Genetic advantages of highland local rice in South Sumatra

Identification of genetic superiority is needed to anticipate problems such as local rice extinction and environmental stress due to global climate change. This study aims to determine the genetic superiority of local upland rice in South Sumatra, and the opportunities for its use as a donor gene in the creation of new high-yielding varieties. A research on eight local rice was conducted in May-September 2021. The method and scope of the study are inventory of local rice, identification of agronomic characters, and identification of Zn and Fe content in grain components. Quantitative characters identified as important genes are panicle length and 1000 grain weight. Panicle length (>35 cm) is an important character of Selebur Rimbe, Putih Rice and Jambat Teras. The 1000 grains weight of Selebur Rimbe rice is close to 30 g (28.95 g). The [Zinc] character of local rice bran significantly determines [Zn] polished rice (r = 0.701*). While determining character [Fe] of brown rice is empty grain (r = - 0.707*). Information on the advantages of this rice genetics can be utilized through implementation of crosses with various superior varieties of rice. The expected output from this effort is a superior rice variety that has characteristics including high yield, high [Zn] brown rice grains, low [Fe] husk, as well as adaptive and stable at various altitudes.


Introduction
Genetic resources (GR) is one of the bases in agricultural development.The implementation of GRbased development requires biotechnology and technology support, including in the creation of new superior varieties (NSV).This effort can be implemented through plant breeding programs.Genetic advantages can be identified and can be created through transformation of the desired gene, genetic biofortification, mutation breeding or through conventional breeding [1][2][3][4].
The source of superior genes desired plants and relevant to overcoming the constraints of abiotic and biotic environmental stress as well as stress because of global climate change is landraces [5,6].In South Sumatra, local rice has been tested to be adaptive in upland dryland through hereditary cropping and still exists today.However, the potential of this genetic resource has not been utilized optimally and has not been widely developed and is even threatened with extinction.
Various local rice varieties with other specific advantages that still need to be explored are the nutritional content of Zinc and Fe in rice.These micronutrients available in the soil are absorbed and accumulated by plants in biomass and seeds.Grains with high zinc nutrition are needed for human health (growth, immune system, and intelligence).Implementation of the Zn enhancement program in
The largest upland dryland is in Sumatra (10.427 million ha).Of this area, 841.37 thousand ha are found in South Sumatra.With rainfall >2000 mm/year, this land is classified as a wet climate.There are obstacles to rice farming in this agro-ecosystem, especially when accompanied by the impact of global climate change.These constraints include acid soil (pH <5.5), low soil fertility, flooding, drought and pest and disease attacks.Short-term efforts to overcome these obstacles are through the use of NSV tolerant and high yielding on some of these constraints.The tolerant NSV technology produced by the Ministry of Agriculture is available, but this NSV has not yet been developed at the farm level because farmers prefer local rice.Based on this, one of the factors that will influence the adoption of varietal technology by farmers is the availability of NSV which is similar to the local varieties commonly grown by them but is superior in terms of shorter lifespan and higher productivity.Thus, a long-term effort that can be carried out is by assembling NSV based on local varieties as donor genes.

Inventory and characterization of local upland rice
The results of an inventory of local rice varieties in the highlands of Muara Enim Regency (Table 1), there are eight local varieties that are almost extinct, namely Bengkok Buku, Ulu Danau, Lelak Daun, Karet Rice, Putih Rice, Selebur Urik, Selebur Erum, and Beram Rice.Meanwhile, the local varieties that are still grown from generation to generation are Selebur Rimbe and Jambat Teras.
Local varieties that are almost extinct occur because these local varieties have several weaknesses, including low yields, longer shelf life and non-storable (hard) rice.Nonetheless, these varieties which are on the verge of extinction have genetic advantages, including adaptability at altitudes >1300 meters above sea level (masl) and grain storage resistance (>6 months).At that altitude, the local rice yield is higher and the rice tastes better.This genetic advantage can be used as a donor gene in the assembly of NSV.
Eight GR of local rice which is almost extinct needs to be preserved because it has specific advantages.This advantage can be exploited through the implementation of crosses with local rice that is still cultivated by farmers today (Jambat Teras and Selebur Rimbe) or crosses with various superior varieties of released rice.It is hoped that from the results of the crosses, varieties that have the desired advantages (short-lived, high yields, adaptive and stable at various heights) will be obtained.Opportunities for cultivating superior rice in upland agro-ecosystems are the production of varieties that have the characteristics of grain and rice that are resistant to storage, disease resistant, have a shorter lifespan (<6 months after planting) and are rich in micronutrients, including zinc nutrition.

Genetic advantages of local highland rice
Genetic superiority of local upland rice was identified through quantitative characterization of each local variety.Characterization is carried out per individual plant and refers to the Guidelines for Observing Characteristics of Local Variety Plants and Breeding Results [10] and Guidelines for Compiling Descriptions of Food Plant Varieties [11].
In assembling new high-yielding varieties, the important genes desired from the parents include panicle length >35 cm and 1000 grain weight >30 g [13].The important panicle length gene is present in four local rices except Beram Rice.Besides being superior in panicle length, local rice Selebur Rimbe also has a weight of 1000 grains close to 30 g (28.95 g).Based on this quantitative advantage, the local rice Selebur Rimbe, Putih Rice and Jambat Teras are potential gene donors in the creation of new superior varieties specific to upland dryland.

Nutrient content of Zinc and Fe in grain components
Rice products produced by local rice contain micronutrients, including Zinc and Fe.Another advantage of local rice is that it is tolerant to biotic and abiotic stresses.Thus, besides having the potential to increase nutrient intake, these varieties have the potential to be developed to overcome constraints on marginal land and overcome the dynamics of climate change.
The content of Zinc and Fe in the local rice grain components of Selebur Rimbe, Jambat Teras and Selebur Urik at an altitude of 1200 meters above sea level is quite diverse (Table 3).Zinc content in brown rice, husk, empty unhulled rice and milled rice ranges from 20.10-24.90mg/kg, 3.60-5.60mg/kg, 12.10-15.60mg/kg, and 17.70-22.10mg/kg, respectively.The grain components contain Fe around 10.00-11.38 mg/kg in brown rice, 12.40-30.90mg/kg in husks, 15.70-35.70mg/kg in empty grain, and 5.60-7.10mg/kg in milled rice.An indicator of the superiority of local rice can be identified from the low level of zinc loss in rice due to the milling process.The average zinc loss in rice due to milling was 13.83% (8.299-18.072%) in Selebur Rimbe, 17.52% (15.023-21.811%) in Jambat Teras, and 6.81% (5.911-8.04%) in Selebur Urik.From the reported research results, rice Zn losses due to polishing still varied, namely 19% [14], 45.5% [15], and 20-40% [16].Loss of zinc nutrition due to polishing because Zn minerals are located in the aleurone layer [17].The standard value for zinc nutrient loss due to milling is 20% [14].The loss of Fe due to milling was around 53.41% [15].Data in Table 4 shows that the percentage of loss of Fe in rice was around 39.12-48.10%,while the percentage of loss of Zn in polished rice was around 6.81-17.52%.These results indicate that the increase Zinc in grain rice through the utilization of rice local as the parent in the assembling of new superior rice is very prospective to be implemented.Regression test on these three varieties showed that there was a significant positive correlation between [Zn] in brown rice and [Zn] in polished rice.The regression equation between these two variables is y = 0.4375x + 8.7926 (Figure 1).A significant negative correlation was found between [Fe] of empty grain and [Fe] of brown rice.The regression equation between these two variables is y = -0.2366x+ 16.54 (Figure 2).These results indicate that, [Zinc] character of local rice bran significantly determines [Zn] polished rice (r = 0.701*).While determining the character [Fe] of brown rice is empty grain (r = -0.707*).Information on the advantages of this rice genetics can be utilized through the implementation of crosses with various superior varieties of rice.The expected output from this effort is a superior rice variety that has characteristics including high yield, high [Zn], low [Fe] husk, as well as adaptive and stable at various altitudes.Local varieties that are almost extinct occur because these local varieties have several weaknesses, including low yields, longer shelf life and hard rice.Even though it is almost extinct, this local rice has genetic advantages, including being adaptive at altitudes >1300 meters above sea level and grain storage resistance (> 6 months).At that altitude, the local rice yield is higher and the rice tastes better.This genetic advantage can be used as a donor gene in the assembly of NSV.
Quantitative characters identified as important genes in local rice Selebur Rimbe, Beram Rice, Putih Rice were panicle length and 1000 grain weight.In assembling NSV, the important genes desired from the parents include panicle length >35 cm and 1000 grain weight >30 g.The important panicle length gene is present in four local rices except Beram Rice.Besides being superior in panicle length, local rice Selebur Rimbe also has a weight of 1000 grains close to 30 g (28.95 g).Based on this quantitative advantage, the local rice Selebur Rimbe, Putih Rice and Jambat Teras are potential gene donors in crosses with released NSV.It is hoped that from the results of the crosses NSV will have the desired advantages, including shorter life, higher yields, adaptive and stable at various heights.
The [Zinc] character of local rice bran significantly determines [Zn] polished rice (r = 0.701*).While determining character [Fe] of brown rice is empty grain (r = -0.707*).Information on the advantages of this rice genetics can be utilized through implementation of crosses with various superior varieties of rice.The expected output from this effort is a superior rice variety that has characteristics including high yield, high [Zn] brown rice grains, low [Fe] husk, as well as adaptive and stable at various altitudes.

Table 2 .
Characterization results of four local rice varieties in Muara Enim Regency, South Sumatra

Table 3 .
Zn and Fe content in local rice grain components in Muara Enim Regency, South Sumatra