GROWTH AND YIELD OF SHALLOT UNDER SEVERAL LEVELS OF SOIL WATER TABLE

The research was aimed to evaluate differences on growth and yield of two shallot varieties under several levels of soil water table. It was conducted in experimental field and plastic house of Agriculture Faculty, Universitas Sriwijaya for three months in 2019. Materials used were shallot bulb from Tajuk and Pancasona varieties and biochar originated from oil palm empty fruit bunch. Factorial Randomized Block Design was used with two treatment factors and three replicates. First treatment was 2 shallot variety consisting Tajuk and Pancasona variety. Second treatment was level of soil water table including T 0 = 0 cm below soil surface; T 1 = 10 cm below soil surface; T 2 = 15 cm below soil surface; and T 3 = 20 cm below soil surface. The observed parameters consisted of plant height, leaf number, tiller number, total bulb fresh weight, bulb fresh weight, bulb dry weight, bulb number, bulb diameter, and root length. Results showed that shallot growth of Pancasona and Tajuk variety was highly affected by levels of soil water table. It was then concluded that Pancasona variety showed better growth performance and yield compared to Tajuk variety. The deeper soil water table reaching 20 cm below soil surface can reduce growth and yield of shallot.

coverage areas of non-tidal swamp in Sumatra reaching 2.98 millions ha.From the total, there are about 368,690 ha of non-tidal swamp area cultivated as rice field, consisted of 70,908 ha of shallow swamp, 129,103 ha of middle swamp, and 168,670 ha of deep swamp.While the rest for about 2.60 millions ha are not yet utilized.In 2019, government optimization program of 500,000 ha swamp -both non-tidal and tidal swamp-includes South Sumatra, along with other five provinces which are South Kalimantan, South Sulawesi, Lampung, Jambi and Central Kalimantan.South Sumatra and South Kalimantan are considered as the most ready provinces (Rajagukguk, 2019).
Up until now, non-tidal swamp development is still not optimal due to its flooding problem with various water depths and flooding durations.Flooding have a great impact on environment and yield (Jackson and Ismail, 2015;Malik et al., 2015).Main challenge for nontidal swamp cultivation is how to optimize seasonal water availability.The land can be flooded for several months during rainy season so that it can be utilized for cultivation and also is suffered from drought in dry season (Meihana et al., 2019a).Anoxia condition occurs during flooding, while hypoxia occurs when water depth is less than 20 cm (Malik et al., 2015;Meihana et al., 2019b).
Shallot growth demands a growing media containing crumble soil structure and sufficient organic matter with non-acid soil pH for about 5.6-6.5 (Sumarni and Hidayat, 2005; Kurnianingsih et al., 2018a; Kurnianingsih et al., 2018b).Generally, shallot will not have optimal growth when being cultivated in rainy season.Main factor for the problem is water availability.Susilawati et al. (2018) reported that the combination of 60% of soil and 40% cow manure for growing media resulted in the best shallot growth and yield with average of 84.36 g of dry weight bulb per clump.In contrast, shallot cultivation during dry season will face water shortage problem.However, it is necessary to evaluate how deep soil water table in order to be able to support shallot growth.Research study by Susilawati and Lakitan (2019) resulted that the best performing snap bean growth and yield was obtained in 20 cm of water depth below soil surface.Thus, this research then was conducted to evaluate the difference of growth ability and yield of two shallot varieties under several levels of soil water table cultivated in polybags.

METHODS OF RESEARCH
The research was conducted in experimental farm and in plastic house of Agriculture Faculty, Universitas Sriwijaya Indralaya in Ogan Ilir, South Sumatra.While laboratory works were carried out in Laboratory of Plant Physiology, Agronomy Department, Universitas Sriwijaya Indralaya.The research was conducted for three months in 2019.Materials used consisted of shallot bulbs from Tajuk and Pancasona varieties, biochar from oil palm empty fruit bunch, paper bag and polybag.Research tools consisted of hoe, gauge, plastic buckets, measuring glass, analytical scale and oven.Factorial Randomized Block Design was used with two factors and three replicates.First factor was shallot variety: V 1 = Tajuk variety; and V 2 = Pancasona variety.Second factor was soil water table: T 0 = 0 cm below soil surface; T 1 = 10 cm below soil surface; T 2 = 15 cm below soil surface; and T 3 = 20 cm below soil surface.
Planting media was alluvial top soil cleaned and sieved before putting into the polybags of 10 kg volume.Biochar then was mixed into the media one week before planting with the dosage of 20 tons per ha.Shallot bulbs from Tajuk and Pancasona variety were obtained from Brebes.Before planted, the bulbs were cut in 1/3 from the edge and then planted into the media in 2-3 cm depth.One bulb was planted into each polybag.The polybags containing shallot bulbs then were soaked into plastic bucket filled with water according to the water table treatments and then put in the plastic house.
Water table in the bucket was maintained as the treatments by adding water every evening.Shallot plant treated with water table treatment only survived for 11 days, so the polybags then were taken out of the bucket in the 12 th day.After taken out, polybags were still placed in the plastic house until 30 days.Polybags then were placed outside plastic house in 31 th day.Parameters observed consisted of plant height, leaf number, and tiller number which were all measured from 3 -38 days after treatment (DAT) and total plant fresh weight, bulb fresh weight, bulb dry weight, bulb number, bulb diameter, root length and added water volume.
Resulted data then were statistically analyzed using analysis of variance (ANOVA) by comparing the resulted F value to F table.When resulted F value less than F table at 5%, it means that the treatment has insignificant effect.While significant effect is obtained if F value is bigger than F table at 5% level.Furthermore, very significant effect is obtained if resulted F value is more than F table at 1% level.Least significant difference test then used to analyze the data that showed significant and very significant effect.

RESULTS OF STUDY
Based on analysis of variance, it was resulted that levels of soil water table had significant effect on growth and yield of two shallot varieties as seen in Table 1.Difference on varieties showed very significant effect on plant height at 24 DAT and 31 DAT, tiller number at 0 -24 DAT, and root length, while soil water table treatment only showed significant effect at 24 DAT.The combination of variety and soil water table treatment had insignificant effect on all observed parameters, except for plant height at 3, 24, and 31 DAT, and also for tiller number at 3 -17 DAT.
The difference on soil water table showed insignificant effect on growth of two shallot varieties for 11 days after planting, as seen in several parameters such as plant height, leaf number and tiller number at 0 DAT.Based on average data, V 1 (Tajuk) had shorter height compared to V 2 (Pancasona) from 0 to 24 DAT, the difference between these two varieties were significantly showed at 31 DAT.Water table treatment showed insignificant effect on plant height at all plant ages, except at 24 DAT.The difference on leaf number parameter was started to appear from 0 to 17 DAT but was statistically significant at 24 and 31 DAT.Leaf number was not affected by soil water table treatment (Table 2).
Similar with plant height and leaf number, Pancasona also showed better result in tiller number compared to Tajuk variety.Besides, soil water table treatment also did not show any effect on tiller number.However, tiller number of these two varieties statistically showed significant difference started from 0 to 24 DAT, except at 31 DAT.Root length of Tajuk and Pancasona was significantly difference, while soil water table at 0 cm also showed significant difference compared to other depth treatment (Table 3).Soil water table treatment showed very significant effect on growth of two shallot varieties as seen in the parameters of plant height at 3, 24 and 31 DAT and tiller number at 3, 10 and 17 DAT.Least significant difference (LSD) test on 5 % level showed on three different plant ages showed that the lowest plant height result was obtained from the same combination treatment which was V 1 T 3 with 14.52 cm at 3 DAT, 18.17 cm at 24 and 31 DAT.The same pattern was also resulted in tiller number where the lowest result was on V 1 T 1 (Tajuk variety with 10 cm of water table below soil surface) with 2.5 at 3 DAT, 3.0 at 10 DAT and 3.33 at 17 DAT.The lowest result was all obtained from the same variety which was Tajuk variety (Table 4).The numbers followed by same letter in the same row means insignificant difference.The numbers followed by same letter in the same row means insignificant difference; nm=not measure.
Shallot variety showed significant effect on yield component as obtained from the parameters of bulb fresh weight, bulb dry weight, bulb diameter and harvest index, while water table treatment had significant effect on total plant fresh weight (shoot + bulb) and bulb fresh weight.The Numbers followed by same letter in the same row means insignificant difference.The difference on shallot variety gave significant effect on yield component since planting for 11 days.Total plant (shoot + bulb) fresh weight of Pancasona was higher than Tajuk in all water table treatments.The lowest weight was obtained from 20 cm of water table below soil surface treatment.Control treatment (without water table treatment) of two varieties had higher weight compared to other treatments with 18.17 g and 21.83 g for Pancasona and Tajuk variety (Figure 1).Similar to total plant fresh weight, bulb fresh and dry weight both had the same pattern where the combination treatments of Tajuk showed a lower result compared to Pancasona.The highest weights from both varieties were obtained from control (without water table treatment) with 12.33 g and 18.00 g of bulb fresh weight and 10.00 g and 12.66 of dry weight for Tajuk and Pancasona, respectively (Figure 2 and 3).

DISCUSSION OF RESULTS
Based on the research, it was resulted that two observed shallot varieties still could tolerate water table condition until 20 cm below soil surface as seen from their growth for 11 days started from planting (Table 1).Table 2 also indicates that there was no significant difference of growth parameters under different levels of soil water table.Along with this result, Susila et al. (2013) reported that Bima Brebes shallot variety still could increase its yield even with 25 cm of water table below soil surface.
Tajuk variety generally had lower growth ability compared to Pancasona as seen in all growth parameters.Based on variety description, Tajuk is shallot variety introduced from Thailand that suited to be cultivated in lowland area in Nganjuk Regency.While Pancasona is a shallot variety bred by Vegetable Research Center that can well adapt in lowland area with 6-85 m above sea level.A relatively high ability of growth component was plant height which was only effective at the end of growth phase compared to leave number affected by 24 DAT to 31 DAT, moreover tiller number affected since 0 DAT to 31 DAT.
Generally, results showed that shallot could grow and have better yield under normal water condition (control treatment) as can be seen in vegetative phase shown by   2019) about the use of biochar at different levels of soil water table towards shallot, there was a contradictive result where shallot still could grow well at the water depth until 20 cm below soil surface when provided with biochar treatment.This was assumed that the addition of biochar had improved water binding capacity of the planting media, so there was adequate water supply for the plant.In accordance with the vegetative phase, yield components result had rather similar pattern in which the highest total plant weight (shoot and bulb) and bulb fresh weight and bulb dry weight was obtained in Pancasona variety compared to Tajuk variety.Likewise, at the treatment of water table, the yield was decreasing with the depth until 20 cm below soil surface (Figure 1-3).However, this condition is also contradictive when biochar was added to the planting media.This was due to biochar originated from oil palm empty fruit bunch was composed by 25.6% of C-organic and 19.4 of C/N ratio which could improve soil physical characteristics (Santi dan Goenadi, 2012).This condition resulted in better plant growth and development for both shoots and bulbs.The use of biochar was considered would be very helpful in improving soil under less optimum conditions as in this research where water availability was limited.Another research mentioned that there was a huge biomass increase if the biochar was given to the soil without fertilizer (infertile soil) compared to the soil with fertilizer (Haefele et al. 2011;Carter et al. 2013).

CONCLUSION
Based on the results, it was concluded that Pancasona variety had better growth compared to Tajuk variety under several levels of soil water table.Soil water table of 20 cm below soil surface could decrease the growth and yield of shallot for both Pancasona and Tajuk variety.

Figure 1 -Figure 2 -Figure 3 -
Figure 1 -Total plant fresh weight (shoot + bulb) of two shallot varieties Dou et al. (2014)  stated that the addition of biochar affected soil physical characteristics which could increase water absorption capacity thus could directly affect wider root development zone resulted in the plant's amenity to get water and nutrition need for its growth.The other research result showed that the use of biochar sized less than 1 mm had better effect than biochar sized 1 or more than 1 mm on rice growth(Kartika et al., 2018;Kartika et al., 2019).The condition of 20 cm water level below media surface had better probability for the root to grow and develop as there was soil pore filled with oxygen due to the addition of biochar.A research result by Lakitan et al. (2018) stated that bean's root could not survive in a water saturated condition.

Table 1 -
The effect of soil water table on vegetative growth of two shallot varieties Note: DAT = day after treatment; ns = not significantly different; * = significantly different at p < 0.05; and ** = significantly different at p < 0.01.

Table 2 .
Plant height of two shallot varieties due to soil water table treatment

Table 3 -
Tiller number and root length of two shallot varieties due to soil water table treatment

Table 4 -
Combinations of variety and soil water table treatment on plant height and tiller number

Table 5 -
The effect of soil water table on yield component of two shallot varieties

Table 2 -
3where the plant height, leaf number, and tiller number had some decreases under soil water Two shallot varieties under different levels of soil water table(-cm) table treatment especially in 20 cm of water table below soil surface.This showed that the water table until 20 cm below soil surface did not support shallot growth.Based on a research by Susilawati et al. (