Responses of shallot to ameliorant and actinobacteria applications in water-saturated system on tidal land

Tidal areas are believed as future land for many commodities in Indonesia. Here, shallot growing was evaluated on tidal land supplemented with soil conditioners. The research aimed to evaluate the adaptive response of shallot varieties for growing on tidal land with a water-saturated system indicating Fe and Al stress by applying soil ameliorant and actinobacterial. The study used a completely randomized factorial design with three replications. The first factor was shallot variety (Bima Brebes, Batu Ijo, and SS Sakato) and the second factor was soil conditioners (no ameliorant, actinobacteria, ameliorant+actinobacteria, and actinobacteria+ameliorant+dolomite). Bima Brebes and Batu Ijo cultivars had the highest growth percentage, age at shoot emergence, plant height, and number of leaves, while the SS Sakato variety had the slowest growth. Shallot production variable had a significant interaction with soil conditioners. Bima Brebes variety demonstrated high suitability for a water-saturated system in tidal land, and actinobacteria+ameliorant+dolomite was a more promising conditioner than other treatments.


INTRODUCTION
Shallot (Allium ascalonicum L) is an important commodity for Indonesians.The increase in shallot prices due to fluctuations in national production can cause economic inflation.Shallot productivity is around 9-10 tons ha -1 (Susanti & Supriyatna, 2020).Statistic Bureau (BPS, 2022) noted five provinces as shallot production centers in Indonesia, i.e., Central Java, East Java, West Nusa Tenggara, West Java, and West Sumatra contribute 91.90% of Indonesian production, and Central Java province contributes the highest.However, domestic supply is still shortage.
Tidal land can be used for new agricultural production, especially shallot.Utilization of tidal land, which is suboptimal land, is a viable alternative (Saputra & Sari, 2021).Tidal land in Indonesia is estimated at 20.12 million ha, around 16.19% of the total agricultural land in Indonesia which covers an area of 124.25 million ha, with details of potential land at 2.07 million ha, acid sulfate land 6.72 million ha, peat land at 10.89 million ha, and saline land 0.33 million ha, the area land that has the potential to be used as agricultural land reaches 8.536 million ha, of which 2.834 million ha have been reclaimed and 5.702 million ha have not been reclaimed (Sahuri et al., 2023).
Soil and water management are the primary keys to agricultural cultivation on tidal land.Water-saturated cultivation technology can reduce levels of oxidized pyrite (Ghulamahdi, 2017;Toyip et al., 2019).Providing ameliorants and actinobacteria, fertilizing, and adding macro and micronutrients to improve soil nutrient status and soil pH.Actinobacteria are nitrogen-fixing bacteria that can fix nitrogen from the air and convert it into a form that plants can absorb.This water-saturated cultivation system will eliminate the negative influence of excess water on plant growth.It will acclimatize for two weeks after planting.Then, the plant will improve its growth by allocating photosynthesis results to the bottom of the plant for root growth and root nodules for 2-4 weeks after implementation.Irrigation begins (Ghulamahdi et al., 2016).This system can suppress pyrite oxidation, prevent a decrease in pH, reduce Al and Fe, and increase nutrient availability (Sagala et al., 2018).
The shallot crop commodity also has the potential to be developed on tidal areas by using appropriate technology, one of which is the use of adaptive varieties and by applying the concept of water-saturated cultivation.The findings of the research (Haitami et al., 2023), show that the tolerant shallot variety is Bima Brebes with a water table depth of 20 cm.One method of planting shallots in tidal land with adequate irrigation can be done with a water-saturated cultivation system (WSCS), namely planting by providing ongoing irrigation and ensuring the water level remains constant for the layer below the roots to be saturated with water.
Research on shallots in tidal areas has been conducted by testing six varieties at various water level depths.After successfully researching shallots at different water table depths (Haitami et al., 2023) the weakness is that it is necessary to add ameliorant input, such as manure, dolomite, and actinobacteria are growth-promoting hormones and can chelate Fe in tidal fields (Retnowati et al., 2018).Therefore, it is required to implement the use of manure, dolomite, and actinobacterial ameliorant for shallot plants in tidal fields that are saturated with water so that it is hoped that they will be able to evaluate the growth response and yield of several varieties of shallots cultivated in tidal fields which are saturated with water.The research aimed to evaluate the adaptive response of shallot varieties for growing on tidal land with a water-saturated system indicating Fe and Al stress by applying soil ameliorant and actinobacterial.

Research design
The research was carried out in type B tidal fields in plastic houses in Mulyasari village, Tanjung Lago subdistrict, Banyuasin regency, South Sumatera province, from April to June 2023.Water level of type B tidal field was influenced by high tides.The soil was flooded by freshwater 50-100 cm for 3-6 months, soil pH of 3.5-4.5 (acid), had fairly thick layer of pyrite, moderate organic content (2-4%), low N and P contents, and medium K content.
This experiment used a completely randomized factorial design with the first factor of shallot variety and the second factor of ameliorant and actinobacteria (control [no ameliorant, no actinobacteria], actinobacteria, actinobacteria+ameliorant=AA, and actinobacteria+ ameliorant+ dolomite=AAD).In total, the experiment consisted of 12 treatment combinations with three replications or 36 experimental units.
The working formulation of actinobacteria was made of 1 L actinobacteria culture in production media plus 20% starter culture, then shaked and incubated at room temperature for 14 days.Sterile peat media was added as bacterial culture (2:1, m/m), and used as an inoculant.Shallot bulbs were treated with inoculant by soaking them in an actinobacterial media of 200 g kg -1 seed, according to treatments.

Fertilizer application
Shallot bulbs were planted in plastic polybags sized 30 cm in height.The polybag was placed in water and the water level was maintained at 20 cm in depth to coop with the water-saturated system.

Data analysis
Research data were analyzed using analysis of variance (ANOVA).Further DMRT test was carried out for any treatments that had a significant effect.All analysis was conducted using SAS 9.0 and Minitab software.

Soil and water qualities
The soil analysis before the experiment showed high organic matter content, very high P2O5, low K2O, pH H2O of 4.35, and a high exchangeable Al (Table 1).Cation exchange capacity values with high criteria and base saturation with low criteria.The water source for saturated water cultivation in this research originated from secondary drainage channels connecting to tidal water.Water quality during low and high tides is presented in Table 2.The electrical conductivity is not too high, namely, 0.630 dS m -1 at high tide and 0.546 dS m -1 at low tide, and it also has a low pH, namely 4.00 at high tide and 3.97 at low tide.

Actinobacterial inoculant content
Inoculants of actinobacterial contained macro and micronutrients (Table 3).The high organic C content in the inoculant could be due to the mixing effect with peat soil.Blanco-Canqui et al. (2013) stated that increasing organic C can increase soil aggregate stability, water storage capacity, water infiltration, biomass, soil microbial activity, and cation-anion exchange.Increasing organic C takes time (Hu et al., 2018) stated that providing organic fertilizer from crop residues increases C input by 0.9 Mg C/ha/year, and the average increase in C-organic over 4 years is 0.4 Mg C/ha /year.

Plant emergence
The variety influenced the percentage of growth and emergence of shoots (Table 4).The Bima Brebes variety had a higher percentage of growth and shoot emergence (P>0.05)than the Batu Ijo and SS Sakato varieties.The growth and shoot emergence of the Bima Brebes variety was higher when treated with Actinobacteria+Ameliorant+Dolomite.It is probable that the Bima Brebes variety is more adaptive to lowland tidal fields as compared to SS Sakato and Batu Ijo.According to Nabilah et al. (2023), the Sakato variety is more suitable for planting in the highlands with a production of about 27.62-29.44t ha-1.Varieties showed different abilities on bulb formation during the vegetative phase of 0-7 days after planting (DAP) and 14-21 DAP.
The shallot's variety and the application of actinobacteria significantly affected the growth percentage and the age at which shoots emerged.Shoot growth was influenced by varietal variations (Table 4).The fastest shoot growth was found in the Bima Brebes and Batu Ijo varieties, while the slowest was in the SS Sakato variety (P>0.05).All shallot varieties have pretty good growth patterns, but the growth of the SS Sakato variety is relatively slow compared to other varieties.

Plant height
Plant growth at ages 1, 2, 3, 4, and 5 WAP showed different responses between the varieties tested by providing ameliorant and actinobacteria in water-saturated cultivation in tidal fields (Table 5).The height of shallot plants at 1-5 WAP was significantly influenced by the application of AA and shallot varieties but not by their interaction.The average height of shallot plants given AAD was 32.03 cm, higher than the other treatments.Table 5 shows Bima Brebes variety had a higher plant height than the Batu Ijo and SS Sakato varieties.The Bima Brebes was more responsive by application of manure, dolomite, and AA.It is hypothesized that by applying water-saturated cultivation technology, Fe tends to be in a reductive situation and does not oxidize which may prevent from negative effect on plant growth.The application of AAD can significantly increase plant height and number of leaves.The interaction between plant height and treatments was not significant.It is speculated that the application of AAD can provide a nutrient supply for the growth of shallot plants, where in this study, the pH conditions were very acidic, and Fe and Al stress could result in the soil conditions becoming very acidic.The decrease in pH occurs due to the release of H + ions into the soil solution (Sagala et al., 2021).Note: Values followed by the same letter in the same column indicate nonsignificant differences according to DMRT at the level of 5%.
High Fe content can cause iron toxicity in plants and hamper the absorption of nutrients (Zhang et al., 2016).Thus, the application of actinobacterial-enriched ameliorant can increase the height of shallot plants because of the ability of actinobacterial-enriched manure ameliorant to increase soil moisture (Lazcano et al., 2021).An actinobacterial inoculant mixed with peat soil as an effective carrier (Kravets et al., 2021).
Table 6 shows that the addition of AAD increased the number of leaves significantly from 2 to 5 WAP being 26.87 pieces per plant.The Bima Brebes variety produced a large amount of leaves compared to the Batu Ijo and SS Sakato varieties.The number of leaves is very important to determine the growth and development of tubers.It is suspected that the application of AAD can increase nutrient levels, especially N, so the number of leaves is more significant with organic fertilization.Leaf formation requires optimal nitrogen nutrients, which play a role in the rate of photosynthesis and protein synthesis, thereby increasing the growth rate.Nitrogen plays a role in chlorophyll formation, so leaves appear greener (Biru, 2015).Organic fertilizer, especially manure, can increase the vegetative growth of shallots.Andishmand and Noori (2012) reported manure application improves fresh and dry weights in shallot.Manure treatment improves soil structure in favor of root growth.Note: Values followed by the same letter in the same column indicate nonsignificant differences according to DMRT at the level of 5%.
The application of AAD in combination with shallot varieties is prospective in tidal land, even though the research field conditions had a very acidic pH, and Al-dd and Fe stress were very high.Maintaining water-saturated cultivation with a water level of 20 cm is suitable for shallot production.In such a situation, roots of shallot plants might produce ethylene which stimulates the formation of aerenchyma tissue as a general adaptation mechanism of plants to anaerobic conditions.However, in the present experiment, the ethylene level and aerenchime tissue formation were not observed.The role of actinobacteria can produce siderophores and IAA and chelate Fe and Al (Retnowati et al., 2019;Alfiyah et al., 2021).

Tuber weight and number of tubers
Differences in tuber weight and number of tubers were significant between Bima Brebes and SS Sakato (Table 7).The application of AAD fertilizer increased the number of tubers.It seems that the application of AAD fertilizer has a more significant effect on the growth and development of shallot bulbs.In the control treatment without AAD, tubers had poor growth.It is probable that in control plants, excess Al and Fe stress might limit the plant growth.Pyrite formation could be available in control plants, although no symptom of pyrite poisoning was visible in the present experiment.Chaerunisa et al. (2021) noted that pyrite can cause a decrease in soil pH, and the application of ameliorant can increase plant tolerance to Fe and Al.

Interaction effect on shallot productivity
The application of AAD has a significant effect on shallot productivity (Figure 1).It is probably that ameliorant enriched with actinobacteria and dolomite increase humic acid, resulting in an increase in soil pH, activity of phosphate solubilizing bacteria, soil P availability, and a decreased solubility of Al and Fe (Ifansyah et al., 2013).The increase in shallot productivity also occurred due to manure application as organic material.However, in the present research, N status was low.According to Messele (2016), the growth of shallot is determined by the amount of N applied.In the present research, applying manure at 20 tons ha -1 and dolomite at a dose of 2 tons ha -1 seems suitable to ameliorate tidal land with a pH of 3.81-4.35.Provision of ameliorant is essential for crop productivity in tidal areas according to Kim et al. (2016).

CONCLUSIONS
Except for productivity parameters, the interaction between shallot varieties (Bima Brebes, Batu Ijo, and SS Sakato) and the provision of actinobacteria+ameliorant+dolomite (AAD) was not significant for all growth variables.The AAD treatment had the most significant effect, and the Bima Brebes variety was the most suitable and sound to be developed on tidal land with water-saturated cultivation.

Table 1 .
Soil analysis before the experiment and its status.

Table 2 .
Water quality during high and low tides.
Note: Analysis results at the AGH IPB Laboratory 2023.

Table 4 .
Percentage growing bulb and shoot emergence of shallot varieties after planting.

Table 5 .
Plant height of shallot varieties.

Table 6 .
Number of leaves of shallot varieties.

Table 7 .
Tuber weight and number of tubers of shallot varieties.Values followed by the same letter in the same column indicate nonsignificant differences according to DMRT at the level of 5%.