3. Results and Discussion
3.2. Field experiment results
Plant Height and Dry Weight: The results of the statistical analysis show that plant height at the age of 45 dap was not affected by the fertilization treatment tested, but the dry weight of the plants at the age of 30 dap and at harvest was significantly affected by the treatment given (Table 3). The effect of treatment on plant height that has not been seen was probably due to the fact that the treatment given has not been able to bring out the role of nutrients given through main fertilization of elements of N, P, K, and S or other growth factors that still allowed plants to grow to the height that has been expressed by individual plants.
Table 3: Plant height and dry weight of shallot plants in various treatments given.
Treatment
Plant Height
of 45 dap (cm)
Dry Weight of
30 dap (g/clump)
Dry weight at
harvest (g/clump)
Without Fertilizer Application (P0)
Standard Fertilizers Application and without Sulfur (P1) Standard Fertilizers Application and Sulfur (P2)
Sulfur Application without Standard Fertilizers (P3)
19.28 20.02 21.09 19.36
0.287a 0.332a 0.450b 0.549b
2.557a 4.282ab
6.659b 4.180ab Note: The numbers in the same column followed by the same letters are not significantly different in the HSD 0.05 test
The treatment of standard fertilization and sulfur (P2) resulted in producing the highest plant dry weight at harvest and was significantly different from the treatment without fertilization (P0), but not significantly different from other treatments (P1 and P3).
These data also show that the application of standard fertilizers alone (P1) could increase dry weight at harvest by 67.5%, and the addition of bio-sulfur fertilizers could increase dry weight by 55% than what would have been achieved if only standard fertilizers were used.
This means that the role of the elements nitrogen, phosphorus, and potassium increased plant dry weight when sulfur was added [14, 16-18]. Sulfur has both assimilation and metabolic functions because it is a constituent component of amino acids in plant tissue, such as cysteine and methionine as well as protein, where both amino acids are precursors for other compounds containing S such as coenzymes [2, 3]. Furthermore, it is said that the S distribution in sulfur-deficient plants can affect nitrogen supply so that protein formation will also decrease. The further effect on the formation of other complex compounds indicated on the formation of the dry matter is reduced.
Number of tillers, fresh weight, and tuber production: The data on the average number of tillers, tuber fresh weight, and tuber production are presented in Table 4. The experimental result shows that the treatment given did not have a significant effect on the number of tillers, but had an effect on the tuber fresh weight and the tuber production. The absence of treatment effect on the number of tillers was thought to be caused by a more dominant genetic factor so that it did not have a significant effect.
Table 4: Average of shallot tuber fresh weight in the field experiment (g/clump).
Treatment
Numb er of tillers
Tuber fresh weight (g/clump)
Tuber production
(kw/ha)
Without Fertilizer Application (P0)
Standard Fertilizers Application and without Sulfur (P1) Standard Fertilizers Application and Sulfur (P2)
Sulfur Application without Standard Fertilizers (P3)
8.901 10.021 10.563 9.479
8.708a 13.953ab
18.970b 10.725a
23.55a 43.51b 44.31b 34.21ab Note: The numbers in the same column followed by the same letter do not differ significantly according to the HSD test at the 5% level.
Table 4 shows that the highest average of shallot tuber fresh weight was obtained from treatment of standard fertilization and sulfur (P2) which differed significantly from the treatment without fertilizers application (P0) and sulfur application without standard fertilizer (P3), but not significantly different from the treatment of standard fertilizers application without sulfur (P1). The application of standard fertilizers without sulfur (P1) was able to increase the tuber fresh weight by 60% compared to without fertilizer application (P0). If the standard fertilizer was added with sulfur fertilizer (P2), it could increase the tuber fresh weight by more than two times compared to without fertilizer (P0) or increase the tuber fresh weight by 36% compared to only applied standard fertilizers (P1). This gives an indication of the role of sulfur which is additive as long as other nutrient conditions such as N, P, and K are sufficient [14] because in principle the absorption level of an element is also determined by other nutrient conditions which will be a limiting factor in adding tuber fresh weight.
Tuber production data per-hectare was obtained from the conversion of the observed result data of plant production per plot. The results of the HSD test showed that the highest average production of shallot tubers was obtained from the treatment of standard fertilization and sulfur (P2) which were significantly different from the treatment without fertilizer application (P0), but did not differ significantly compared to the treatment of standard fertilizer application without sulfur (P1 ) and sulfur application without standard fertilizers (P3). The application of standard fertilizers without sulfur (P1) could increase the production of shallot tuber by about 85% compared to without fertilizer application (P0). If standard fertilizers were added with sulfur fertilizer (P2), it could add the production increase by 88% compared to without fertilizer (P0) or increase the tuber fresh weight by 3% compared to only applied standard fertilizer (P1). This gives an indication of the role of sulfur in synergy with other nutrient conditions such as N, P, and K in the soil [19]. Low S content can inhibit protein synthesis which is correlated with the accumulation of dissolved N-organic and nitrates [2]. The rate of mineralization of organic N to inorganic N is an important factor in determining the availability of N in the soil. The inorganic N forms are ammonium (NH4 +) and nitrate (NO3–), the N2 and NO forms are the forms that are lost as gases due to the denitrification process. Of all the nutrients, N
elemental is needed in the greatest amount in tuber production and plants absorb nitrogen in the form of ammonium and nitrate [20].
Percentage of Tuber Size (Tuber Grade): The results of calculating the percentage of tuber size in the field experiment based on the grade have been briefly presented in Table 5. All treatments tried did not produce tuber sizes with large categories (weight > 5.0 g / tuber). The distribution of tuber sizes showed that the treatment of standard fertilizer application and sulfur (P2) resulted in a higher percentage of the number of tubers in the medium category compared to other treatments.
Table 5: Percentage of tuber size (tuber grade) in field experiment.
Treatment Size Category
Small Medium Without Fertilizer Application (P0)
Standard Fertilizers Application and without Sulfur (P1) Standard Fertilizers Application and Sulfur (P2)
Sulfur Application without Standard Fertilizers (P3)
97.92 53.13 32.29 43.75
2.09 46.88 67.71 56.25
Based on these data, it could be explained that relatively in accordance with the description of the planted shallot varieties had medium tuber size characters, with a yield potential of only 7 to 10 tons/ha. Therefore, a large tuber size was not obtained (> 5.0 g / tuber). However, the tuber size varied according to treatment. Treatment of standard fertilizer application (N, P, K, and organic fertilizers) and sulfur produced the maximum tuber size, namely 32.29% of small size and 67.71% of medium size. This size is related to the assimilated mass accumulated as a result of plant physiological activities, including metabolism that takes place in cells. Therefore, it can be said that each addition or application of nutrients through the given treatment results in an increase in the mass of the assimilate. This is of course driven by the role of each nutrient given. It is possible that the soil which became the planting media had a poor status of nutrients, especially N, P, K including the content of organic materials and sulfur, so that with each application of these nutrients, the plant responded through an increase in cell size and mass which was then shown in tuber weight.