Fruit Description and Evaluation of Five Treatments to Break Seed Dormancy of Brownlowia peltata Benth

Brownlowia peltata Benth. is a native tree from Borneo, in its germination problemwas physical dormancy due to the hard pericarp of the fruit. The study aimed to evaluate five treatments for breaking the seed physical dormancy and the fruit description. The experiment was using Randomized Complete Block Design (RCBD) with four different temperatures of water immersion, a scarification, and control. The fruit of B. peltata was a woody follicle; belong to yellow green group 148 A in color; 29.64 mm in long; 21.62 mm in thickness; 29.86 mm in wide, with an average weight of 12.05 g. Hot water immersion treatment of 40∘C for 60 s; 60∘C for 60 s and 80 ∘C for 30 s could raise the fruit moisture content of 0.92% to 1.04%. There was a significant difference on germination rate coefficient and coefficient of uniformity of germination among treatments. The mature seed does not have a physical dormancy once the carpel splits and create a slit (fruit opening).


Introduction
Here Brownlowia belongs to Tiliaceae family and currently according to APG III, along with Bombacaceae, Malvaceae and Sterculiaceae merge into Malvaceae.Brownlowia peltata Benth. of the subfamily Brownlowioideae, is a small tree which is native to Borneo.The wood has been used for furniture and housewares.The fruit or seed is eaten as fresh fruit and used as a source of oil for perfumery by locals [1].
Brownlowia peltata is mainly propagated by seed since it produces a lot of fruit in recemes.Brownlowia's fruit is woody follicle with rough hard pericarp.However, hard seed pericarp of the fruit may cause slow and erratic germination and emergence.We expected this hard pericarp was water-impermeable which causing physical dormancy (PY) in the seed germination.Physical dormancy occurs due to the cover of fruit and seed with hard water permeability.It may well be, due to the presence of woody walls of fruits or seeds [2].The result of a study by Bien & Lan [4] recommended that seeds of B. tubularis need sowing immediately after harvest and was treated with 60 ∘ C water immersion for an hour before sowing.It indicated that B. tubularis possibly had a physical dormancy that needs to break before sowing.
Two specimens of B. peltata which are cultivated in Bogor Botanic Garden are flowering twice a year and produce abundant of fruits.The seedlings that are growing naturally from seed have never been observed related to the seed characters and dormancy.The germination character of B. peltata is also poor known.Therefore, the aim of this study was to evaluate five treatments to break the physical dormancy of the seed along with the fruit description.

Materials and methods
More than 240 fruits of Brownlowia peltata Benth.were collected from a collection specimen of Bogor Botanic Garden at May 4th, 2015.The fruit age or maturity was unknown and indehiscent (not split yet).The fruit and seed examination were conducted in Treub Laboratory and Seed Bank Unit of Bogor BG.The observation of germination conducted in trial nursery of Bank Seed Unit from May to June 2015.In fruit and seed description examination, we used 30 fruits that were chosen randomly.The variables included weight of 1000 units, fruit color (using RHS color chart), dimension size of fruit and seed.
For germination test, we used a Randomized Complete Block Design (RCBD) with total six treatments for breaking physical dormancy: four different temperatures of water immersion, a scarification treatment, and a control.Each treatment had four replicates and each replication contained 10 fruit.The water temperatures were 40 ∘ C for 60 min; 60 ∘ C for 60 min; 80 ∘ C for 30 min; and 93 ∘ C for 1 min.After the fruit had got treatments, all of the seed were immersed in room temperature water for 24 h to encourage imbibition.Sowing of the seeds conducted in boxes of sand media under tree shade with regular watering.Environment data was also collected throughout the observation including temperature, relative humidity, and light intensity.

Data analysis
Calculation of the seeds moisture contents on fruit was using formulas below: Calculation of germinating rate was using formulas as follows [5]: Germination rate = number of seeds germinated number of seeds on tray × 100% (2) Coefficient of uniformnity of germination = ∑  ∑{( − ) 2 Descriptions: : × day; : number of seed;  : Total number of days of germination.
Data analysis used Fisher Test (F-test) at a real level 0.05, followed with Duncan Multiple Range Test at a real level 0.05, when the F-test showed significant different.

Fruit and seed descriptions
Based on the examination, the fruit of B. peltata belongs to follicle type, oval, slightly flattened, sometimes irregular, woody with a line of dehiscence dividing the carpel into two parts.It contained a single seed that at maturity the fruits dry and dehisces on the line of dehiscence into two carpels [6], but in this case, the seed did not release and was separated from carpel.The carpel was persistent until the seed germinating.
The seed husk (pericarp) consists of three layers, the outer layer (exocarp) was hard woody layer with gray-brown pubescent hair/scales; brownish green (yellow-green group-148 A-B) in color.The mesocarp was a thick woody fibrous layer.The endocarp represented the seed coat; thin and water-impermeable [7].It had length of 2.96 cm ± 0.27 cm; width of 2.99 cm ± 0.25 cm; thickness of 2.16 cm ± 0.22 cm.The weight of 1 000 seeds was 11 342.39 g.The seed was off-white (ivory); flattened heart-shaped with the embryo was on the tip; 1.93 × 1.81 cm.Cotyledon was 0.49 cm × 0.22 cm (see Figure 1).

Imbibition rate
Germination starts with imbibition, a process of water uptake of seed, caused by different water concentration gradient between seed and the environment.It changes the metabolic process of the seed and induces cell differentiation of the embryo.The more water that goes into the seed, the colloidal materials such as proteins are likely inflated and causing the split of seed husk.
The fruit weight was 11.74 g when collected with moisture content of 63.54%.Volume of fruit changed after the treatments and 24 h imbibition.Figure 2 shows percentage of the change of fruit weight before-after treatment and after 24 h imbibition.
B. peltata fruit was floating at the beginning of water immersion due to its fibrous seed husk.After imbibition, some of the fruits were still floating and some of them were sunk.Hot water immersion treatment of 40 ∘ C for 60 s; 60 ∘ C for 60 s and 80 C for 30 s raised the fruit moisture content of 0.92% to 1.04% which is similar each other, husk became more brownish and blackened.Figure 3 shows the discoloration of the outer husk after hot water immersion treatments.
After 24 h imbibitions, the highest imbibitions rate occurred to the scarification treatment (71.19%) and the lowest imbibitions rate occurred to control (68.07%).Comparing among hot water immersion treatments, the treatment of 80 ∘ C for 30 led the highest imbibition rate of 69.37% while the other treatments of 40 ∘ C for 60 s, 60 ∘ C for 60 s and 93 ∘ C for 1 s led relatively similar imbibition rate.They are 68.35%,68.31% and 68.40%.Scarification treatment affected the water uptake of the seed before sowing.
It indicated that the outer pericarp was impermeable.High temperature (up to 93 ∘ C) was not effective enough to break the permeability of the pericarp.

Seed germination
Germination is influenced by some of the factors, either internal or external.The main external factor are water, oxygen, and temperature [8].Germination type of B. peltata seed was epigeal.Primary root or radicle was the first part growing from the seed, followed by elongation of hypocotyl that lifted up the cotyledon and plumule.Sometimes the carpel persisted to the cotyledon and lifted up along with it [9].Splitting of the carpel was a sign that cotyledon and embryo cell were swollen and developing because of sustainable water uptake.It happened DOI 10.18502/kls.v3i4.686mostly on the day 12 after sowing.After hypocotyl had stopped growing, the plumule was growing bigger became two opposite leaves along with epicotyl.The cotyledon shrank gradually after the plumule reaches the maximum size and started a new shoot.
After the plumule reaches this maximum condition, we assumed that the germination was complete.It happened on the day 35 after sowing.Figure 4 shows the germination stage of B. peltata.
Either scarification or low-temperature treatment (40 ∘ C) did not raises germination rate significantly compared to control.The high temperature of water immersion treatment (80 ∘ C or more) had a tendency of damaging the seed instead of breaking the dormancy.According to germination rate coefficient, it showed that scarification treatment had the highest value (0.1558) compared to other treatment, but Duncan Multiple Range Test (DMRT) 0.05 results (Table 1) showed that scarification treatment and 60 ∘ C water immersion treatment was insignificant compared to control.Analysis of coefficient of uniformity of germination led to different result.The highest value was obtained by scarification treatment which means the treatment produced the most uniform germination of the seed among others.However, since it was not significantly different to control and 60 ∘ C treatment, we believe that those five treatments did not raise the uniformity of germination of the seed.
Fabaceae, Malvaceae s. lat.(including Bombacaceae s. str., Sterculiaceae s. str.and Tiliaceae s. str.), and Rhamnaceae has been confirmed as and Peer-review under the responsibility of the ICBS Conference Committee.ICBS Conference Proceedings families of PY [3].They mentioned seeds of Luehea speciosa, Luehea seemannii, Apeiba aspera, Apeiba tibourbou (Tiliaceae s. str.) were assigned to dormancy class PY.Mechanical scarification, chemical (acid) and immersion in hot water/ heat treatment are two popular treatments to open the seed wall or break physical dormancy.

Figure 2 :
Figure 2: Imbibition rate of B. peltata fruit after treatments and 24 hours imbibition.

Figure 3 :
Figure 3: The discoloration of Brownlowia peltata fruit after hot water immersion treatments.
Outdoor temperature at the location of germination test was 23 ∘ C to 31.7 ∘ C in the morning and 31.4 ∘ C to 34.8 ∘ C in the afternoon.The containers was placed under canopy shade of Durio zibethinus, Cinnamomum burmannii, and a palm to imitate natural condition in forest.Humidity of germination media was maintenance by regular watering.