Plant Height (cm)
According to 2017 data, the highest average plant height was 79.70 cm at the second harvest time and the lowest average plant height was 59.70 cm at the first harvest time. There was no statistical difference between plant densities on plant height. The difference was found to be statistically insignificant in terms of harvest time x plant density interaction and plant height values ranged between 57.31 cm and 82.31 cm. When the second year data were analysed, except for the harvest time averages, other treatments were found to be statistically significant and formed different groups. The highest values of 86.00 and 82.50 cm were obtained from 25 x 50 cm frequency (Table 1).
Table 1
Mean Values of Plant Height of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Plant Density (cm)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
60.63
|
82.31
|
71.47
|
82.50 ab
|
86.00 a
|
84.25 A
|
30x50 cm
|
57.31
|
76.81
|
67.06
|
79.00 abc
|
78.00 abc
|
78.50 AB
|
35x50 cm
|
61.13
|
79.88
|
70.50
|
75.50 abc
|
73.25 bc
|
74.38 BC
|
40x50 cm
|
59.75
|
79.81
|
69.78
|
67.75 c
|
71.25 bc
|
69.50 C
|
Averages
|
59.70 B
|
79.70 A
|
|
76.19
|
77.13
|
|
LSD (0,05)
|
Harvest time* (5.076), Plant density (NS), Interaction (NS)
|
Harvest time (NS), Plant density* (8.25), Interaction (NS)
|
As a result of the research, although the plant height values were not found to be statistically significant in the first year, it was observed that it tended to increase with increasing plant density in general. The reason for this is thought to be due to the fact that the plants are in competition to reach sunlight. The fact that the plant height in the second harvest is longer than the first harvest is thought to be due to the slow development of the seedlings at the time of the first planting, the plant height of the plants growing in shady environments is longer than the plants growing in the sun, the plant height increases in parallel with the number of days as the plant moves away from the first planting time, and after the first harvest, the plant begins to utilise nutrients and water more regularly. The findings obtained were lower than those of Klienle (1993), Casaccia and Alvarez (2006), in parallel with the findings of Burling (2007), Lankes and Pude (2008), Taleie et al. (2012), Samadpourrigani (2014), Yıldırım (2017) and higher than those of Shyu (1994), Valois (2002), Megeji et al. (2005).
Fresh herb weight per plant (g plant − 1 )
According to 2017 data, the highest average fresh herb weight per plant was determined at the second harvest time with 60.31 g plant− 1 and the lowest average fresh herb weight per plant was determined at the first harvest time with 33.38 g plant− 1. The average fresh herb weight per plant between plant densities varied between 51.31 g plant− 1 and 42.44 g plant− 1. Accordingly, the highest average fresh herb weight per plant was 51.31 g plant− 1 at 25x50 cm plant density and the lowest average fresh herb weight per plant was 42.44 g plant− 1 at 40x50 cm plant density.
Table 2
Mean Values of Fresh Herb Weight Per Plant of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Fresh Herb Weight Per Plant (g plant− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
39.83 c
|
62.79 a
|
51.31 A
|
50.84 a
|
52.24 a
|
51.54 A
|
30x50 cm
|
37.16 c
|
62.75 a
|
49.96 A
|
47.62 b
|
41.93 c
|
44.77 B
|
35x50 cm
|
32.17 d
|
55.21 b
|
43.69 B
|
42.94 c
|
36.06 d
|
39.50 C
|
40x50 cm
|
24.38 e
|
60.50 a
|
42.44 B
|
41.96 c
|
34.44 d
|
38.20 D
|
Averages
|
33.38 B
|
60.31 A
|
|
45.84 A
|
41.17 B
|
|
LSD (0,05)
|
Harvest time* (4.322), Plant density* (2.342), Interaction* (3.312)
|
Harvest time* (0.98), Plant density* (1.19), Interaction* (1.68)
|
According to the harvest time x plant density interaction, the highest fresh herb weight per plant was 62.79 g plant− 1 at 25x50 cm plant density in the second harvest period and the lowest fresh herb weight per plant was 24.38 g plant− 1 at 40x50 cm plant density in the first harvest. When the second year data were analysed, it was observed that the first harvest value was higher than the second harvest value averages. This is thought to be due to the fact that the plants which were in the young seedling stage in the first harvest in the first year, developed and became robust in the second year and closed the difference between the harvest periods. The second year plant density averages were higher in the treatments with dense plant density as in the first year (Table 2). As a result of the research, the values of fresh herb weight per plant were found to be statistically significant, and it was observed that as the plant density increased and the harvest time was delayed, plant height increased and leaf yield tended to increase (Midmore and Rank 2002). The fact that the increase in fresh herb weight per plant in the second harvest was higher than the first harvest is thought to be due to the slow growth of the seedlings at the first planting time. The reason for this is that leaf yield, plant height, number of branches, number of leaves per plant and dry matter accumulation are related to each other (Chalapathi et al. 1998) and the differences between the values obtained related to the delay of harvest time are thought to be due to the amount of organic matter in the soil where the plant is grown, the amount of nutrients available from the soil and the water balance. The findings obtained in this study are lower than the findings of Samadpourrigani (2014) and in parallel with the findings of Sözmen (2015), Gedik and Tansı (2017) for three and four year old plants.
Fresh branch weight per plant (g plant − 1 )
According to 2017 data, it was determined that the average fresh branch weight per plant varied between 12.35 g plant− 1 and 32.81 g plant− 1 between harvest times. The highest average fresh branch weight per plant was determined at the second harvest time with 32.81 g plant− 1 and the lowest was determined at the first harvest time with 12.35 g plant− 1. Among the plant densities, the highest mean fresh branch weight per plant was obtained at 30x50 cm plant density with 23.71 g plant− 1 and the lowest mean fresh branch weight per plant was obtained at 25x50 cm plant density with 20.10 g plant− 1.
Table 3
Mean Values and Resulting Groups of Fresh Branch Weight Per Plant of Stevia at Different Plant Densities and Different Harvest Times
|
Fresh Branch Weight Per Plant (g plant− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
14.88 d
|
25.33 c
|
20.10 B
|
20.55 bc
|
29.24 a
|
24.90 A
|
30x50 cm
|
14.42 d
|
33.00 b
|
23.71 A
|
19.20 cde
|
22.01 b
|
20.61 B
|
35x50 cm
|
11.42 e
|
34.75 b
|
23.08 A
|
17.69 de
|
19.75 bcd
|
18.72 C
|
40x50 cm
|
8.71 f
|
38.17 a
|
23.44 A
|
17.27 e
|
18.75 cde
|
18.01 C
|
Averages
|
12.35 B
|
32.81 A
|
|
18.68 B
|
22.44 A
|
|
LSD (0,05)
|
Harvest time** (1.6962), Plant density* (1.6897), Interaction** (2.3896)
|
Harvest time* (1.68), Plant density* (1.74), Interaction* (2.46)
|
According to the harvest time x plant density interaction, the highest fresh branch weight per plant was 38.17 g plant− 1 at 40x50 cm plant density in the second harvest period and the lowest fresh branch weight per plant was 8.71 g plant− 1 at 40x50 cm plant density in the first harvest period. In the first harvest period, it was determined that as the plant density increased and the harvest time delayed, the fresh branch weight per plant increased. In the second harvest period, the highest fresh branch weight per plant was obtained at 40x50 cm plant density and the lowest fresh branch weight per plant was obtained at 25x50 cm plant density. When the second year data were analysed, it was seen that the highest value was obtained from 25 x 50 cm plant density in both the first and second harvests and in the average values of both harvests. In addition, the average of the second harvest was higher than the first harvest. The findings obtained from the number of branches per plant support the results. Under normal conditions, the number of branches is expected to decrease as the plant density increases, but due to the effect of genetic characteristics and environment, the highest number of branches and therefore the highest number of branches per plant weight was obtained from 25 x 50 cm plant density (Table 3). As a result of the research, the values of fresh branch weight per plant in the first year were found to be statistically significant. At 25x50 cm plant density, fresh branch weight per plant was found to be low, and as the plant density increased, fresh branch weight per plant decreased. The reason for this is thought to be the decrease in the number of branches with the increase in plant height. The increase in fresh branch weight at the second harvest time is due to the development of the stem of the plant and hardening of the stem as the vegetation period of the plant increases. The findings of this study are higher than those of Khan et al. (2012), lower than those of Taleie et al. (2012) and Samadpourrigani (2014).
Number of Branches per Plant (pcs/plant)
When the second year data were analysed, it was observed that the number of branches decreased as the plant population decreased in both harvest times and harvest time averages, and the second harvest time averages were higher. The results are in parallel with the fresh branch weight per plant (Table 4). According to 2017 data, it was determined that the average number of branches per plant varied between 1.94 pieces/plant and 11.31 pieces/plant between harvest times. The highest average number of branches per plant was determined at 25x50 cm plant density with 7.79 pieces/plant and the lowest average number of branches per plant was determined at 40x50 cm plant density with 5.67 pieces/plant.
Table 4
Mean Values of Number of Branches per Plant of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Number of Branches per Plant (pcs/plant)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
1.71
|
13.88
|
7.79
|
4.12 ab
|
4.25 a
|
4.19 A
|
30x50 cm
|
2.13
|
12.00
|
7.06
|
2.75 e
|
3.25 cde
|
3.00 B
|
35x50 cm
|
1.88
|
10.08
|
5.98
|
2.81 e
|
3.63 bc
|
3.22 B
|
40x50 cm
|
2.04
|
9.29
|
5.67
|
2.94 e
|
3.51 cd
|
3.23 B
|
Averages
|
1.94 B
|
11.31 A
|
|
3.16 B
|
3.66 A
|
|
LSD (0,05)
|
Harvest time** (1.41), Plant density* (0.94), Interaction* (1.33)
|
Harvest time* (0.48), Plant density* (0.43), Interaction (ns)
|
In terms of harvest time x plant density interaction, the number of branches per plant varied between 13.88 pieces/plant and 1.71 pieces/plant. Accordingly, the highest average number of branches per plant was 13.88 pieces/plant at 25x50 cm plant density in the second harvest period and the lowest average number of branches per plant was 1.71 pieces/plant at 25x50 plant density in the first harvest. As a result of the research, it is thought that the increase in the number of branches per plant in the second harvest is higher than the first harvest is due to the slow development of the seedlings at the first planting time. The reason for this is thought to be the awakening of the sleeping eyes in the leaf axils after mowing and the increase in the number of branches per plant as the harvest time is delayed. The findings obtained are in parallel with the findings of Samadpourrigani (2014), Sözmen (2015), Yıldırım (2017).
Dry herb weight per plant (g plant − 1 )
According to 2017 data, the difference between plant densities in terms of dry herb weight per plant in both years was found statistically significant and two different groups were formed. Accordingly, the average dry herb weight per plant between plant densities varied between 14.75 g plant− 1 and 11.42 g plant− 1 in the first year and between 18.75 g plant− 1 and 13.68 g plant− 1 in the second year (Table 5).
Table 5
Mean Values of Dry Herb Weight Per Plant of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Dry Herb Weight Per Plant (g plant− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
10.71 d
|
18.79 a
|
14.75 A
|
16.93 b
|
20.56 a
|
18.75 A
|
30x50 cm
|
10.25 d
|
18.46 ab
|
14.35 A
|
15.18 d
|
17.40 b
|
16.29 B
|
35x50 cm
|
8.96 e
|
16.79 c
|
13.88 B
|
13.38 f
|
16.15 c
|
14.76 C
|
40x50 cm
|
6.96 f
|
16.88 b
|
11.42 B
|
13.12 f
|
14.25 e
|
13.68 D
|
Averages
|
9.22 B
|
17.98 A
|
|
14.65 B
|
17.09 A
|
|
LSD (0,05)
|
Harvest time* (0.88), Plant density* (0.62), Interaction* (0.87)
|
Harvest time* (0.71), Plant density* (0.51), Interaction* (0.72)
|
According to different plant densities, the highest average dry herb weight per plant was 14.75 g plant− 1 at 25x50 cm plant density and the lowest average dry herb weight per plant was 11.42 g plant− 1 at 40x50 cm plant density. According to the first year harvest time x plant density interaction, the highest dry herb weight per plant was obtained 18.79 g plant− 1 at 25x50 cm plant density in the second harvest period and the lowest dry herb weight per plant was obtained 6.96 g plant− 1 at 40x50 cm plant density in the first harvest period. As a result of the research, dry herb weight per plant values were found to be statistically significant in both years, as the plant density increased, fresh herb weight per plant values increased, and it was observed that dry herb values increased in parallel with the increase in fresh herb weight values. It is thought that the reason why the increase in dry herb weight per plant in the second harvest is higher than the first harvest is that as the harvest time is delayed, the leaves of the plant provide more nutrients in the plant and more dry herb is obtained in the second harvest due to hardening and carding of the leaves. The reason for this is thought to be the increase in dry herb weight depending on the fresh herb weight per plant as the harvest time is delayed. The findings obtained are lower than the findings of Samadpourrigani (2014) and parallel to the findings of Sözmen (2015), Gedik and Tansı (2017) in three and four year old plants.
Dry branch weight per plant (g plant − 1 )
According to 2017 data, the highest average dry branch weight per plant was determined at the second harvest time with 10.27 g plant− 1 and the lowest average dry herb yield was determined at the first harvest time with 3.08 g plant− 1. The highest average of dry branch weight per plant was 7.24 g plant− 1 at 30x50 cm plant density and the lowest average of dry branch weight per plant was 5.65 g plant− 1 at 25x50 cm plant density.
Table 6
Mean Values of Dry Branch Weight per Plant of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Dry Branch Weight per Plant (g plant− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
3.29 d
|
8.00 c
|
5.65 C
|
5.76 bc
|
10.57 a
|
8.16 A
|
30x50 cm
|
3.25 d
|
11.23 a
|
7.24 A
|
5.29 cd
|
7.03 b
|
6.02 B
|
35x50 cm
|
3.42 d
|
10.46 b
|
6.94 AB
|
4.63 cd
|
6.75 b
|
5.83 BC
|
40x50 cm
|
2.38 e
|
11.38 a
|
6.88 B
|
4.11 d
|
5.93 bc
|
5.02 C
|
Averages
|
3.08 B
|
10.27 A
|
|
4.95 B
|
7.57 A
|
|
LSD (0,05)
|
Harvest time** (0.46), Plant density** (0.35), Interaction** (0.50)
|
Harvest time* (0.58), Plant density* (0.98), Interaction* (1.39)
|
According to the harvest time x plant density interaction, the highest dry branch weight per plant was obtained 11.38 g plant− 1 at 40x50 cm plant density in the second harvest period and the lowest dry branch weight per plant was obtained 2.38 g plant− 1 at 40x50 cm plant density in the first harvest period. In 2017, as a result of the research, dry branch weight per plant values were found to be statistically significant, and as the plant density increased, dry branch weight per plant decreased in relation to fresh branch weight per plant. This is thought to be due to the decrease in the number of branches in the plant with the increase in plant height. The increase in dry branch weight at the second harvest time is thought to be due to the higher dry branch weight per plant obtained due to the development, hardening and carding of the stem of the plant as the vegetation period of the plant extends. In 2018, in both harvest time and plant density averages, the values were higher as the plant density increased. When we look at the harvest time averages, the second harvest time was found to be higher as in the first year. Normally, as time passed, the plants developed and the branches developed in parallel (Table 6). The findings of the study were lower than the findings of Taleie et al. (2012), Samadpourrigani (2014), Gedik and Tansı (2017) obtained from three and four year old plants, and parallel to the findings of Kumar et al. (2013).
Fresh Branch Yield (kgha − 1 )
According to 2017 data, the highest average fresh branch yield per plant was determined at the second harvest time with 208.67 kgha− 1 and the lowest fresh branch yield average was determined at the first harvest time with 825.1 kgha− 1. The lowest fresh branch yield average was determined at the first harvest time. The highest fresh branch yield average among plant densities was obtained with 1608.3 kgha− 1 at 25x50 cm plant density, while the lowest fresh branch yield average was obtained with 1249.9 kgha− 1 at 40x50 cm plant density. According to the interactions of harvest time x plant density, the highest fresh branch yield was obtained 2199.8 kgha− 1 at 30x50 cm plant density in the second harvest period and the lowest fresh branch yield was obtained 464.4 kgha− 1 at 40x50 cm plant density in the first harvest period. In the first harvest period, the highest fresh branch yield was obtained at 25x50 cm plant density, while the lowest fresh branch yield was obtained at 40x50 cm plant density.
Table 7
Mean Values of Fresh Branch Yield of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Fresh Branch Yield (kgha− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
1190.0 c
|
2026.6 b
|
1608.3 A
|
1644.3 bc
|
2339.3 a
|
1991.8 A
|
30x50 cm
|
961.1 d
|
2199.8 a
|
1580.4 A
|
1279.7 d
|
1761.0 b
|
1520.3 B
|
35x50 cm
|
685.1 e
|
2085.0 ab
|
1385.0 B
|
1061.3 e
|
1580.0 bc
|
1320.6 C
|
40x50 cm
|
464.4 f
|
2035.5 b
|
1249.9 C
|
920.9 e
|
1500.0 bc
|
1210.5 C
|
Averages
|
825.1 B
|
2086.7 A
|
|
1226.5 B
|
1795.1 A
|
|
LSD (0,05)
|
Harvest time** (101.5), Plant density** (111.5), Interaction** (157.7)
|
Harvest time* (134.6), Plant density* (133.4), Interaction (ns)
|
In the first harvest period, it was determined that fresh branch yield increased as the plant density increased and the harvest time was delayed. In the second harvest period, the highest fresh branch yield was recorded at 30x50 cm plant density, while the lowest fresh branch yield was recorded at 25x50 cm plant density. When the second year yields were analysed, it was found that as the plant density increased, the fresh branch yield increased in both harvest periods and plant density averages, and the harvest time averages showed higher results in the second harvest period as in the first year (Table 7). As a result of the research, fresh branch yield values were found to be statistically significant, fresh branch yield increased with the increase in the number of plants per unit area (Taleie et al. 2012), and as the plant density increased and the harvest time was delayed, fresh branch yield also increased. The increase in fresh branch yield at the second harvest time is due to the fact that as the vegetation period of the plant is prolonged, more nutrients are formed in the stem of the plant, and more fresh branch yield was obtained in the second harvest due to hardening and carding in the stem. This is thought to be due to the increase in plant density and the number of plants per decare. The findings obtained in this study are lower than the findings of Taleie et al. (2012), Samadpourrigani (2014).
Fresh leaf weight per plant (g plant − 1 )
According to 2017 data, the highest average fresh leaf weight per plant was determined at the second harvest time with 21.51 g plant− 1 and the lowest average fresh leaf weight per plant was determined at the first harvest time with 20.46 g plant− 1. The highest mean fresh leaf weight per plant was 22.83 g plant− 1 at 25x50 cm plant density and the lowest mean fresh leaf weight per plant was 18.56 g plant− 1 at 40x50 cm plant density.
Table 8
Mean Values of Fresh Leaf Weight Per Plant of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Fresh Leaf Weight Per Plant (g plant− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
24.09 a
|
21.58 bc
|
22.83 A
|
28.28 a
|
24.25 c
|
26.26 A
|
30x50 cm
|
21.96 b
|
21.59 bc
|
21.77 AB
|
26.77 b
|
19.06 d
|
22.92 B
|
35x50 cm
|
20.21 c
|
21.33 bc
|
20.77 B
|
25.56 bc
|
15.56 e
|
20.56 C
|
40x50 cm
|
15.59 d
|
21.54 bc
|
18.56 C
|
25.80 b
|
15.69 e
|
20.74 C
|
Averages
|
20.46
|
21.51
|
|
26.60 A
|
18.64 B
|
|
LSD (0,05)
|
Harvest time (ns), Plant density** (1.13), Interaction** (1.60)
|
Harvest time* (0.81), Plant density* (0.98), Interaction* (1.38)
|
According to the interactions of harvest time x plant density, the highest fresh leaf weight per plant was 24.09 g plant− 1 at 25x50 cm plant density in the first harvest period and the lowest fresh leaf weight per plant was 15.59 g plant− 1 at 40x50 cm plant density in the first harvest period. The highest fresh leaf weight per plant was obtained at 25x50 cm plant density, while the lowest fresh leaf weight per plant was obtained at 40x50 cm plant density in the first harvest period. It was determined that as the plant density increased, fresh leaf weight per plant increased as the harvest time was delayed. In the second harvest period, the highest fresh leaf weight per plant occurred at 40x50 cm plant density, while the lowest fresh leaf weight per plant occurred at 25x50 cm plant density. When the data obtained in the second year are analysed, it will be seen that, as in the first year, fresh leaf weight per plant increased as the plant density increased and decreased as the population decreased in the first harvest time, second harvest time results and average results. When the averages of harvesting times were analysed, although there was no statistical difference in the first year, the data of the first harvesting time in the second year were higher than the data of the second harvesting time (Table 8). It can be concluded that as the number of plants per unit area increased, the number of fresh leaves also increased. As a result of the research, the values of fresh leaf weight per plant were found to be statistically significant and higher values were obtained at 25x50 cm plant density. Fresh leaf weight per plant increased with the increase in the number of plants per unit area. The reason for this was that the number of plants per decare increased with plant density and the plants competed for access to sunlight, and the increase in plant height indirectly increased the fresh leaf weight per plant. This situation was observed in the first form and form averages. There was no statistical difference in the second form. The findings of the study were lower than the findings of Samadpourrigani (2014), Gedik and Tansı (2017) obtained from three and four year old plants.
Fresh leaf yield (kgha − 1 )
According to 2017 data, the highest fresh leaf yield average was determined at the second harvest time with 1398.6 kgha− 1 and the lowest fresh leaf yield average was determined at the first harvest time with 1358.6 kgha− 1.
Table 9
Mean Values and Resulting Groups of Fresh Leaf Yield of Stevia at Different Plant Densities and Different Harvest Times
|
Fresh Leaf Yield (kgha− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
1926.8 a
|
1726.6 b
|
1826.7 A
|
2262.0 a
|
1940.0 b
|
2101.0 A
|
30x50 cm
|
1463.7 c
|
1438.9 c
|
1451.3 B
|
1784.4 c
|
1525.0 d
|
1654.7 B
|
35x50 cm
|
1212.8 de
|
1280.0 d
|
1246.4 C
|
1533.4 d
|
1245.0 f
|
1389.4 C
|
40x50 cm
|
831.2 f
|
1148.9 e
|
990.0 D
|
1375.9 e
|
1255.0 f
|
1315.5 D
|
Averages
|
1358.6
|
1398.6
|
|
1739.0 A
|
1491.3 B
|
|
LSD (0,05)
|
Harvest time (ns), Plant density** (757), Interaction** (1070)
|
Harvest time* (60.3), Plant density* (73.1), Interaction* (103.3)
|
The highest fresh leaf yield average was 1826.7 kgha− 1 at 25x50 cm plant density and the lowest fresh leaf yield average was 990.0 kgha− 1 at 40x50 cm plant density. According to harvest time x plant density interaction, the highest fresh leaf yield was obtained 1926.8 kgha− 1 at 25x50 cm plant density in the first harvest period and the lowest fresh leaf yield was obtained 831.2 kgha− 1 at 40x50 cm plant density in the first harvest period. As a result of the research, the highest fresh leaf yield was obtained at 25x50 cm plant density in the first harvest period, while the lowest fresh leaf yield was obtained at 40x50 cm plant density. As the plant density increased in the first harvest period, it was determined that fresh leaf yield increased. In the second harvest period, the highest fresh leaf yield was recorded at 25x50 cm plant density, while the lowest fresh leaf yield was recorded at 40x50 cm plant density. When the second year data are analysed, it is seen that similar results were obtained with the first year data even if the figures changed. As a result of the research, fresh leaf yield values were found to be statistically significant and it was observed that fresh leaf yield values increased as the plant density increased. Although the difference between harvest times in the first year was found insignificant, the first harvest time in the second year was statistically higher (Table 9). The data obtained are in harmony with the fresh leaf weight per plant. It is thought that this situation is due to the fact that the second harvest period coincides with short days and the plant encourages the generative parts rather than the vegetative parts. The findings obtained in this study are lower than the findings of Ruta et al. (1999), Taleie et al. (2012), Samadpourrigani (2014), Tadesse et al. (2016) Gedik and Tansı (2017) obtained from 3 and 4 old plants.
Dry Branch Yield (kgha − 1 )
According to 2017 data, the highest fresh branch yield average per plant was determined at the second harvest time with 655.6 kgha− 1 and the lowest fresh branch yield average was determined at the first harvest time with 202.9 kgha− 1. The highest average dry branch yield was 482.5 kgha− 1 at 30x50 cm plant density and the lowest average dry branch yield was 366.7 kgha− 1 at 40x50 cm plant density. According to harvest time x plant density interaction, the highest dry branch yield was obtained 748.5 kgha− 1 at 30x50 cm plant density in the second harvest period and the lowest dry branch yield was obtained 126.8 kgha− 1 at 40x50 cm plant density in the first harvest period.
Table 10
Mean Values of Dry Branch Yield of Stevia at Different Plant Density and Different Harvest Times and Resulting Groups
|
Dry Branch Yield (kgha− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
263.4 c
|
640.0 b
|
451.7 B
|
460.5 b
|
845.5 a
|
653.0 A
|
30x50 cm
|
216.5 d
|
748.5 a
|
482.5 A
|
352.3 c
|
562.0 b
|
446.1 B
|
35x50 cm
|
204.9 d
|
627.5 b
|
416.2 C
|
277.5 cd
|
540.0 b
|
419.8 BC
|
40x50 cm
|
126.8 e
|
606.7 b
|
366.7 D
|
219.4 d
|
474.0 b
|
346.7 C
|
Averages
|
202.9 B
|
655.6 A
|
|
327.4 B
|
605.4 A
|
|
LSD (0,05)
|
Harvest time** (30.0), Plant density** (24.3), Interaction** (34.4)
|
Harvest time* (52.3), Plant density* (75.8), Interaction (ns)
|
In the first harvest period, it was determined that dry branch yield increased as the plant density increased and the harvest time was delayed. In the second harvest period, the highest dry branch yield was recorded at 30x50 cm plant density, while the lowest dry branch yield was recorded at 40x50 cm plant density. When the second year data were analysed, it was observed that there was a positive relationship between plant density and dry twig yield increase, which was similar to the first year data. The highest values were obtained from 25 x 50 cm row spacing application in terms of both first harvest time, second harvest time and harvest time averages (Table 10). As a result of the research, dry branch yield values were found to be statistically significant and dry branch yield increased with the increase in the number of plants per unit area. This is thought to be due to the increase in plant density and number of plants per decare. The increase in fresh branch yield at the second harvest time is due to the fact that as the vegetation period of the plant is prolonged, more nutrients are formed in the stem of the plant, hardening and carding of the stem, and fresh branch yield per plant was obtained more in the second harvest. As a result of the study, as the plant density increased, the number of plants per unit area increased and fresh branch yield increased, and more dry branch yield was obtained in the second harvest due to stem hardening and carding. The findings of the study were lower than the findings of Valois (2002), Tulasi (2006), Samadpourrigani (2014), Gedik and Tansı (2017) for three and four year old plants, and parallel to the findings of Kumar et al. (2013).
Dry leaf weight per plant (g plant − 1 )
According to 2017 data, the highest average dry leaf weight per plant was determined at the second harvest time with 6.33 g plant− 1 and the lowest average dry leaf weight per plant was determined at the first harvest time with 5.93 g plant− 1. The highest average dry leaf weight per plant was 6.85 g plant− 1 at 25x50 cm plant density and the lowest average dry leaf weight per plant was 5.17 g plant− 1 at 40x50 cm plant density.
Table 11
Mean Values of Dry Leaf Weight Per Plant of Stevia at Different Plant Densities and Different Harvest Times and Resulting Groups
|
Dry Leaf Weight Per Plant (g plant− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
7.17 a
|
6.34 cd
|
6.75 A
|
10.37 b
|
11.79 a
|
11.08 A
|
30x50 cm
|
6.63 bc
|
7.08 ab
|
6.85 A
|
9.40 bc
|
9.81 bc
|
9.61 B
|
35x50 cm
|
5.50 e
|
5.97 de
|
5.73 B
|
8.94 cd
|
8.63 cd
|
8.78 BC
|
40x50 cm
|
4.42 f
|
5.92 de
|
5.17 C
|
8.82 cd
|
7.94 d
|
8.38 C
|
Averages
|
5.93 B
|
6.33 A
|
|
9.38
|
9.54
|
|
LSD (0,05)
|
Harvest time** (0.28), Plant density** (0.37), Interaction** (0.52)
|
Harvest time (ns), Plant density* (0.85), Interaction (ns)
|
According to harvest time x plant density interaction, the highest dry leaf weight per plant was obtained at 25x50 cm plant density in the first harvest period and the lowest dry leaf weight per plant was obtained at 40x50 cm plant density in the first harvest period and 4.42 g plant− 1. As a result of the research, the highest dry leaf weight per plant was obtained at 25x50 cm plant frequency in the first harvest period, while the lowest dry leaf weight per plant was obtained at 40x50 cm plant frequency. In the second harvest period, the highest dry leaf weight per plant occurred at 30x50 cm plant density and the lowest dry leaf weight per plant occurred at 40x50 cm plant density. When the results obtained in the second year were analysed, it increased regularly as the plant population increased, just like the results obtained in the first year. In the first year, the mean harvest average was statistically significant, while it was insignificant in the second year (Table 11). As a result of the research, it is thought that the high plant density is due to the competition of plants for access to sunlight. The findings are in parallel with the fresh leaf weight per plant. It is thought that more dry leaf weight per plant was obtained in the second harvest. This is thought to be due to the increase in dry leaf weight per plant due to the increase in plant height and number of branches as the harvest time is delayed. The findings of the study were lower than the findings of Samadpourrigani (2014), Gedik and Tansı (2017) obtained from 3 and 4 year old plants.
Dry leaf yield (kgha − 1 )
According to 2017 data, the highest average dry leaf yield was determined at the second harvest time with 413.1 kgha− 1 and the lowest average dry leaf yield was determined at the first harvest time with 395.2 kgha− 1. The highest average dry leaf yield was 540.1 kgha− 1 at 25x50 cm plant density and the lowest average dry leaf yield was 275.6 kgha− 1 at 40x50 cm plant density. According to harvest time x plant density interactions, the highest dry leaf yield was 573.4 kgha− 1 at 25x50 cm plant density in the first harvest period and the lowest dry leaf yield was 235.6 kgha− 1 at 40x50 cm plant density in the first harvest period.
Table 12
Mean Values of Dry Leaf Yield of Stevia at Different Plant Density and Different Harvest Times and Resulting Groups
|
Dry Leaf Yield (kgha− 1)
|
|
2017
|
2018
|
Plant density
|
Harvest 1
|
Harvest 2
|
Averages
|
Harvest 1
|
Harvest 2
|
Averages
|
25x50 cm
|
573.4 a
|
506.8 b
|
540.1 A
|
829.5 b
|
943.0 a
|
886.3 A
|
30x50 cm
|
441.6 c
|
472.1 bc
|
456.9 B
|
626.6 cd
|
785.0 b
|
705.8 B
|
35x50 cm
|
330.0 de
|
358.1 d
|
344.0 C
|
536.3 de
|
690.0 c
|
613.1 C
|
40x50 cm
|
235.6 f
|
315.6 e
|
275.6 D
|
470.3 e
|
635.0 c
|
552.7 C
|
Averages
|
395.2 B
|
413.1 A
|
|
615.7 B
|
763.3 A
|
|
LSD (0,05)
|
Harvest time** (14.8), Plant density** (24.8), Interaction** (35.0)
|
Harvest time* (77.1), Plant density* (65.4), Interaction (ns)
|
In the first harvest period, the highest dry leaf yield was recorded at 25x50 cm plant density, while the lowest dry leaf yield was recorded at 40x50 cm plant density. In the first harvest period, as the plant density increased, dry leaf yield increased. In the second harvest period, the highest dry leaf yield was recorded at 25x50 cm plant density, while the lowest dry leaf yield was recorded at 40x50 cm plant density. When the data obtained in the second year of the research were analysed, it was found that the values obtained decreased as the plant population decreased and increased as the dry leaf yield values increased, showing a very close parallelism with the data obtained in the first year. The same situation was similar for the first and second harvest averages and the second harvest averages were higher than the first year averages (Table 12). As a result of the research, dry leaf yield values were found to be statistically significant and it was observed that dry leaf yield values increased as the plant density increased. It is thought that the reason why the increase in dry leaf yield in the second harvest is higher than the first harvest is that more nutrients are formed in the leaves and branches of the plant, and more dry leaf yield is obtained in the second harvest due to hardening and carding in the leaves and stems. It is thought that this situation is due to the fact that more nutrients are formed in the plant as the plant density and harvest time is delayed, especially fresh leaf yield is related to the number of branches and plant height (Midmore and Rank 2002), and the increase in fresh leaf yield causes an increase in dry leaf yield. The findings of this study are lower than the dry leaf yield findings of Brandle and Rosa (1992), Klienle (1993), Shyu (1994), Kornienko (1995), Megeji et al. (2005), Tulasi (2006), Burling (2007), Lankes and Pude (2008), Taleie et al. (2012), Samadpourrigani (2014), Tadesse et al. (2016) and in parallel with the findings of Kumar et al. (2013).