The Role of Root and Tuber Crops on Food Diversification Facing the Climate Change in East Java Indonesia

Root and tuber crops consisting of cassava, sweet potato, potato, taro and others root and tubers have the important roles as the source of food, nutrition and cash income for many farmers in Indonesia. These crops also as a source of carbohydrates beside rice, corn, cereals, wheat etc. Root and tuber crops are the second most important group of crop plants after the cereals. The government of Indonesia accelerate food diversification based on local food resources, especially facing the climate change. The objective of this study was to estimate the role of root and tuber crops on food diversification and to estimate the household root and tuber crops demand in East Java Indonesia. The research used SUSENAS (Indonesian National Socio-Economic Survey) 2020 data with 31.990 household respondents in East Java Indonesia. Demand for food was estimated by AIDS (Almost Ideal Demand System) model. The results show that the average consumption for root and tuber crops was 0,69 kg/household/week (11,23% from carbohydrates foods), whereas rice consumption amount 4,86 kg/household/week (79,68 %), maize amount 0,25 kg/household/week (4,13%) and cereals amount 0,3 kg/household/week (4,96%). The expenditure elasticity of root and tuber crops was 1,36, while the expenditure elasticity of rice amount 0,78 (normal food), maize (1,41) and cereals (1,27). The expenditure elasticity more than 1 means that root and tuber crops as a superior food, also for maize and cereals. People no longer considers that root and tuber crops to be an inferior food. The root and tuber crops consumptions have the highest proportion after rice. It can be mean that root and tuber crops have the important role on food diversification in East Java Indonesia. Facing the climate change, root and tuber crops development be a right decision, moreover, root and tuber crops can be planted on dry land which is still widely available in Indonesia.


Introduction
Climate change, environmental damage and lack of implementation of food diversification are some of the fundamental problems in the agricultural development of East Java Province [1].Currently, East Java Province is a national food buffer with an average contribution percentage of horticultural crop production of more than 35 percent and food crops consisting of rice at 17.93 percent, corn at 28.91 percent and soybeans at 39.30 percent in 2020 [1].Climate change is characterized by an increase in air temperature, changes in rainfall and a rise in sea levels [2,3,4].Climate change is a threat to water resources [3].This can increase the potential for droughts and floods which will have an impact on the agricultural sector in the form of changes in cropping patterns, the explosion of pest attacks and plant diseases, reducing soil fertility and plant productivity [5].Climate change increases stress on food crops [6].In facing climate change, it is necessary to develop alternative food sources that are more adaptive to the specific environmental and social conditions of the society, thus the society is able to sustainably maintain the availability of food sources, nutrition, and income, especially for farmers.Rice has become the primary and first staple food in Indonesia [7,8,9].Food diversification is an effort to reduce people's consumption dependence on one dominant type of food [10,11].There are several aspects to consider in food diversification including aspects of consumption, food business development, production and food independence [11].Food diversification with alternative sources of carbohydrates is a solution during the food crisis in Tidore [7].These alternative carbohydrates sources can be root and tuber crops consisting of cassava, sweet potato, potato, taro and others root and tuber have the important role as the source of food, nutrition and cash income for many farmers in Indonesia.These crops included in the orphan crop and also as a source of carbohydrates besides rice, corn, cereals, wheat etc.In several developing countries, orphan crops has a vital role by generating revenue for smallholder farmers [12].Root and tuber crops are the second most important group of crop plants after the cereals.Sweet potato is tolerant of drought conditions, it is able to maintain hydration longer in drought conditions because of its productive root system [6].Cassava is the fourth most important food crop in the developing countries after rice, wheat and maize.It also one of the most important sources of commercial starch and the second most important source of starch worldwide after maize because of its high grade, excellent thickening, neutral taste, desirable texture, and relatively low cost [13].Food diversification and incorporation of resilient crop species such as an orphan, minor, or underutilized into food systems will ensure food and protein security in many parts of Africa [12].The objective of this study was to estimate the role of root and tuber crops on food diversification and to estimate the household root and tuber crops demand in East Java Indonesia.To estimate household demand of root and tuber crops in East Java, Indonesia was used Seemingly Unrelated Regression (SUR) Method with Linear Approximation/Almost Ideal Demand System (LA/AIDS) model.

Research Methods
The data needed is in the form of consumption module data and core data in the March 2020 National Socioeconomic Survey (SUSENAS).Consumption panel Susenas data is cross section data with a sample of household units.This study will conduct a research econometric approach with the LA-AIDS (Linear Approximation Almost Ideal Demand System) model and estimation uses SUR (Seemingly Unrelated Regression).
Commodities taken in this research include carbohydrate food commodities, namely: rice, corn, grains, tubers, bread and ready-made food.Because the prices actually paid by households are not reported in Susenas, unit prices are obtained by dividing household expenditure by the amount purchased.The LA-AIDS equation developed by [14,15] as follows: Where:

Wi
= the expenditure proportion on the i-th commodity group    = regression parameter for intercept value, aggregate price and output of each commodity P = price of cabohydrate food   = estimated price of the j-th commodity group  [14,15] as follows: Measuring changes in demand can be done through analysis of the elasticity of demand because changes in demand for commodities are caused by changes in price changes of these commodities (own price elasticity), due to changes in consumer income (income elasticity), and as a result of changes in the prices of other commodities (cross elasticity).The elasticity of demand can be analyzed using the Marshallian and Hicksian demand function approach [16].Suggests that elasticity can be calculated using the following formula: 1. Marshallian elasticity, where there is an income effect derived from total expenditure, so: Price elasticity and Marshallian cross values: Hicksian elasticity, there is only the price effect of expenditure, so the value of elasticity is known by: Price elasticity and Hicksian cross value:

The Role of Root and Tuber Crop
There are several alternative sources of carbohydrates food that will be discussed in this research, including rice, corn, grains, root and tuber crops (Table 1).This diversity of food crops can be used to face food issues and climate change problems.Table 1 shows that the average consumption for root and tuber crops was 0,69 kg/household/week (11,23% from carbohydrates foods), whereas rice consumption amount 4,86 kg/household/week (79,68 %), maize amount 0,25 kg/household/week (4,13%) and cereals amount 0,3 kg/household/week (4,96%).Rice is the main source and staple food of carbohydrates [7,8,9].In accordance with the results of this research which shows that people still depend on rice for their source of carbohydrates.Root and tuber crops have the second highest contribution as alternative sources of carbohydrate food after rice.This means that root and tuber crops have an important role as food diversification, even as orphan crop [17].Alternative sources of carbohydrates other than rice are a solution when facing food problems and climate change.This is because climate change can have an impact in the form of reducing the productivity of rice fields for producing rice.If people only depend on one source of carbohydrates, it is feared that there will be problems with food availability due to climate change, so it is necessary to diversify food ingredients to deal with these conditions.Linear Approximation Almost Ideal Demand System (LA-AIDS) model was used to estimate own price, cross-price and expenditure elasticities of root and tuber crops household demand in East Java, Indonesia.Based on the estimation results (Table 2) the elasticity value for rice expenditure in East Java, Indonesia is 0,780, including normal goods because the expenditure elasticity value is less than one (<1).This indicates that expenditure on rice will decrease as the proportion of household income increases.
Maize (1,412), grain (1,274), root and tuber crops (1,363), bread (1,349), instant and fast food (2.073) are luxury goods (>1).Expenditure elasticity greater than one indicates that the increase in consumption demand is greater than the proportion of increase in income [18,19].The difference between Marshallian and Hicksian own price elasticity is that the Marshallian elasticity value only consists of the own price value, while the Hicksian elasticity value consists of the own price value and income factor [20].Overall, the results of Marshallian and Hicksian own price elasticity values are negative (Table 3), which means that an increase in commodity prices results in a decrease in consumption demand for the own commodity, this is in accordance with the law of demand.The own price elasticity value for maize, grain also instant and fastfood commodities is worth more than one (>1), elastic.This means that demand for food commodities is significantly influenced by price changes.Households are more responsive to changes in commodity own prices than changes in prices of other commodities (cross-price) [21].Different from rice, root and tuber crops also bread are inelastic, changes in price are not significant to changes in demand for the own commodities.Table 4 shows the results of the uncompensated cross price elasticity analysis, most of which have a negative sign.This value indicates that there is a complementary relationship between the carbohydrate food groups.Hicksian cross price elasticity shows that in general the relationship between other carbohydrate food commodities has a substitution relationship with a positive value except rice to bread.The price of rice in East Java relative to corn demand is 0.015, which means there is an increase in root and tuber crops consumption of 0.015% when the price of rice rises by 1%.This is in line with the phenomenon during the covid-19 pandemic there were symptoms that the shift in consumption of staple foods again switched from rice to sago caused by the food crisis.Many people switch to eating sago which culturally has been a staple food for a long time in the islands of Tidore City.This makes it an increase and becomes an alternative to staple foods facing food crisis.One of the processed forms of yam in North Maluku is cassava starch (sagu kasbi) or sago cake (sagu lempeng) model derived from cassava.Kasbi sago consumed by the community is made from cassava.Cassava contains 359 kcal of energy, 2.9% protein, 0.7% fat, and 84.9% carbohydrates [7].

Conclusion
The diversity of food crops can be used to facing food issues and climate change problems.Root and tuber crops have the second highest contribution as alternative sources of carbohydrate food.This means that root and tuber crops have an important role as food diversification.The demand for root and tuber plants in East Java is estimated using expenditure elasticity with elastic results, the estimated own and cross price elasticity of demand is inelastic.

Acknowledgements
The authors acknowledge Brawijaya University for funding this research through "Hibah Pusat Studi LPPM UB" Program.The authors also acknowledge for all the data and information supports.
Commodities taken in this research include carbohydrate food commodities, namely: rice, corn, grains, tubers, bread and ready-made food.Because the prices actually paid by households are not reported in Susenas, unit prices are obtained by dividing household expenditure by the amount purchased.The LA-AIDS equation developed by

Table 1 .
The Average Consumption for Root and Tuber Crops in East Java, Indonesia 3.2.Estimation of Demand Elasticities for Root and Tuber Crops Using LA-AIDS Model

Table 2 .
Expenditure Elasticity on Carbohydrate Food Sources in East Java, Indonesia.

Table 3 .
Own Price Elasticity on Carbohydrate Food Sources in East Java, Indonesia

Table 4 .
Cross Price Elasticity on Carbohydrate Food Sources in East Java, Indonesia