Growth of Samosir Local Shallots Due To The Types and Dosage of Trichoderma Spp Isolate

. Trichoderma spp fungus can be used as a biostimulant for plant agronomic characters. This study was aimed to determine the eﬀect of Trichoderma spp isolate, dosage, and interaction on the growth of Samosir shallots. This study was carried out in Muara Subdistrict, North Tapanuli District, North Sumatra, Indonesia, from June to December 2021. This study used a factorial randomized block design with three replications, the ﬁrst factor being the types of Trichoderma spp (T. harzianum, T. virens, T. viride, T. asperellum). The dosage of Trichoderma spp such as 0; 20; 40; and 60 g/polybag was the second factor. Parameters were processed using ANOVA followed by DMRT at P<0.05. The ﬁndings revealed that the higher ability of T. viride isolates to increase the plant height growth of Samosir shallots. The dose higher of isolated up to 60 g/polybag increased the plant height and number of leaves in Samosir shallots. The interaction of T. asperellum isolate at a dose of 20 g/polybag showed the highest number of leaves compared to other interactions.


Introduction
Shallot (Allium cepa L.) is one of the world's most popular vegetables, and its economic value has a significant impact on both domestic and international markets [1].In 2021, the seven provinces in Indonesia with the highest shallot yield are Central Java, East Java, West Nusa Tenggara, West Sumatra, South Sulawesi, West Java, and North Sumatra.The seven provinces contributed 94.59% of the total shallot yield (2,004,590 tons) in Indonesia and North Sumatra Province contributed 2.69% [2,3] reported that North Tapanuli is the 6th highest district of shallot yield central in North Sumatra after Simalungun, Humbang Hasundutan, Karo, Dairi, and Samosir Districts.The production of shallots from the six districts must be increased annually to satisfy domestic needs and support exports to several countries.
The local variety that is intensely used by the farmers in North Tapanuli District namely Samosir shallots.The habit of farmers in cultivating Samosir shallots is also often using chemical fertilizers.The application of chemical fertilizers in an excessive and sustainable manner will have an impact on shallot yield and quality due to decreasing soil fertility, and can even interfere with human health and harm the environment.According to [4] the usage of bio-fertilizers is an alternative to enhancing yield while causing minimal environmental damage.
Trichoderma, a biofertilizer, is an excellent biocontrol agent, stimulating plant growth, enhancing plant resistance, and increasing soil fertility.It has been reported by [5] inoculation of T. harzianum on shallot seedlings can increase growth and yield.[6] added that Trichoderma also promoted plant development by secreting indole acetic acid (IAA), enhancing nutrient uptake, and optimizing fertilizer use.[7] also added that the application of Trichoderma spp at 20 ml/plant significantly increased the weight of the shallot bulbs.[8] found that the T. viride significantly increased the diameter and leaf area of shallot bulbs.[9] also found that T. harzianum and T. virens significantly increased the root length of shallot seedlings by 34.89 and 5.89% compared to the control.In contrast, the root length of shallots due to T. asperellum was lower than the control and both Trichoderma.
The slight information on the use of several doses and types of Trichoderma fungi on the local variety of Samosir shallots, that it is necessary to research several types of useful Trichoderma.This study was to determine the effect of Trichoderma spp isolates (T.harzianum, T. virens, T. viride, T. asperellum), dosage, and their interactions on the agronomic characters of Samosir shallot.

Design and study field
This study was conducted at an altitude of 1,000 m asl in Dolok Martumbur Village, Muara Subdistrict, North Tapanuli District, North Sumatra, Indonesia from June to December 2021.Propagation of Trichoderma spp.isolates conducted at the laboratory of the Department of Agriculture in North Tapanuli.This study used a factorial randomized block design with three replications, the first factor was the types of Trichoderma spp.(T.harzianum, T. virens, T. viride, T. asperellum).The second factor was the Trichoderma dosage (0; 20; 40; 60 g/polybag).

Selection of shallot bulbs and growing medium
Shallot bulbs were collected from Baktiraja Village, Bakkara Subdistrict, Humbang Hasundutan District.Selected one bulb of shallot was homogeneous in size, and healthy, the skin surface was glossy, and the bulb's skin was not peeled.This study using a vaiety of Samosir shallot and planted two bulbs in the polybag.The growing medium used a mixture of soil, dolomite, and poultry manure at a dose of 10 tons ha -1 .The mixture was stirred and then put into polybags with a diameter of 40 cm and a height of 25 cm.The planting medium was incubated and applied of SP-36 fertilizer with a dose of 5 g/polybag at three days before planting.

Source and application of trichoderma spp.
Trichoderma spp.isolates were taken from the Pest and Disease Laboratory, Faculty of Agriculture, Universitas Sumatera Utara, Indonesia.The isolates were cultured on boiled maize media.Isolates that successfully grew were marked with green color and fragrant then applied to polybags according to the treatment.Trichoderma spp.isolates were spread and flattened from the soil surface before the bulbs were planted into polybags.

Growing of shallot bulbs and data analysis
Growing media was watered one day before planting.Bulbs are planted in polybags with two bulbs per polybag.Fertilization was carried out three times (at planting; 2; and 4 weeks after planting/WAP) with NPK 15-15-15 at one ton ha -1 and then applied to the justify side of the plant.Watering is carried out daily depending on field conditions, and weed control was carried out manually.Parameters measured in this study included plant height, number of leaves, and number of flowers.Measurement of plant height and number of leaves were conducted at 76 days after planting (DAP) while the number of flowers at 83 DAP.Parameters were processed using an ANOVA then continued with the DMRT at P<0.05.

Result
Types and doses of Trichoderma spp.isolates significantly increased the plant height of the Samosir shallots, but their interaction had an insignificant effect (Figure 1 and Table 1).The findings revealed that the isolates of T. viride (T3) and T. asperellum (T4) had a similar ability to increase the plant height of Samosir shallots.The highest plant height was found in the T. viride isolate at 57.65 cm.Other results also showed that the higher the isolate dose up to 60 g/polybag resulted in an increase in plant height of Samosir shallot by 6.51% compared to the untreated.Although the effect was insignificant, the interaction of T. virens at a dose of 60 g/polybag (T2D3) showed the highest plant height of Samosir shallot by 60.44 cm compared to other interactions.
The dose of Trichoderma spp isolates and their interaction significantly increased the number of leaves in Samosir shallots, but the types of isolate had an insignificant effect (Figure 2 and Table 1).The findings revealed that the higher dose of isolates up to 60 g/polybag increased the number of leaves in Samosir shallots by 9.33% compared to the untreated.The interaction of T. asperellum isolate at 20 g/polybag (T4D1) showed the highest number of leaves in Samosir shallot compared to other interactions.Although the effect was insignificant, T. viride isolate (T3) showed the highest number of leaves in Samosir shallot by 67.53 compared to other isolates.Types, dosage of Trichoderma spp.isolates and their interactions had an insignificant effect on the number of flowers in Samosir shallots (Figure 3 and Table 1).The results showed that the highest number of flowers in Samosir shallots was found in T. asperellum isolate (T4), a dose of 40 g/polybag, and the interaction of T. virens at 20 g/polybag (T2D1) compared to other treatments, although the effect was insignificant.

Discussion
Types of Trichoderma spp.isolates only significantly increased the plant height of the Samosir shallots, but it had a fewer impact on the number of leaves and flowers.T. viride isolate had the highest impact on increasing the plant height of the Samosir shallots by 57.65 cm compared to other isolates.It was caused by Trichoderma spp.isolates had positive effects on plant growth such as increasing nutrient availability and producing phytohormones, and it has an impact on increasing the plant height of the Samosir shallot.This finding was supported by [10] that Trichoderma sp. could be classified as growth-promoting fungi by increasing the nutrient availability (Fe, N, P) and producing phytohormones for plants.[11] also added that Trichoderma sp. can produce antibiotics such as polyketides, trichodermin, peptaibols, trichodermol, and steroids that promote plant growth.[8] reported that the T. viride significantly increased plant height, chlorophyll content (a, b, total), carotenoids, and total pigment of shallot plants.
Dosage of Trichoderma spp.isolates considerably enhanced plant height and leaf number in Samosir shallot, but had less of an effect on flowers number.The higher the dose of isolate up to 60 g/polybag resulted in the greater the effect on the plant height and leaf number in Samosir shallots.The growth of plant height and the number of leaves in Samosir shallot due to the dose of 60 g/polybag were 6.51 and 9.33%, respectively, compared to the untreated.It was caused by the higher dose of isolates affecting the population of Trichoderma spp.increase the ability of the isolates in producing phytohormones, nutrient availability, and producing antibiotics that encourage the growth of shallot plants.This finding was supported by [7] that the higher the dose of the Trichoderma spp. up to 20 ml/plant resulted in the higher growth of shallot plant height (41 cm) at 35 days after application (DAA).[12] also reported that the higher the dose of Trichoderma spp. up to 20 ml/polybag resulted in a higher number of leaves in shallot (24 leaves) at 28 DAA.[5] added that the T. harzianum also increased plant height, the number of leaves, leaf area, and chlorophyll content of shallot plants by 8.74, 7.86, 16.67, and 5.60%, respectively, as compared to the untreated.
Interaction of types and doses of Trichoderma spp.isolates significantly increased the number of leaves in Samosir shallots.However, it had minimal influence on plant height and the number of flowers.The interaction of T. asperellum isolate at the dose of 20 g/polybag indicated the highest leaf number in Samosir shallots compared to other interactions.It was caused by the interaction of T4-20 that could increase the physiological and biochemical processes of the Samosir shallots and it had an impact on increasing the number of leaves.It was seen from the number of leaves in Samosir shallots from T. asperellum (T4) isolate were insignificantly different from other isolates (Figure 2A), but at dose from 20 to 60 g/polybag revealed a significant difference in the leaf number than to the untreated (Figure 2B).This finding was supported by [13] that T. asperellum T42 can promote plant growth due to increasing chlorophyll, carotenoids, total carbohydrates, and protein content compared to the control.[14] also reported that T. asperellum T42 can increase root hairs, lateral roots, and root biomass.
This root development has an impact on the number of nutrients absorbed and refers to the development of the plant shoots such as the number of leaves.This study indicates that both isolates (T.viride and T. asperellum) at the dose of 20 g/polybag could be recommended to farmers to support sustainable agriculture, be eco-friendly, and save production costs.

Conclusions
T. viride isolate and a dose of 20-60 g/polybag could be increased the growth of the Samosir shallots.However, the interactions of T. asperellum at 20 g/polybag produced the most leaves.The selection of T. viride and T. asperellum isolates at the dose of 20 g/polybag can be recommended to farmers.

Table 1 .
Effect of interaction between types and dosage of Trichoderma spp.isolates on plant height, number of leaves, and number of flowers of the Samosir shallots.