Climate condition
A significant difference was observed in the comparison of rainfall between two crop years. 2018-2019 crop year was wetter (310 mm) than 2019-2020 (254 mm) crop year. Also, the highest rainfall occurred in April in both crop years. The average minimum temperature ranged -2.53-17.76 °C and -4.56-15.65 °C in 2018-2019 and 2019-2020 crop years, respectively. The average maximum monthly temperature is between 9.04 °C in February and 36.5 °C in July in 2018-2019, and 8.75 °C in February and 33.56 °C in June in 2019-2020. No significant differences were observed between the two crop years. Also, the total radiation reached 70.59 MJ/m2 in 2018-2019 and 59.29 MJ/m2 in 2019-2020 (Table 3).
Table 3 Average minimum, maximum temperature, radiation and total monthly rainfall related to the growth period of wheat in Shirvan weather conditions during the two crop years (2018-2019 and 2019-2020).
|
Month/Year
|
Average minimum temperature (C°)
|
|
Average maximum temperature (C°)
|
|
Average radiation (MJ/m2)
|
|
Total rainfall (mm)
|
2018-19
|
2019-20
|
|
2018-19
|
2019-20
|
|
2018-19
|
2019-20
|
|
2018-19
|
2019-20
|
October
|
3.37
|
1.31
|
|
16.23
|
15.63
|
|
5.44
|
6.02
|
|
14.5
|
21.9
|
November
|
0.7
|
-1.63
|
|
11
|
10.22
|
|
3.83
|
4.15
|
|
41.1
|
10.4
|
December
|
-0.81
|
-3.50
|
|
9.07
|
9.12
|
|
5.28
|
4.71
|
|
14.6
|
5.4
|
January
|
-2.53
|
-4.56
|
|
9.04
|
8.75
|
|
6.003
|
5.47
|
|
34.7
|
10.6
|
February
|
-1.62
|
-0.06
|
|
12.69
|
14.95
|
|
5.97
|
6.04
|
|
45.2
|
63.6
|
March
|
6.06
|
3.99
|
|
17.40
|
15.12
|
|
5.07
|
4.79
|
|
99.8
|
94.7
|
April
|
7.96
|
8.26
|
|
23.49
|
23.31
|
|
8.37
|
7.26
|
|
30.1
|
44.2
|
May
|
12.3
|
11.92
|
|
29.42
|
33.56
|
|
9.29
|
10.89
|
|
24.9
|
1.8
|
June
|
17.76
|
15.65
|
|
36.5
|
32.85
|
|
21.34
|
9.96
|
|
5.1
|
1.4
|
Photosynthetic assimilate remobilization rate from flag leaf, peduncle and penultimate
In both crop years, there were no significant differences in photosynthetic assimilate remobilization rate from the flag leaf, peduncle and penultimate, while there was a significant difference between cultivars in photosynthetic assimilate remobilization rate in the mentioned traits. Also, the interaction effect of year and cultivar was significant in the mentioned traits (p≤0.01) (Table 4).
Table 4 Combined variance analysis of remobilization, The rate remobilization and The photosynthetic remobilization efficiency among different wheat cultivars in two crop years (2018-2019 and 2019-2020).
|
CV%
|
Error b
|
C ×Y
|
C
|
Error a
|
Y
|
S.O.V
|
Mean squares
|
-
|
60
|
15
|
15
|
4
|
1
|
Df
|
14.24
|
0.22
|
0.91**
|
4.64**
|
0.06
|
0.15ns
|
RFLA
|
10.21
|
3.71
|
22.31
|
184.16**
|
4.97
|
28.89ns
|
RFINO1
|
8.23
|
3.60
|
9.58**
|
97.43**
|
11.82
|
61.36ns
|
RFINO2
|
16.33
|
0.30
|
0.31**
|
4**
|
0.85
|
3.20ns
|
IRFLA
|
13.66
|
2.59
|
6.73**
|
140.09**
|
3.56
|
0.19ns
|
IRFINO1
|
16.14
|
6.32
|
11.68*
|
84.98**
|
10.47
|
120.66**
|
IRFINO2
|
14.44
|
3.17
|
12.56*
|
19.09ns
|
1.61
|
50.30ns
|
ERFLA
|
14.08
|
9.18
|
19.91*
|
89.50**
|
3.43
|
0.77ns
|
ERINO1
|
7.53
|
3.61
|
10.46**
|
25.54**
|
13.34
|
10.82ns
|
ERFINO2
|
15.39
|
0.44
|
2.44
|
2.50**
|
1.55
|
23.93**
|
GY
|
RFLA: The remobilization rate from flag leaf; RFINO1: The remobilization rate from peduncle; RFINO2: The remobilization rate from penultimate; IRFLA: The remobilization contribution from flag leaf, IRFINO1: The remobilization contribution from peduncle; IRFINO2: The remobilization contribution from penultimate; IRFINO2: The remobilization efficiency from flag leaf; ERINO1: The remobilization efficiency from peduncle; ERFINO2: The remobilization efficiency from penultimate; GY: Grain yield.
The highest and lowest photosynthetic assimilate remobilization rate from the flag leaf was 6.99 and 2.02 g/m2 in the first year, respectively, while it was 4.63 and 1.78 g/m2 in the second year, respectively. Also, the highest and lowest photosynthetic assimilate remobilization rate from the peduncle were 34.80 and 10.45 g/m2 in the first year, and 28.35 and 11.36 g/m2 in the second year, respectively. The highest and lowest photosynthetic assimilate remobilization rate from penultimate were 37.64 and 20.11 g/m2 in the first year, and 29.49 and 20.02 g/m2 in the second year, respectively (Table 5). Calculating the linear regression relationship between these traits and the cultivar release year showed that these traits have improved during the breeding activity in the last 26 years, but photosynthetic assimilate remobilization rate from flag leaf and peduncle had a higher upward trend compared to penultimate. In other words, the increase in remobilization rate from the flag leaf, peduncle and penultimate was 228.24, 224.12 and 132.76 % in the last two decades, respectively, so that, increase in remobilization rate from flag leaf, peduncle and penultimate were observed 8.77, 8.62 and 5.1% for each year of release (Figure 1).
Table 5 Mean comparison of assimilate remobilization, the assimilate remobilization contribution and the photosynthetic assimilate remobilization efficiency in different wheat cultivars in two crop years (2018-2019 and 2019-2020).
Y
|
C
|
RFLA
|
RFINO1
|
RFINO2
|
IRFLA
|
IRFINO1
|
IRFINO2
|
ERFLA
|
ERINO1
|
ERFINO2
|
GY
|
|
Ve
|
2.23
|
14.75
|
20.77
|
0.54
|
3.38
|
5.07
|
9.38
|
19.93
|
25
|
4.10
|
At
|
2.55
|
12.39
|
21.45
|
0.62
|
3.02
|
5.23
|
10.38
|
17.71
|
24.14
|
4.10
|
Pa
|
2.45
|
16.06
|
2.14
|
0.69
|
4.37
|
6.01
|
9.87
|
22.63
|
23.09
|
3.69
|
Za
|
2.10
|
20.35
|
21.10
|
0.58
|
5.57
|
5.78
|
7.94
|
23.08
|
24.12
|
3.65
|
Go
|
2.35
|
15.69
|
22.07
|
0.59
|
4.48
|
6.34
|
8.86
|
20.28
|
26.75
|
3.49
|
Sh
|
2.02
|
18.25
|
21.31
|
0.47
|
3.61
|
4.97
|
7.60
|
23.82
|
25.80
|
4.29
|
N8019
|
3.25
|
14.17
|
21.65
|
0.87
|
3.78
|
5.77
|
11.27
|
16.60
|
24.56
|
3.75
|
LA
|
3.15
|
10.45
|
20.11
|
0.97
|
3.24
|
6.20
|
13.94
|
11.91
|
22.78
|
3.24
|
L17
|
3.77
|
13.60
|
20.18
|
0.99
|
3.58
|
5.27
|
13.20
|
16.87
|
22.52
|
3.82
|
Me
|
3.52
|
17.65
|
22.29
|
1.01
|
5.10
|
6.36
|
11.59
|
19.84
|
26.90
|
3.50
|
Ar
|
4.09
|
20.63
|
23.04
|
0.96
|
4.84
|
5.41
|
13.32
|
24.50
|
23.64
|
4.26
|
Mor
|
3.99
|
20.78
|
23.76
|
1.07
|
5.59
|
6.38
|
13.34
|
23.07
|
28.05
|
3.72
|
Ka
|
4.07
|
23.99
|
29.25
|
1.27
|
7.49
|
9.13
|
12.86
|
24.88
|
28.50
|
3.23
|
Gon
|
5.21
|
31.87
|
28.85
|
0.91
|
5.60
|
5.06
|
15.56
|
31.11
|
27.91
|
5.69
|
Eh
|
6.99
|
34.80
|
37.64
|
1.21
|
6.05
|
6.54
|
17.61
|
31.15
|
31.27
|
5.75
|
|
Mean
|
3.45
|
19.03
|
23.71
|
0.84
|
4.63
|
6.08
|
11.78
|
21.83
|
25.67
|
3.92
|
|
LSD0.05
|
0.75
|
3.86
|
2.84
|
0.76
|
2.91
|
4.20
|
2.76
|
6.47
|
2.57
|
1.43
|
|
Ve
|
2.40
|
12.76
|
20.65
|
0.65
|
3.38
|
5.49
|
11.59
|
18.86
|
26.35
|
3.78
|
At
|
1.78
|
11.36
|
19.42
|
0.50
|
3.17
|
5.41
|
9.70
|
15.82
|
23.55
|
3.59
|
Pa
|
2.89
|
13.19
|
21.39
|
0.69
|
3.16
|
5.14
|
12.58
|
19.25
|
26.41
|
4.16
|
Za
|
2.93
|
19.60
|
20.67
|
0.74
|
4.96
|
5.23
|
11.56
|
22.26
|
25.04
|
3.95
|
Go
|
3.62
|
20.79
|
21.44
|
0.92
|
5.28
|
5.44
|
15.27
|
22.35
|
24.74
|
3.94
|
Sh
|
3.39
|
20.54
|
22.54
|
0.85
|
5.16
|
5.66
|
15.13
|
21.71
|
25.37
|
3.99
|
N8019
|
3.74
|
20.43
|
20.15
|
0.94
|
5.13
|
5.07
|
15.04
|
21.81
|
22.03
|
3.99
|
LA
|
2.87
|
18
|
22.61
|
0.68
|
4.24
|
5.32
|
12.34
|
19.39
|
26.37
|
4.25
|
L17
|
3.09
|
17.10
|
16.65
|
0.64
|
3.52
|
3.43
|
12.86
|
19.35
|
20.19
|
4.86
|
Mo
|
3.27
|
21.91
|
20.01
|
0.74
|
4.99
|
4.56
|
13.73
|
22.26
|
20.88
|
4.39
|
Ar
|
3.50
|
0.91
|
22.57
|
0.76
|
4.51
|
4.88
|
12.73
|
22.28
|
25.06
|
4.63
|
Mor
|
3.59
|
23.41
|
22.74
|
0.91
|
5.94
|
5.77
|
13.29
|
23.99
|
24.07
|
3.94
|
Ka
|
3.77
|
26.02
|
28.02
|
0.95
|
6.58
|
7.09
|
13.10
|
26.61
|
27.40
|
3.95
|
Gon
|
4.34
|
24.99
|
31.11
|
1.07
|
6.18
|
7.70
|
14.16
|
24.81
|
29.15
|
4.04
|
Eh
|
4.63
|
28.35
|
29.49
|
1
|
6.10
|
6.35
|
14.81
|
26.12
|
27.80
|
4.65
|
|
Mean
|
3.26
|
19.43
|
22.24
|
0.82
|
4.82
|
5.52
|
13.06
|
21.60
|
24.90
|
4/08
|
|
LSD0.05
|
0.82
|
2.41
|
3.46
|
0.74
|
2.45
|
4.19
|
3.17
|
3.04
|
3.67
|
0.59
|
RFLA: The remobilization rate from flag leaf (gr/m2); RFINO1: The remobilization rate from peduncle (gr/m2); RFINO2: The remobilization rate from penultimate (gr/m2); IRFLA: The remobilization contribution from flag leaf (gr/m2), IRFINO1: The remobilization contribution from peduncle (gr/m2); IRFINO2: The remobilization contribution from penultimate (gr/m2); IRFINO2: The remobilization efficiency from flag leaf (%); ERINO1: The remobilization efficiency from peduncle (%); ERFINO2: The remobilization efficiency from penultimate (%); GY: Grain yield (gr/m2).
The contribution of photosynthetic assimilate remobilization from flag leaf, peduncle and penultimate in grain yield
the contribution of photosynthetic assimilate remobilization in the grain yield from the flag leaf and peduncle were not difference in the two crop years, but it was significant from penultimate to grain yield in both years. Also, the cultivar effect and the interaction effect of cultivar × year on the mentioned traits were significant (Table 4). The contribution of photosynthetic assimilate remobilization from the flag leaf in the grain yield was different from 0.47% in the Shiroudi cultivar to 5.63% in the Ehsan cultivar in the first year, and from 0.50% in the Atrak cultivar to 4.78% in the Ehsan cultivar in the second year. The average contribution of photosynthetic assimilate remobilization to the grain yield from flag leaf in the first and second crop years were 0.84% and 0.82%, respectively (Table 5). The average changes of this trait during 26 years of breeding activity in Iran showed a significant increasing trend, in other words, an 80.81% increase was observed in the contribution of photosynthetic assimilate remobilization from the flag leaf, so that the contribution of photosynthetic assimilate remobilization increased by 10.3% from the flag leaf in each year of release (Figure 2a).
The contribution of photosynthetic assimilate remobilization from peduncle in different cultivars varied 3.02-7.49% in the first year and 3.17-6.58% in the second year. Also the average contribution of photosynthetic assimilate remobilization from peduncle in cultivars was 4.63 and 4.82 in the first and second year, respectively (Table 5). Evaluating the relationship between this trait and the year of cultivar release indicated that the contribution of photosynthetic assimilate remobilization from peduncle in grain yield has been increasing during the crop breeding activities in the past years. In other words, the contribution of photosynthetic assimilate remobilization from peduncle increased 192.34% in the past 26 years, so that, 39.7% increase was observed in the contribution of photosynthetic assimilate remobilization from the peduncle in each year of release (Figure 2b).
The mean comparison between cultivars in two crop years showed that there was a significant difference between cultivars in terms of photosynthetic assimilate remobilization contribution from penultimate to grain yield. The range of changes in the contribution of photosynthetic assimilate remobilization from penultimate to grain yield was 4.97%-9.13% in the first year and 3.43%-7.70% in the second year. The average contribution of photosynthetic assimilate remobilization from penultimate to grain yield in the first and second year were 6.08% and 5.52%, respectively (Table 5). Hence, it can be seen that the contribution of photosynthetic assimilate remobilization from penultimate in grain has been on the rise in recent years in these cultivars, so that the contribution of photosynthetic assimilate remobilization from penultimate has increased by 20.49% in the last two decades. 73.5% increase in the contribution of photosynthetic assimilate remobilization from penultimate was observed for each year of release (Figure 2c).
The photosynthetic assimilate remobilization efficiency from flag leaf, peduncle and penultimate
The results indicated that the effect of cultivar on the photosynthetic assimilate remobilization efficiency from peduncle and penultimate and the interaction effect of cultivar and year on the photosynthetic assimilate remobilization efficiency from flag leaf, peduncle and penultimate were significant (Table 4). The range of changes in the photosynthetic assimilate remobilization efficiency from the flag leaf varied from 60.7 to 17.61% the first year and in the second year from 9.70 to 14.81% respectively. Also the average photosynthetic assimilate remobilization efficiency from the flag leaf was 11.78% and 13.06% in the first and second years, respectively. Evaluating the relationship between the photosynthetic assimilate remobilization efficiency from the flag leaf and the year of cultivar release revealed that the photosynthetic assimilate remobilization efficiency from the flag leaf has increased (by 50.93%) significantly over the past 26 years. In other words, it has increased by 80.5%for each year of release (Figure 3a).
The mean comparison of photosynthetic assimilate remobilization efficiency showed that the highest and lowest remobilization efficiency from the peduncle was 31.15 and 11.91 in the first year, and 26.61 and 15.82 in the second year, respectively. Also, the highest and lowest remobilization efficiency from penultimate were 31.27 and 22.52 in the first year, and 29.15 and 22.52 in the second year, respectively (Table 5).
Examining the relationship between these traits and the cultivar release year showed that it has been increasing trend during the plant breeding activities. In other words, increasing the remobilization efficiency from the peduncle and penultimate by 151.38 and 109.09 percent in the past 26 years, respectively. Indeed, it has increased by 5.28% and 4.19% for each release year, respectively (Figure 3 b and c). However, the increase in the photosynthetic assimilate remobilization efficiency from the peduncle and penultimate was less than that of the flag leaf.
Grain yield
The effect of year, cultivar and interaction effect of year × cultivar on grain yield were significant (P≤0.05). The mean comparison between cultivars showed that there was a significant difference between cultivars in terms of grain yield per unit area in both crop years. The range of grain yield changes was 3.50-5.75 t/ha 3.59-4.86 t/ha in the first and second years, respectively (Table 5). However, no significant difference was observed between the two crop years in terms of grain yield. Evaluating the relationship between grain yield and the cultivar release year indicated that grain yield has been improved during the past 26 years. In other words, the grain yield has increased by 102.01% during these past years, so that it is 3.92% increase in grain yield was observed for each year of release, (Figure 4).