An analysis of sex ratio value, fruit set and fruit to bunch of palm oil Socfindo MT Gano variety on mature plants (MP1, MP2, MP3)

Several studies in managing fruit sets and fruit to bunch are needed to get an ideal concept of treatment for varieties, one of which is the technical culture to explore the production potential of cultivated varieties. Therefore, this research aims to determine the sex ratio, fruit set, and fruit to bunch of palm oil bunch of Socfindo MT Gano variety on mature plants. This research was conducted using the survey method, object of research namely the 2019 planting year (3 years old), the 2018 planting year (4 years old), and the 2017 planting year (5 years old). The data collected were the number of male flowers, female flowers, stalk weight, stalk diameter, fruit, and parthenocarpy fruit, then calculated the sex ratio, fruit set, and fruit to bunch, analyzed by Analysis of Variance at a 5% level. The results indicated that the sex ratio and fruit to bunch were significantly different between MP1, MP2, and MP3, but the fruit set presented no significant difference between MP1, MP2, and MP3. The sex ratio is negatively correlated with fruit set and fruit to bunch, while the fruit set is positively correlated with fruit to bunch with an exceptional relationship.


Introduction
The productivity of oil palm plants is influenced by various factors, including the type of planting material used or known as varieties.New varieties are continuously being created to answer the problems encountered in the field.Moderate Resistant Variety (MT) Gano is one of the superior varieties distributed and marketed by PT.Socfin Indonesia to overcome stem rot disease which is an important disease in oil palm plantations.Oil palm plantations that have entered the second generation and so on are faced with the problem of high Ganoderma fungus attacks which lead to plant death.According to Syahputra and Purba, Ganoderma attacks on oil palm plantations in Indonesia will double by 2035 [1].
The Socfindo MT Gano DxP variety has the characteristics of an increasing height of 40-50 cm year - 1 , can be harvested from the age of 2 years, FFB production potential is 31-34 tons ha -1 year -1 , CPO production potential is 8-9.5 tons ha -1 year -1 , the average bunch weight is 11.8-14.2kg, the average number of bunches is 16.1-21.1bunches -1 year -1 [2].It is necessary to know the characteristics of each oil palm plant from the start to obtain predictions of cumulative production and profits for 25 years [1].
Oil palm flowering plays an important role in the formation of fresh fruit bunches.The type of flowering in oil palm is known as the monoceaus type, which means that in one tree there are male and female flowers but are located in different bunches [3].The anthesis period of male and female flowers 2 rarely coincides, so the pollination process is highly dependent on pollinating agents such as wind and insects [4].In addition to pollinating agents, plant material also determines pollination success.[3] stated that there was a difference in the flowering phenology of the DxP Socfindo MT Gano and DxP 540 NG varieties, the average number of male spikelets for the DxP Socfindo MT Gano variety was 93 bunches - 1 and for the DxP 540 NG variety 103 bunches -1 , the female flower spikelets of the variety DxP Socfindo MT Gano is 104 bunches -1 and on DxP 540 NG, it is 108 bunches -1 .The average number of male flower buds on each spikelet on the DxP Socfindo MT Gano variety was 668 bunch -1 and on the female flower was 11 bunch -1 , while on the DxP 540 NG variety, the average number of male flower buds was 674 bunch -1 , and on the female flower 9 bunches -1 .The duration of the flowering period for the two varieties is also different, the male flowers on the DxP Socfindo MT Gano variety take 63 days and the female flowers 66 days while the male flowers on the DxP 540 NG variety take longer, namely 71 days and on the female flowers 78 days [3].
It is necessary to know the number of male and female flowers produced by oil palm to determine the value of the sex ratio.The sex ratio value is obtained from the ratio of the number of female flowers to all the flowers produced, this value is information on the availability of pollen needed to pollinate the female flower bunches.Feminine phenomena or more female flowers than male flowers in optimal environmental conditions have recently occurred, and of course, this is a problem in achieving production because the sex ratio affects the number of bunches harvested [5].Furthermore, the fruit set which is the ratio between finished fruit (developing due to pollination) to the number of all fruits in one intact bunch (including parthenocarpy/mantle fruit) affects the average length, the greater the furit set value, the average length increases. .The fruit set value can be said to be good if the percentage is > 75% [6].The implication of the fruit set value concerning the fruit to bunch value is that the greater the fruit set value, the fruit to bunch value will increase [4].
Knowing the value of sex ratio, fruit set, and fruit to bunch of DxP Socfindo MT Gano oil palm varieties in TM 1, TM 2, and TM 3 is vital.This research was done to know the value of sex ratio, fruit set, and fruit to bunch.

Research Method
The research was conducted at the Bangun Bandar Estate, PT.Socfin Indonesia from December to February 2022.The research implementation is described in the following sub-chapters:

Research Sites
The Bangun Bandar Estate are located in the Dolok Masihul sub-district, Serdang Bedagai Regency, North Sumatra province.The topography of the land in Bangun Bandar Estate is flat to undulating and located at an altitude of 0 -50 m above sea level.The Bangun Bandar Estate is bordered by the town of Dolok Masihul to the north, to the south by the village of Bukit Cermin, to the east by Kampung Bantan, and to the west by Silau Dunia Estate.The area of the statement of Bangun Bandar Estate is 4,178.79ha, which is divided into 4 divisions with respective areas respectively 1,185.14 ha, 977.92 ha, 988.72 ha, 508.93 ha, and 1,027.01ha.

Research Design
The study used a survey method, as the treatment was the planting year (plant age) which consisted of 3 namely the 2019 planting year (3 years old), the 2018 planting year (4 years old), and the 2017 planting year (5 years old), varieties DxP Socfindo MT Gano.From each plant age, 6 fresh fruit bunches (FFB) samples were taken, and each treatment had 5 replications so that 90 FFB samples were obtained to be observed.

Research Stages
The research was carried out in the following stages: 2.3.1.Determine research plots and sample plants.The research plots were chosen in blocks with populations of at least 100 plants in one hectares that were not receiving special treatment, such as fertilization therapy or treatment owing to pest or disease attacks.Fruiting sample plants had mature fruit that met the requirements for a ripe harvest and wasn't implanted plants, and discs in pristine condition were chosen.

Management of samples of fresh fruit bunches.
For the FFB that has been collected, the bunches are cut to resemble a "V" shape or like the frog's gaping mouth, each sample is weighed along with the loose fruit, and the spikelet is cut into three parts, namely the base, middle, and tip.The number of spikelets is counted, from each part of the spikelet, 20% is taken from the total spikelet.Next, the number of flowers and fruit is calculated for the spikelet sample taken (fruit set value).The loose fruit is separated from the spikelet, which aims to separate the stalk, loose fruit, and bunch waste.The loose fruit is sieved clean, and the loose fruit for each bunch is weighed.Next, the stalk, loose fruit, spikelet, and bunch of waste were weighed.The data is used to calculate fruit to bunch.

Data collection and analysis.
Observational data is arranged in tables of variance, analyzed by Analysis of Variance (ANOVA) at a 5% level, if the calculated F value > F table, then proceed with the Duncan Multiple Range Test (DMRT).

Analysis of bunch and stalk weight
Rainfall is a climate element that plays an important role in the formation of flowers and fresh fruit bunches of oil palm.Oil palm require rainfall of 2,000-2,500 mm year -1 which is evenly distributed throughout the year.To find out the distribution of rain in the Bangun Bandar plantation is presented in Figure 1.In a period of 5 years, from 2017 to 2021, it can be seen from the data that the annual water needs of the oil palm are met by the rain falls on the Bangun Bandar plantation.This indicates that the development of oil palm flower and fruit formation is not hampered by rainwater.In line with [7] the process of forming and developing flowers in oil palm plants is greatly influenced by the availability of water.Generally during the rainy season, more female flowers are formed than male flowers.While in the dry season, the opposite happens.Adequacy of water, proper nutrition, and environment will support the formation of male and female flowers perfectly.Based on statistical analysis, the weight of fresh fruit bunches on MP1, MP2, and MP3 of the DxP Socfindo MT Gano variety showed significant differences.The average weight of FFB in MP3 is greater than the FFB in MP1 and MP2, as shown in Figure 2. In oil palm bunches there is a stalk at the end of the bunch, in this study the diameter and weight of the stalk were measured manually.The average stalk diameter and weight are listed in Figure 2. Based on the analysis of variance, the stalk diameters in MP1, MP2, and MP3 were significantly different, but not significantly different in the measurement of stalk weight.The diameter of the stalk in MP3 is larger than in MP2 and MP1, this is related to the increasing age of the plant, the larger the diameter of the stalk.

Analysis of oil palm bunches' physical quality
The physical quality of oil palm bunches can be seen from several components, namely the number of spikelets, the number of finished fruit + parthenocarpy fruit, the average number of parthenocarpy fruit per spikelet, the average finished fruit per spikelet and the percentage of finished fruit per spikelet.The average observation results are listed in Table 1.The results of the analysis of variance showed that the number of spikelets, the number of finished fruit and parthenocarpy fruit, and the number of finished fruit per spikelet were significantly different between MP1, MP2, and MP3.The highest number of spikelets is found in MP3.The number of parthenocarpy pods per spikelet was significantly different between MP3 and MP1 and MP2.Meanwhile, the percentage of finished fruit in MP1, MP2, and MP showed no significant difference.As the age of the plant increases, the number of spikelets increases.Finished fruit is characterized by the presence of a fruit core which is the end result of pollen mating from male flowers with egg cells in the female oil palm flower, whereas parthenocarpic fruit does not have a fruit core (kernel).Although sometimes parthenocarpic fruits with thick flesh but no kernels are found, the amount is less than 0.1% per bunch.[8]

Sex ratio
The sex ratio in MP1 is significantly different from MP2 and MP3, the highest sex ratio is found in MP1, which is 92.77%.A high sex ratio indicates the number of female flowers, young plants tend to have a high sex ratio, which is > 80%.A high sex ratio does not guarantee high oil palm productivity, because the female flowers that are formed may not all become fruit bunches that can be harvested.Abortion of female flowers is still possible if the plants experience water deficit, over-pruning, and lack of carbohydrates [7].

Figure 3. Sex ratio
In this study, the sex ratio was calculated manually, by calculating the anthesis interest for each oil palm tree [9].The value of the sex ratio based on observations of anthesis flowers in the field is presented in Table 2.
The results of the analysis of variance showed that anthesis female flowers, anthesis male flowers, the number of male and female flowers anthesis, sex ratio, and the percentage of male flowers and female flowers anthesis per hectare were significantly different between MP1, MP2, and MP3.All variables in the observation of oil palm flowering showed a positive trend, as the age of the plant increased, the number of male and female flowers of anthesis also increased.This was followed by the value of the sex ratio which decreased with the increasing age of the plant.

Fruit set
Oil palm productivity is closely related to fruit set value.A fruit set is an arrangement of fruit in fresh fruit bunches which depicts fruitfulness.Fruit set analysis aims to determine the percentage of female flowers that become perfect fruit in one fresh fruit bunch.The value of good fruit set in oil palm plants is > 75% [10].Abnormal fruit, namely parthenocarpy fruit, and infertile fruit.This can be caused by pests and diseases such as the Tirathaba rufivena pest which can occur at every stage of oil palm flower and fruit development [11].Apart from pest attacks, abnormal fruit can also occur due to pinched fronds.

Figure 4. Fuit set in MP1, MP2 and MP3
The results of the analysis of variance showed that the number of finished fruit and fruit set was not significantly different in MP1, MP2, and MP3 while the parthenocarpic fruit in MP1 and MP2 was significantly different from MP3.The value of the fruit set MP1, MP2, and MP3 of the DxP Socfindo MT Gano variety is 69-73%.That is, the content of normal loose fruit to total loose fruit is 69-73%.The value of this fruit set can still be increased, by optimizing the E. kamerunicus population so that it is not less than the minimum amount that must be available in the field.This is emphasized [8] even though the E. kamerunicus population has reached 44,935 ha -1 , the fruit set value is only 62%, thus for the fruit set to reach 75%, the E. kamerunicus population needs to be increased to 144,645 ha -1 and male flowers available as many as 9 flowers ha -1 .
An increase in fruit set will result in a moderate correlation to the increase in fresh fruit bunch weight with a correlation value of 0.498.The higher the value of the fruit set, the weight, quality, and size of the bunches will increase.The percentage of kernel/bunch, fruit/bunch mesocarp, or oil/bunch will also increase [12].

Fruit to bunch
Fruit to bunch is the ratio of fruit weight to bunch weight, the higher the fruit to bunch value indicates the heavier the fruit weight.Analysis of variance showed that the finished fruit weight, bunch weight, and fruit to bunch were significantly different between MP1, MP2, and MP3.As the age of the plant increases, the fruit weight, bunch weight, and fruit to bunch increase.The correlation between fruit set and fruit to bunch at TM 1, TM 2, and TM 3 shows a positive correlation.The high fruit set will produce a very strong correlation effect on the fruit to bunch value with a correlation value of 0.871.
3.6.Implementation of the management of sex ratio, fruit set, and fruit to bunch 3.6.1.Sex ratio.Young plants generally have a high sex ratio, which causes a low fruit set.To produce an ideal sex ratio in young plants of the DxP MT Gano variety, it is necessary to take actions such as planting plant varieties that produce more male flowers such as super male, stressing plants to increase male flowers, so increasing the effectiveness of pollination.Artificial pollination (assisted pollination) is the most effective step to increase fruit set up to 70%.Low fruit set occurs due to the very small population of oil palm pollinating insects, especially E. kamerunicus, that they are unable to pollinate all the female flowers.If this happens, what can be done is assisted pollination for a while waiting for the development of E. kamerunicus.The hatch & carry technique has been applied in several orchards in Indonesia and has succeeded in increasing the initial fruit set.This technique is generally performed on TM 1-3 which has a low fruit set value and a very high-interest sex ratio [13].

Fruit set.
To produce a high fruit set with a high sex ratio value in young plants, it is necessary to carry out actions such as selective castration by leaving male flowers in the last 4-5 castrations, assisted pollination, hatch and carry, stressing plants to increase male flowers and prevent a reduction in insect populations.pollinator (E.kamerunicus).The decline in E. kamerunicus populations can be influenced by insecticides or plant pest control applied in oil palm plantations in general which are E. kamerunicus poisons.The effect of decreasing the population of E. kamerunicus can occur because the spraying process will directly affect the body of the beetle 34 or be absorbed into the flowers and the larvae of E. kamerunicus and result in death for adults and larvae contaminated with the pesticides applied [8] 3.6.3.Fruit to bunch.Fruit to bunch is greatly influenced by the number of fruits per spikelet and the weight per fruit, these two things have the potential to produce a high oil content.Obtaining high oil can be done by optimizing plant maintenance (fertilization), shoot management, weed control, and proper extraction of production potential (harvest).The crocodile grafting method can be implemented by plantation that experience a low percentage of fruit set to improve the quality of bunches, namely the percentage of fruit to bunch.The percentage of fruit to bunch with crocodile graft treatment was higher than that of frog graft with an average difference of 6%.

Conclusion
In general, the DxP Socfindo MT Gano variety mature plant (MP1, MP2, MP3) has a high sex ratio and low fruit set.However, as the plant ages, the value of fruit set and fruit to bunch also increases.Therefore, optimizing plant maintenance such as meeting nutrient and water needs, proper budding, and considering the population of E Kamerunicus pollinating agents must be carried out.All these actions are needed hence the process of formation and development of flowers, as well as the process of pollination and the formation of fresh fruit bunches of oil palm runs well.

Figure 2 .
Figure 2. The average weight of FFB, diameters, and weight of stalk

Table 1 .
Analysis of oil palm bunches' physical quality

Table 2 .
Flower composition and sex ratio in MP1, MP2 dan MP3