The Role of Organic Nutrients on Growth and Nutrient Uptake of Indigofera tinctoria L. in Agroforestry Systems

. Indigofera tinctoria contains secondary metabolites, namely indican, as a precursor for natural blue dye. Indican growth and precursors are highly dependent on environmental conditions, namely light intensity and nutrition. This study aims to examine the role of organic fertilizers on the growth and uptake of Indigofera tinctoria nutrients in agroforestry systems. The study was conducted using a completely randomized block design with a two-factor nested pattern. Shade trees as a nesting factor with three levels of sengon, durian and mixed trees (sengon, suren and teak). Type of organic fertilizer as a nested factor with 4 levels, namely without fertilizer, cow manure, goat manure and chicken manure. Repeat 3 times. The light intensity received by the plants under the sengon trees was 47308.33 lux, durian 10250 lux, mixed trees 21491.67 lux. Nested shade trees affect growth and nutrient uptake and nitrate reductase. The highest root biomass and nitrate reductase were under the sengon trees. The type of organic fertilizer nested in shade tree species affects growth and nitrogen nutrient uptake. Chicken organic fertilizer showed the highest number of leaves, plant biomass and nitrate reductase. Efforts to optimize the yield and production of nutrient uptake are planting in low light intensity around 10250 lux with fertilization.


Introduction
The textile industry has developed a lot in Indonesia, including batik.However, most enterprises use synthetic dyes as coloring media.The use of synthetic dyes can cause health and environmental impacts.One of the health effects of using synthetic dyes is allergic effects caused by aromatic amine compounds produced by synthetic dyes [1].In addition, the environmental impact caused by synthetic dyes is air and water pollution [2].15-50% of azo-type textile dyes do not bind the fabric during the dyeing process, so the use of these dyes is very negative for the soil microbial community [3] and for germination and plant growth [4].Therefore, reducing synthetic dyes with natural dyes is essential to ensure environmental sustainability for future generations [5].
One of the natural dyes that can be developed is a blue dye derived from the Indigofera tinctoria L plant [6].This plant is native to India and was brought to Indonesia by Europeans around 1900.The blue color of this plant is produced from leaves containing secondary metabolites, namely indican.Indican will turn into indigo after experiencing extraction [7].These secondary metabolites are labile and highly influenced by the environment.Light is the environmental factor that greatly influences indican [8].The indican content is highest at low light intensities, decreasing at higher light intensities [9].
Shading time and light intensity affect the growth, yield, and indican content of Indigofera tinctoria.An indican content of 461.67 ppm was produced in the combination of long shade treatment with a light intensity of 50% [11].One of the efforts to reduce the light received by the Indigofera tinctoria plant is implementing an agroforestry system.Agroforestry is the land management practice with inter-seasonal crops planted around or between rows of trees [12].Tree cover at a landscape scale supports the water cycle, and rainfall reduces light interception and carbon dioxide in the atmosphere [13].Light plays an important role in crop production because it affects the primary and secondary metabolic processes of plants [14].However, low light can reduce plant metabolic activity it can reduce plant biomass.Fertilization is an effort to compensate for plant growth and development at low light intensity.Based on [6], indigo content correlates with plant tissue nitrogen.However, this study aims to examine the role of organic fertilizers on the growth and uptake of Indigofera tinctoria nutrients in agroforestry systems.

Materials and methods
The research was conducted in Sepanjang Village, Tawangmangu District, Karanganyar Regency.Research with Complete Randomized Block Design with a two-factor nested pattern.Shade tree are a nesting factor with three levels: sengon trees, mixed trees (sengon, suren, and teak), and durian trees.Fertilizer application is a nested factor with four levels: without fertilizer, cow manure, goat manure, and chicken manure.Repeat three times.The shade trees used are 5-10 years old.The implementation begins with measuring the intensity of sunlight under and outside the canopy as a substitute for the intensity above the canopy, then calculating the light intercept value by the shade trees.Light intensity under the sengon tree is 47308.33lux; for durian trees 21491.67 lux and for mixed trees, 10250.00lux.
The materials used in this study were Indigofera tinctoria seeds, manure of cows, chickens, and goats, materials for analysis of nitrate reductase, and plant tissue nitrogen.Observational variables observed included: the number of leaves, root biomass, plant biomass, nitrate reductase activity, and nitrogen uptake.The number of leaves, roots and plant biomass were observed eight weeks after planting.Nitrate reductase activity was carried out using a modified Srivastava method.Tissue nitrogen analysis was carried out in the maximum vegetative phase using the Kjeldahl method [15].Data were analyzed using the F test with a level of 5% and continued with Duncan's Multiple Range Test at a level of 5%.

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Result and discussion

Number of leaves
The results showed that shade trees affected the number of Indigofera tinctoria leaves (Table 1).The highest number of leaves is under the sengon tree.This is because the light intensity under the sengon tree is higher than other trees.The results of this study are in line with research [16] the highest number of leaves is at high light intensity.The light intensity under mixed trees is very low so that leaf growth is low.Light intensity significantly affects leaf number, area, and shape [17].The number of leaves decreases in response to low light due to reduced leaf nodes and petioles [18].Fertilizers nested in shade trees affect the number of leaves (Table 1).Chicken manure nested on sengon trees showed the highest number of leaves, namely 21.It was not significantly different from the leaves in the chicken manure treatment nested on durian trees.These results indicate that chicken manure can encourage leaf growth under low light intensity.This is because chicken manure contains 1.70% nitrogen [19].Nitrogen as the main element in the synthesis of chlorophyll so that it can support the process of photosynthesis which in turn increases leaf growth [20].

Root biomass
Shade trees significantly affect root biomass (Table 2).The highest root biomass was in the treatment of sengon shade trees with a light intensity of 47308.33 lux.The intensity of light under the sengon shade tree is higher than that of other shade trees.Root biomass in the treatment under sengon trees significantly differed from mixed trees and durian trees.These results are by [21] that root biomass in full light is four times greater than biomass in low light.The results showed that root biomass decreased in low light.Root biomass reflects the allocation of photosynthetic products in the roots [22].Fertilizers nested in trees affect root biomass (Table 1).Chicken manure nested in sengon trees showed the highest root biomass of 0.40 grams.Root biomass in cow and goat manure treatments nested in sengon trees was not significantly different.The relationship between water and plants and the availability of nutrient minerals can be increased by organic fertilizer treatment [23].

Leaf biomass
Biomass is the accumulation of net photosynthetic collection in the form of proteins, carbohydrates, and lipids throughout the growing season.Biomass is based on oven dry weight because plant fresh weight fluctuates depending on plant humidity.The F analysis of variance showed that shade trees significantly affected leaf biomass at 4 WAP.The light intensity of 47308.33 lux under a sengon tree showed the highest leaf biomass at 4 WAP of 0.2833 g (Table 11).This is because the light intensity under the sengon tree is higher than that of other shade trees.This shows that the higher the light received, the better plant growth.Plant growth and productivity depend on light conditions [24].The light intensity plants receive significantly interacts with plant biomass [25].
Low light intensity causes a decrease in leaf biomass (Table 11).Shaded plants affect plant biomass.Biomass of 4 WAP in mixed shade trees decreased by 72% compared to sengon trees.This is because plants' primary response during photosynthesis completely depends on light conditions.Low light reduces leaves' photosynthetic capacity, which also affects plant biomass production.Biomass is a product of photosynthesis which relies on the availability of light to produce carbohydrates.One of the adaptations of plants in various light environments is changing photosynthesis's characteristics.Low light causes the net photosynthetic rate to decrease, resulting in reduced plant biomass [26].Low light is the main factor causing reduced biomass [27].Due to photosynthetic carboxylation, plants that receive low light will change their leaves to thinner to have a lower photosynthetic capacity.The leaf size will be directly proportional to the palisade tissue so that the leaf's thinner and the palisade tissue will also be more delicate.A thinner palisade layer will cause a smaller surface area than the mesophyll, so that it can inhibit the diffusion of CO2 from the intercellular cavity into the chloroplast.
Fertilization effect on leaf biomass 4 WAP (Table 12).Fertilization with organic fertilizers can increase plant growth with the symbiotic associations produced by fertilizers with plant roots, namely increasing the surface area of roots, and increasing the ability of plants to absorb water and nutrients [28].The results of [29] research that an increase in biomass with organic fertilizers is associated with a gradual increase in nodulation, nitrogen fixation, and nutrients.Organic fertilizers also exhibit plant growth-promoting properties, including the production of indole acetic acid [30].The results showed that chicken manure increased biomass 4 WAP.Chicken manure is beneficial in the growth of legume plants, namely increasing growth, nodulation and nitrogen fixation in soybeans under salinity conditions.Chicken manure can increase plant biomass [31]

Nitrate reductase activity
Observation of nitrate reductase used to measure the content of the enzyme nitrate reductase in plants.Nitrate reductase activity is the activity level of the enzyme in reducing nitrate to nitrite.The higher the value of nitrate reductase, the higher the nitrite formation in plants [32].Nitrate reductase enzyme activity is closely related to dry weight, total nitrogen, production, and crop yield.The results showed that tree species affected nitrate reductase (Table 4).The highest nitrate reductase in plants under durian stands was 2,388 µmol NO2/gram/hour.Several factors influence nitrate reductase activity in plants.The availability of nitrogen in the growing environment can affect the levels of nitrate reductase.The availability of sufficient nitrogen will increase the activity of nitrate reductase.

Nitrogen uptake
The results showed that the type of tree stands affected nitrogen uptake (Table 5).Durian and mixed trees showed similar absorption results.The highest nitrogen uptake in plants under sengon stands was 3.79%.Meanwhile, it shows the lowest absorption under mixed stands, namely only 3.38%.These results indicate that nitrogen uptake increases with higher light intensity.Light intensity affects NO3 absorption [33].The nutrient absorption rate is related to the growth rate.Biomass production increases and the total amount and intensity of absorption of nutrients also increases.Dry weight indicates an increase in nutrient uptake with increasing biomass accumulation.Fertilizers nested in tree stands affect plant nitrogen uptake (Table 5).Chicken manure nested under the sengon tree showed the highest absorption and was not significantly different from the treatment of goat manure nested under the sengon tree.This is because the sengon tree is a leguminous plant that can bind higher nitrogen.This type of organic fertilizer has succeeded in increasing nitrogen uptake because organic fertilizer has various elements needed by plants, especially nitrogen.

Conclusion
Shade trees affect growth and nutrient uptake, and nitrate reductase.The highest root biomass and nitrate reductase were under the sengon trees.The type of organic fertilizer nested in the shade tree species affects the growth and uptake of nitrogen nutrients.Chicken organic fertilizer showed the highest number of leaves, plant biomass, and nitrate reductase.Efforts to optimize yield and production of nutrient uptake are planting at a low light intensity of around 10250 lux with fertilization.

Table 1 .
Effect of tree species and fertilizer nested on tree species on leaf number

Table 2 .
Effect of tree species and fertilizer nested on tree species on root biomass

Table 3 .
Effect of tree species and fertilizer nested on tree species on leaf biomass

Table 4 .
Effect of tree species and fertilizer nested on tree species on nitrate reductase activity

Table 5 .
Effect of tree species and fertilizer nested on tree species on nitrogen uptake