Introduction. Mangosteen (Garcinia mangostana) is a tropical fruit that isfamous for its edible pulp. This edible pulp makes up only 30% of the total fruit, whilethe remaining pericarp and seed are regarded as waste. Facing the increasing public demandfor naturally safe foods and products, our study aimed to elucidate the antioxidantcapacity and antibacterial activity of different parts of mangosteen, including thepericarp, pulp and seed. Materials and methods. The antioxidant capacities ofmangosteen’s pericarp, pulp and seed extracts were determined using the ferric reducingantioxidant power (FRAP) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, whereasantibacterial activity was determined using the disc diffusion method.Results. The pericarp extract exhibited higher antioxidant capacities thanthose of pulp and seed extracts, with a Trolox equivalent antioxidant capacity (TEAC)value of 122.00 µM·g–1 and ferrous sulphate equivalent antioxidant capacity (FEAC) valueof 18.99 mM·g–1. All mangosteen extracts showed strong inhibition against Staphylococcus aureus ATCC11632, while only the pericarp extract was effectiveagainst Bacillus cereus ATCC10876. No inhibition againstEscherichia coli ATCC10536 was observed. Conclusion. Theoutcomes of our study could facilitate future application of mangosteen waste as abiopreservative in the food industry.

Introduction. In Malaysia, Limau Madu (Citrusreticulata Blanco; Citrus suhuiensis Hort.ex Tanaka) is commercially cultivated for local consumption. Itis a loose-peel mandarin with fruits that are spherical in shapewith shiny green or greenish yellow peel. In Malaysia, Limau Maduis vegetatively propagated, thus it is presumed to exhibit minimalvariability. In our study, the genetic variability and genetic relatednessamong cultivated samples collected from different states in Malaysiawere assessed using Simple Sequence Repeat (SSR) primers. Materialsand methods. Thirty pairs of SSR primers derived from Citrusunshiu were screened and 22 SSR primer pairs were utilizedto assess genetic variability and relatedness among 118 cultivatedsamples. Results and discussion. The percentage of SSR transferabilityfrom C. unshiu to C. reticulata (LimauMadu) was 73.33%, which indicated that the primer sequences flankingsimple sequence repeats were conserved among these Citrus species.Most SSR loci revealed a large excess of heterozygotes. In our study,low allelic diversity was shown, with an average of 5.227 allelesper locus. Polymorphic information content (PIC) ranged from 0.048to 0.674. Based on UPGMA clustering analysis, four groups were identifiedfrom these citrus genotypes with a mean genetic distance of 0.170. Lowgenetic variability within species was probably due to vegetativepropagation or inability to detect differences among samples usingthese primers.

Introduction. Dabai (Canarium odontophyllum Miq.) fruit is an underutilized fruit found in Borneo, Palawan and Sumatra. To our knowledge, no literature exists about the postharvest quality characteristics of dabai fruit. Furthermore, it is a unique fruit whereby the fruit is served by steeping at about 60 °C for 15–20 min to soften the flesh. Therefore, a preliminary study was conducted to determine the physicochemical characteristics of dabai fruit before and after steeping. Materials and methods. Physicochemical characteristics (skin color, size, shape, weight, mesocarp thickness, firmness, soluble solids concentration, pH, titratable acidity, organic acids, respiration production rate and ethylene concentration) of dabai fruit were determined before and after steeping in hot water at 60 °C for 15 min. Results. The color of mature dabai fruit is dark purplish with very low chromaticity. The fruit is oval-shaped with a length to diameter ratio of 1.40. The seed contributes 61% of the fruit weight. After treating fresh dabai fruit with 10 mL·L-1 ethylene at 20 °C, the respiration production rate decreased while ethylene concentration increased. After steeping dabai fruit at 60 °C for 15 min, the flesh firmness decreased while soluble solids concentration increased tremendously. After steeping, the pH of fruit decreased and titratable acidity increased, as did the citric, malic and succinic acids of dabai fruit, especially citric acid. Conclusion. Steeping softens dabai fruit flesh and makes it palatable, with high soluble solids concentration and organic acids. The high respiration production rate means that dabai fruit has a short shelf life under non-cold chain handling practices.

Introduction. Pulasan and lychee are from the same family and closely related, therefore the SSR markers are expected to be highly transferable between these two taxa. We investigated the transferability of 12 lychee (Litchi chinensis Sonn.) simple sequence repeat (SSR) loci to pulasan (Nephelium ramboutan-ake L.). Materials and methods. Genomic DNA was extracted from 20 accessions of pulasan for the PCR amplification of the SSR loci using 12 pairs of SSR primers derived from lychee. The PCR products were resolved on denaturing polyacrylamide gels. Results. The percentage of SSR transferability from lychee to pulasan was 58.3% and the percentage of polymorphic SSR markers was 25%. Discussion. The moderate transferability and low polymorphism rates suggest the possibility of interruptions within the repeat motif and mutations in the flanking sequences of SSR repeat motifs. Our results did not reveal a high rate of transferability between lychee and pulasan. However, this study showed that the SSR markers developed in lychee are a good source of molecular markers for pulasan.

Introduction. Rhizobacterial inoculation in low fertilizer-N conditions, viz., 33% fertilizer-N of the total N requirement, could produce similar plant growth to the 100% N-fertilization of banana plantlets grown under hydroponic conditions. Thus, we tested PGPR inoculation in combination with fertilizer-N application to study the role played by strains of rhizobacteria in nutrient accumulation, nitrogen fixation and, consequently, improvement in yield and fruit quality of bananas. Materials and methods. Two PGPR strains were used in the experiments, namely, Sp7 (Azospirillum brasilense) and UPMB10 (Bacillus sphaericus). The design of the experiment was completely randomized with three replications. Eight treatments were applied: control without fertilizer-N application (N0%) and without PGPR; N0% + Sp7; N0% + UPMB10; N33% without PGPR; N33% + Sp7; N33% + UPMB10; N100% without PGPR and N100% + UPMB10. One tissue-cultured banana (cv. ‘Berangan’) plantlet was planted in a plastic pot (4 L) for 45 days and thereafter transferred to a larger polyethylene tank (1000 L) until maturity. A 100-mL broth culture of Sp7 or UPMB10 was added to the respective tanks after the transplanting process and repeat inoculations were performed monthly. The fruits were harvested at the maturity stage after 80–90 days of flowering. After ripening, yield and fruit quality parameters were assessed. Results. Inoculation with 33% fertilizer-N increased the total nutrient accumulation (N, P, K, Ca and Mg). PGPR inoculation along with 33% fertilizer-N significantly increased the bunch yield and fruit physical attributes, namely, finger weight, length and diameter, and [pulp / peel] ratio, besides inducing early flowering by 3 weeks. Conclusion. The results suggested that PGPR strains Sp7 and UPMB10 could be used as bioenhancer and biofertilizer for early, high-yielding and improved banana fruit production in 33% fertilizer-N conditions.

Introduction. The isolation of humic acid (Ha) from decomposed organic substances such as compost is time-consuming, as it takes not less than 24 h. We investigated whether the isolation time of Ha produced from composted pineapple leaves could be reduced. Materials and methods. Ha from 10 g of pineapple compost was extracted with 100 mL of 0.10 M NaOH. Different extraction times [(4, 8, 12, 16, 20 and 24) h] were tested. At the end of each time, the samples were centrifuged. The dark-colored supernatant liquor containing Ha was decanted and filtered; the pH of the solution was adjusted to 1.0. After acidification, the fractionation times tested were (3, 6, 9, 12, 15, 18, 21 and 24) h. At the end of each fractionation time, the supernatant liquor (fulvic acid) was siphoned off from the acidified extract. The remainder of the suspension was transferred to a polyethylene bottle. Ha was purified by suspending it in 50 mL distilled water, then centrifuged, and the supernatant was decanted. After repeating this procedure five times, the supernatant and the fulvic acid were analyzed for Ca, K, Mg, Mn, Na, Cu, Fe and Zn. The washed Ha was oven dried at 30 °C to a constant weight and the Ha samples were analyzed for ash and mineral matter. Results and discussion. The ash content was not more than 1%, the generally acceptable maximum value. The mineral contents decreased in Ha samples with washing. The yield of Ha significantly increased with increasing extraction time, except for the (20 and 24) h extraction times, which did not show statistically different Ha yield, meaning that the exchange sites of Ha of the pineapple compost might have been saturated with Na ions from 20 h. There was no significant difference among the fractionation times, indicating that Ha of the pineapple compost requires about 3 h to equilibrate or stand immediately after acidification for the H ions to replace the Na and the other cations. There was no significant interaction between the factors extraction and fractionation. Conclusion. The isolation of humic acids from composted pineapple leaves can be achieved with an extraction time of 20 h and a fractionation time of 3 h.

Introduction. Their physical and chemical properties make sandy tin tailings unsuitable for agricultural purposes without proper fertilizer and crop management practices. An attempt was made to use these tailings for sustainable production of pineapple using fertilization and irrigation techniques. Therefore, the objective of the study was to determine the effect of ground sucker size and levels of fertilizer used on yield and nutrient accumulation in plant components of pineapple cv. Josapine grown on sandy tin tailings. Materials and methods. Three fertilizer levels (plot 1, plot 2 and plot 3) containing N, P, K, Ca, Mg and Cu in solution and three classes of ground suckers (> 70 cm, 70–40 cm and < 70 cm) were used. They were arranged in a randomized complete block design with three replicates. There were 32 plants in each experimental plot. Each plot received a similar quantity of Fe, B, Mn, Zn and Mo. At harvest, each plant’s parts were divided into fruit, leaves, stem and roots. The dry matter yield and nutrient contents of each pineapple part were analyzed and recorded. Results and discussion. The highest and the lowest amounts of dry matter were 397 g·plant–1 (size > 70 cm) and 96 g·plant–1 (size < 70 cm), respectively. Total dry matter accumulation was greater (26%) for plot 1 than for plots 2 and 3. Substantial amounts of the dry matter accumulation occurred in leaves (45.0%) and fruit (34.0%) and less in stems (16.0%) and roots (5%). A similar pattern was also observed for the total (major and micro-) nutrient accumulation in the plant components. Besides the fruit parameters, the length of the pineapple stem is an important factor affecting the yield of pineapple, either expressed on a fresh (R2 = 0.904***) or dry (R2 = 0.855***) weight basis. Conclusion. Ground sucker size is a very important factor for successful production of a high fruit yield and quality of pineapple planted on sandy tin tailings.

Introduction. One of the challenges of the Malaysian pineapple industry is to develop new techniques for managing pineapple residues. A study was carried out to investi- gate whether K-humate can be produced from these residues. Materials and methods. Pineapple leaves were air-dried, shredded and chipped. Some of the shredded leaves were incinerated at 500 °C. Potassium hydroxide (KOH) was extracted by dissolving the ash obtai- ned in distilled water for 24 h at a ratio of 1:7 (ash / water) after which the sample was filte- red. After this extraction of KOH from the ashes of pineapple leaf residues, the remaining ash residues were further analyzed to assess the total and soluble K contents. Moreover, a given quantity of shredded leaf residues was mixed with chicken dung (as a source of microorga- nisms and nitrogen) and chicken feed. The mixture was composted with standard procedu- res. Humic acids were reconstituted using KOH from pineapple leaves with K from ash residues and K from composted pineapple leaves. Results and discussion. By reconstituting humic acids with KOH, a K-humate was produced with approximately 34.5% of its K readily soluble in water. A reconstitution of humic acids with K from ash residues produced a K-humate with approximately 3.34% of its K readily soluble in water. Conclusion. The K-humate produced from the reconstitution of humic acids with K from KOH can be used in fertigation programmes as a source of K while the K-humate produced through the reconsti- tution of humic acids with K from ash residues can be used as a source of K for fresh water fishes.

Introduction. Two field experiments were conducted to investigate the effects ofpotassium (K) on plant growth, fruit yield and quality of pineapple cultivated on tropical peat soil.Materials and methods. Six levels of K: 0, 266, 532, 798, 1064 and 1330 kg $\cdot$ ha-1 K2Owere applied at each of two pineapple plantations located at two different sites. The experiments wereconducted with the Gandul cv. in a randomized complete block design with three replications. Results anddiscussion. The application of K had not any significant effect on plant height and leaf number ofpineapple at both sites. Potassium significantly influenced the fruit diameter at site 1, and fruit lengthand fruit weight at site 2. The application of 266 kg $\cdot$ ha-1 K2O resulted in the highest fruitweight and, at site 2, further increase of K declined it. Potassium had no significant effect on fruitsugar and acidity. However, at site 2, acid content tended to increase with increased K applications.Conclusion. Potassium applications at high rates tended to depress most of the growth and yieldattributes of cv. Gandul pineapple cultivated on peat soil in Malaysia.