4.). Mevada et al. [
56] also reported that the application of Fe chelates increased grain yield significantly over control in urdbean. Similar findings were also observed by Kumar et al. [
47] and Sahu et al. [
50] who reported that the application of Fe fertilizer increased grain yield of chickpea by 17.3%. Furthermore, thousand seed weight and seed yield were higher in resistant cultivars such as CDC Corinne, CDC Consul, CDC Leader, and CDC Frontier compared to the susceptible cultivars CDC Alma and CDC Luna. The variations in thousand seed weight and seed yield among cultivars could be due to the differences in their genetic constitution, physiology, and the cultivar response to various environmental conditions. Similar observations were also made by many authors in previous studies in chickpea and common bean [
57,
30].
The effects of Fe fertilizer on germination, node number, days to flowering, days to maturity, and plant height were not significant (
Table 1). However, locations, years, cultivars and their interactions significantly affected germination, node number, days to flowering, days to maturity, and plant height. Germination at both locations in 2015 was higher than in 2016. For instance, germination at Elrose in 2015 was 10% and 4% higher than in Elrose and Moose Jaw in 2016 However, node number, days to flowering, days to maturity, and plant height were higher at both locations in 2016 than 2015. The variations in the above-mentioned characteristics were mostly due to ascochyta blight infestation, cultivar response to various environmental conditions, genetics, and physiology. Current findings were consistent with previous studies in mung bean, chickpeas, common bean that showed application of Fe fertilizer did not improve vegetative growth attributes [
30,
47,
57,
58,
59]. However, previous studies in cowpea, black gram, and pea showed that growth characteristics were increased with the application of Fe fertilizer, which are in contrast with our findings [
60,
61,
62].