Uniformity test of the upland rice lines F 8 from crosses of local Bangka rice and lodging resistance superior varieties in Belitung Regency

. Lodging on plant rice can lead to reduces yields. Developing rice varieties with lodging resistance can do through the breeding activities. Crossing between local Bangka rice and lodging resistance superior varieties have been carried out and obtained F 8 lines of upland rice. Before releasing the rice lines released into varieties, it must meet the high uniformity criteria. This research aims to determine the uniformity level of F 8 upland rice lines. This research was conducted using an experimental method. The design used a randomized block design with 10 treatments (5 F 8 lines and 5 comparison varieties). The F 8 lines used 19I-06-09-23-03, 21B-57-21-21-23, 23F-04-10-18-18, 23A-56-20-07-20 and 23A-56-22-20-05. The comparison varieties used i.e. Danau Gaung, Inpago 8, Inpago 12, Rindang and PBM UBB 1. The research data were analyzed using qualitative descriptive, variability test, uniformity test, and Least Significant Increase (LSI) test. The result showed that F 8 lines of upland rice had narrow genotypic and phenotypic variability values in all characters observed. The percentage of uniformity was obtained in the range between 83.3-100%. It shows that the F 8 lines had a high uniformity. F 8 lines of 19I-06-09-23-03, 21B-57-21-21-23, 23F-04-10-18-18, and 23A-56-20-07-20 showed 100% uniformity level in plant height, flag leaf length, panicle length, productive tillers number, and filled grains number. The result of LSI test obtained 23A-56-22-20-05 and 23A-56-20-07-20


Introduction
Rice is an important food crop for people worldwide [1].Rice is the major food commodity in Indonesia [2].Efforts to reduce rice imports can be carried out, one of which is through local rice plant breeding activities.
Bangka Belitung Islands Province has as many as 26 accessions of local rice that have been found [3].According to Mustikarini et al [4], local rice has the advantage of being resistant to biotic and abiotic stress.[5] stated that in addition to having the advantages, local rice Bangka also has several disadvantages, including easy lodging, long harvest, and low yield [6].The occurrence of strong winds and heavy rains increase the frequency of crop lodging.
Crossbreeding activities between local Bangka rice and varieties with lodging resistance have been carried out and obtained F8 lines of upland rice.The upland rice plant lines have changed to the degree of variability over several generations.The test of lodging resistance rice has been carried out by obtained a second generation (F2) that has broad variability values in the character of the grain number, grain weight, plant height, and productive tillers number [3].According to Mustikarini et al [7], the fourth generation (F4) had a flowering time and harvest time with a narrow variability value.[8] continued research and obtained the sixth generation (F6) resulting in a narrow genotype variability value in the character of plant height, leaf length, and seed weight for each plot.The results of the study of [9] in Bangka Island, obtained line F7 of 23F-04-10-18-18 have high uniformity and yield production.
One of the conditions that must be met for a plant line to be released as a new superior variety is that the population in the line must be uniform.According to [10], uniformity indicates the degree of homogeneity in a plant.[11] stated that uniformity lines are of utmost importance in rice breeding.[12] stated that uniformity tests were carried out to ensure that the seeds of a plant variety had the characteristics of not deviating at the time they had been released as a variety.The level of plant uniformity can also be seen from the variability value.According to [13] variability is one of the genetic parameters that identify diversity in the population.[14] stated that low genetic diversity indicates that the rice genotype population has high uniformity.This research was conducted to determine the highest level of uniformity in several F8 lines of upland rice.The results of this study are expected to obtain an F8 line with high uniformity, which is required to release new high-yielding varieties.
The observed characters are divided into qualitative and quantitative characters.Qualitative characters include the lodging index, leaf surface texture, leaf color, leg color, stem color, rice epidermis color, and rice shape.Quantitative characters include plant height, productive tillers number, flag leaf length, flowering age, panicle length, harvest age, filled grains number, and filled grains number for each plot.Qualitative data are analyzed descriptively and presented in the form of tables and figures.Quantitative data were analyzed using the ANOVA with a 95% confidence level followed by variability testing, uniformity test, and Least Significant Increase (LSI) test.The variability value can be calculated by analyzing the middle-squared variant first, then calculating the value of the genetic, environmental, and phenotype variant or variety.The upland rice genotype has kinds of colors is leaf, stem, leg, and epidermis.The shape upland rice genotype rice has two kinds of shapes, namely slender and medium (Figure 1).The surface texture of upland rice genotype leaves has 3 kinds of textures.The upland F8 rice line has the same lodging index of 0% or is very resistant to lodge.The PBM UBB 1 and Danau Gaung variety has lodging index including sensitive plants (Table 1).The F8 lines of upland rice had narrow genotype and phenotype variability values in all characters (Table 2).The narrow variability value indicates that all the characters tested in the F8 generation have had high uniformity.[15] stated that uniformity testing is determined by the magnitude of the variation that occurs in a population, the smaller the variation, the higher the uniformity and conversely.[16] stated that homogeneity in the observations made showed that the population has been uniform.According to [17], if the character of the tested line shows uniformity, it can be assumed that the character in the line is stable.Note : "Genotypic variability" σ²g ≥ 2 (σ σ²g) = wide, σ²g < 2 (σ σ²g) = narrow; "Phenotypic variability" σ²f ≥ 2 (σ σ²f) = wide, σ²f < 2 (σ σ²f) = narrow.
The range of uniformity percentages in the F8 lines tested was 83.3-100%.Lines is indicating characters have 100% uniformity.Line 23A-56-22-20-05 has 5 uniform characters, namely plant height, flag leaf length, panicle length, filled grain number, and the filled grain weight for each plot, a non-uniform character of the productive tillers number (Table 3).[18] stated that self-pollinating plants will experience an increase in homozygosity.Generation F8 is the 7th generation of segregation, the homozygous percentage is 99.21%.[15] stated that a plant is considered uniform if the properties possessed remain the same even though it is planted in different environments.[19] stated that genotypes with a uniform character mean that selection activities in these characters no longer need to be selected, because the phenotype of these characters is already consistent.
The plant height of lines is shorter than the plant height of the comparator varieties subtracted LSI value (Table 4).Line 23A-56-20-07-20 has a lower plant height than Danau Gaung and PBM UBB 1.According to [20], the height of upland rice plants is classified into short (<90 cm).[21] stated that plant height is the main factor causing lodging in plants.[22] stated, that the higher the plant, the higher the tendency to fall.[6] stated that strong winds and high rainfall can cause a fall in rice plants.The Danau Gaung variety experienced a lodging of 76.25% and the PBM UBB 1 variety experienced a lodging of 91.14%, resulting in yield loss due to the large number of vacuous seeds produced.[23] stated that Lodging in rice often limits grain yield and quality.Note : 1. SD value < sd comparator = uniform (U), sd value > sd comparator = non-uniform (NU).2. Comparative varieties are: Danau Gaung, Rindang, PBM UBB 1, Inpago 8, Inpago 12 The character of the number of productive saplings of the F8 line ranges from 10.76-24.30tillers.There is 1 line of offspring that has more productive tillers than the comparison variety, namely line 23A-56-22-20-05.[24] stated that the number of productive tillers in planting is one of the important things related to the grain yield of rice plants.According to [25], to increase grain yield, a genotype must have a greater number of tillers.Reinforced by the opinion of [26] productive tiller number of a rice plant is related to panicle number.The greater the number of tillers and panicles produced by rice plants, the more grain produced by rice plants will also be.The character of the flag leaf length of the F8 lines ranges from 21.06-26.65 cm.The longest flag leaf length is line 23A-56-20-07-20.The results of the LSI test showed that the length of the flag leaf of the F8 line of upland rice was not better than the comparison varieties.[27] stated that the length of the flag leaf can be used as a potential phenotypic marker for high production yields.According to [28], flag leaf has a great effect on the yield of rice.[29] stated that flag leaves provide the most important source of photosynthetic energy during grain reproduction and filling.The panicle length character of the F8 lines of upland rice ranges from 17.90-20.67cm.According to [20], panicles are five grouped.The data showed that the length of the panicle line F8 belonged to the medium group.[30] stated panicle length will affect the amount of grain produced and affect the amount of yield.
The flowering age of the tested F8 lines ranges from 67.6-77.6 days after planting.The harvest age range of the F8 lines of upland rice is between 104.6-112.6 days after planting.[31] stated the timing of flowering is determined by endogenous genetic and environmental.According to [32], the flowering age is related to the harvest age.The age of the harvest is influenced by the speed of flowering plants, the faster the plant blooms, the faster the plants will harvest [33].
The character of the number of filled grains indicates that the F8 line of upland rice is no better than the comparison varieties.According to [34] in addition to genetic factors, environmental factors also affect the number of filled grains of each panicle.[35], the ability of plants to produce the number of grains is also influenced by the number of tillers and the length of the panicles.
The weight of filled grains in each plot of the F8 lines of upland rice ranges from 4.70-6.78kg /plot.Grain filling rate is affected by external environmental conditions, pest and disease attacks [36].According to [37], the weight of filled grains for each plot is also influenced by the genetics of the character of elders.

Table 1 .
Qualitative character of lines F8 of upland rice plant.

Table 2 .
Variability value of upland rice F8 line.

Table 4 .
Result of LSI test.The letter in parentheses is a symbol to indicate the check rice varieties; g = average value of F8 lines; The test lines are better than the check plant when the value of lines ≥ the value of the check + LSI, except for plant height, flowering age, and harvest age is better when the value of lines ≤ the check value -LSI.