Increasing the quantity and quality of potatoes by utilizing seed size and fish organic fertilizer

. Potato plants are one of the vegetables that are in great demand by consumers so they have high economic value and needs. The fulfillment of high needs must be accompanied by increased productivity. Increased potato production can be done, among others, by the use of seeds and proper fertilization. This study aims to determine the use of seed size and addition of fish organic fertilizer with inorganic fertilizer efficiency in increasing potato growth and yield. The study is carried out from June until September 2019 in research and assessment installation of agricultural technology, Dolat Rayat District, Karo Regency. The research placed altitude is ± 1,340 m above sea level, and the soil type is Andisol. The research design is a factorial randomized block and consists of three replications. The first-factor treatment is seed size (big >20 g, medium 5-20 g, small <5 g). The second factor is a fish organic fertilizer with efficiency inorganic fertilizer (100% inorganic fertilizer, 50% fish organic fertilizer + 75% inorganic fertilizer, 100% fish organic fertilizer + 50% inorganic fertilizer, and 150% fish organic fertilizer + 25% inorganic fertilizer). The result showed that big and medium seed sizes were able to increase potato growth and yield. Big and medium seed sizes were able to increase plant height by 11.06% and 9.63%, 5,73%, and 4,64% canopy width, 7.30%, and 11.10% leaf area index, and 12.62% and 25.06% yields from small seed size. Adding fish fertilizer with inorganic fertilizer efficiency resulted in growth and yield which is no different from the application of 100% inorganic fertilizer.


Introduction
Potato (Solanum tuberosum) is a short-lived vegetable crop which has wide adaptability in the highlands and used as a source of carbohydrates for many people in tropical and subtropical regions [1].The tubers are widely consumed by the community as vegetables so they play an essential role in the Indonesian economy and currently its need is increasing in the market.The need for potatoes continues to increase due to population growth and changes in consumption patterns in several developing countries.Potato plants are pretty strategic in providing food to support food security.The increase in consumer demand of must be accompanied by an increase in productivity.Increased productivity of horticultural crops is strongly influenced by quality seed, planting materials, and soil fertility [2].
Globally, potato is the third most important food crop in terms of consumption after rice and wheat [3,4].In Indonesia potato productivity in 2020-2021 is reach 19.55 tons ha -1 to 18,74 tons ha -1 [5].Based on these data, the productivity of potato plants in national still low, because according to agriculture ministry potato productivity can reach 20-25 tons ha -1 .However proper cultivation management is needed to increase potato production.Increasing vegetable productivity can be done by handling the right cultivation, including the use of appropriate seeds and fertilization.
Potatoes can be classified based on their weight, namely big, medium and small, where farmers usually use potatoes as seeds of medium and small size.The size of the tuber greatly affects the vigor of the growing plant.According to Sadik et al [6], using any of large (46-55 mm) or medium (35-45 mm) seed tuber sizes resulted in the highest total tuber yield of potato.
The results of research [7] on onion plants also showed that big seed sizes produced higher yields than medium and small sizes.
Farming of cultivation requires fertilization management to be applied to maximize the nutrient content in fertilizers [8].Utilization of organic matter in organic farming practices has shown beneficial effects by increasing soil organic matter content, soil porosity, structural stability, moisture, nutrient availability, biological activity, and reducing soil erosion [9].Fish fertilizer is one of the organic fertilizers derived from fish waste.The study's results [10] stated that fish waste could be used as compost for soil improvement which is suitable for horticultural crops grown by organic methods.The use of fish organic fertilizer for plants has been widely studied, including research results [11] showing that the application of fish fertilizer 1000 kg ha -1 can increase the weight/plant, production/plot, and the percentage of big grade in potato plants.The use of the right size of fish seeds and organic fertilizer is expected to increase the growth and production of potatoes and reduce the use of inorganic fertilizers.
This research aims to determine the use of seed size and the addition of fish organic fertilizer with inorganic fertilizer efficiency to increase potato growth and yield.

Material and methods
The study is conducted from June until September 2019 in research and assessment installation of agricultural technology, Dolat Rayat District, Karo Regency.The research placed altitude is ± 1,340 m above sea level, and the soil type is Andisol.The research design is a factorial randomized block and consists of three replications.The first-factor treatment is seed size (big >20 g, medium 5-20 g, small <5 g).The second factor is a fish organic fertilizer with efficiency inorganic fertilizer (100% inorganic fertilizer, 50% fish organic fertilizer + 75% inorganic fertilizer, 100% fish organic fertilizer + 50% inorganic fertilizer, and 150% fish organic fertilizer + 25% inorganic fertilizer).

Procedure
The land was processed and cleaned, then made the trial plot with a size of 1.5 m x 2 m, with a bed size of 1.2 m x 2 m.The space among treatments is 1 m and the range among replicates is 2 m.Then given manure with a dose of 2 kg m-2 and chemical fertilizer NPK 16-16-16 80 g plant-1.The fish organic fertilizer for potatoes is 1000 kg ha -1 [11] and given according to the tested treatment before planting.Chemical fertilizers are given 1 time, which is given by spreading on the bed and then covering with soil to a height of 30 cm and covering with mulch.Three days after the application of fertilizer, potato seedlings are planted and covered with soil.Planting tubers in the bed is done in 2 rows, with a spacing of 60 cm x 40 cm.
Maintenance is weeding and controlling pest and disease attacks with insecticide active ingredients profenofos, cypermethrin 50 g L -1 at a dose of 2 cc L -1 water, chlorantranilipol 50 g L -1 , emamectin benzoate at a dose of 0.5-1.0cc L -1 water, imidacloprid, summit at a dose of 1 cc L -1 water, and fungicide mancozeb or difenoconazole 250 g at a dose of 2 g L -1 water.Spraying is conducted one time for four days.Harvesting can be done when the plants are 90 days after planting.

Data analysis
The observation variables consisted of height and canopy width of plants at 3, 5, and 7 WAP, leaf area index, and yields.The average data were analyzed using the F-test and continued with the HSD test at a 5% level.

Plant height, canopy width and leaf area index
Based on the analysis of the variance of plant height, it showed that the seed size treatments had a significant effect on the growth of potatoes at 3, 5, and 7 weeks after planting.Treatments of fish organic fertilizer with inorganic efficiency had no significant effect (Table Table 1.Effect of seed size and fish organic fertilizer on plant height and canopy width at 3, 5 and 7 weeks after planted and leaf area index.Means followed by the same letter on the same columns is not significant different by HSD test at 5% level WAP = Week after plant FOF= Fish organic fertilizer IF = Inorganic fertilizer Differences in seed size resulted in different growth of potato plants, where big seed size (> 20 g) resulted in height and canopy width of plants aged 3, 5, and 7 WAP and leaf area index that was not significantly different from medium seed size (5-20 g). and significantly different with small seed size (<5 g).The highest plant height and canopy width were obtained from the use of big seeds, where there was an increase of 11.05% and 5.73% from the use of small seeds, respectively.Meanwhile, in the leaf area index, the highest was obtained at medium seeds size (28.94mm) which was not significantly different from big seed size (27.75 mm) and significantly different from small seed size.This is supported by research results [6,12] stated that big tuber seed size resulted in higher growth than small tuber seed size.

Treatments
The increase in plant growth is strongly influenced by the needs of plants as food, where if the needs of plants for food are fulfilled then plants can grow and develop properly.The size of the seed and the application of foliar fertilizers greatly affect the availability of food reserves and nutrient intake through the leaves.According to Purnawanto [13] this is characterized by endosperm which has a big size and is able to provide the energy needed by plants for growth thereby increasing the plant growth process.

Yield
Analysis of the average production yielded that the seed size treatment had a significant effect on medium tuber weight, small tuber weight, medium tuber number, number of small bulbs, and tuber weight per plot.The treatment of giving fish organic fertilizer with inorganic fertilizer efficiency gave a significant effect on the number of big tubers and tuber weight per plot (Table 4).The interaction of the two treatments had a significant effect on tuber weight per plant and big tuber weight (Tables 2 and 3).Means followed by the same letter on the same rows and columns is not significant different by HSD test at 5% level FOF= Fish organic fertilizer IF = Inorganic fertilizer The interaction of seed size and application of fish organic fertilizer with inorganic fertilizer efficiency gave a significant effect in producing the highest tuber weight per plant in the treatment of big seed size and 150% fish organic fertilizer + 25% inorganic fertilizer, namely 1.15 kg.In general, it was found that the use of medium-sized seeds (5-20 g) resulted in higher tuber weights.Likewise, the application of fish organic fertilizer with inorganic fertilizer efficiency resulted in higher tuber weight than the use of 100% inorganic fertilizer.Means followed by the same letter on the same rows and columns is not significant different by HSD test at 5% level FOF= Fish organic fertilizer IF = Inorganic fertilizer The of big tubers was influenced by the interaction of seed size and application of fish organic fertilizer with inorganic fertilizer efficiency, where the treatment of medium seed size and 100% fish organic fertilizer + 50% inorganic fertilizer resulted in the highest big tuber weight, which was 0.52 kg per plant and was not significantly different.with the use of big and small size seeds given 150% fish organic fertilizer + 25% inorganic fertilizer.Means followed by the same letter on the same columns is not significant different by HSD test at 5% level FOF= Fish organic fertilizer IF = Inorganic fertilizer Medium to big seed size resulted in weight and number of big and small tubers and tuber weight per plot which was significantly higher than the small seed size.In general, the highest weight and number of medium and small tubers was obtained at big seed size, while the highest tuber weight per plot was obtained at medium seeds size, which was 7.88 kg.This shows that seed size affects the yield of the plant, where medium-big size tubers are better than small seed size tubers.
The big size of the seed has a wide cross-section, so it is suspected that it will also produce more buds that will release roots so that later the roots play a role in nutrient absorption and the source of tuber formation.The results of the study [6], showed that there was a significant effect of big tuber size on fresh weight, tuber large size, and number of tubers.In addition, big and medium tuber sizes resulted in a more significant increase in yield than small tubers The application of fish organic fertilizer with inorganic fertilizer efficiency was able to produce higher tuber weight and tuber weight per plot than the use of 100% inorganic fertilizer.The use of 150% fish organic fertilizer and 25% inorganic fertilizer resulted in an increase in the weight of big tubers and tuber weight per plot by 20.76% and 15.74%, respectively, from the use of 100% inorganic fertilizer.This is suspected to be the role of organic fertilizers that can increase soil organic matter and nutrient availability, and also increase soil biological activity [14], so that the soil becomes better as a medium for growing plants which will later affect the yield.Accordance to the previously research result [15,16] that the application of organic fertilizers can increase the potato yield.In addition, the application of organic fertilizers can reduce inorganic fertilizers because the function of fertilizers can increase the effectiveness of inorganic fertilizers.According to research results [17,18], the application of liquid organic fertilizer has several benefits, including being able to reduce the use of chemical fertilizers.

Conclusion
The big and medium seed sizes were able to increase plant height by 11.06% and 9.63%, 5.73%, and 4.64% canopy width, 7.30%, and 11.10% leaf area index from small seed size.The big and medium seed sizes were able to increase the tuber weight per plant 20.06% and 23.27%, yield per plot 21.36% and 25.06% from small seed size.Adding fish fertilizer with inorganic fertilizer efficiency in growth and yield is higher than using 100% inorganic fertilizer.The use of 150% fish organic fertilizer and 25% inorganic fertilizer resulted in an increase in the weight of big tubers and tuber weight per plot by 20.76% and 15.74% from the use of 100% inorganic fertilizer.

Table 2 .
Effect of seed size and fish organic fertilizer on tuber weight per plant.

Table 3 .
Effect of seed size and fish organic fertilizer on big tuber weight.

Table 4 .
Effect of seed size and fish organic fertilizer on big, medium and small tuber.