The assessment of genetic diversity is essential for the conservation and breeding purposes. This study aimed to assess and evaluate the genetic diversity of 116 accessions of mango (Mangifera indica) germplasm using microsatellite markers. The DNA was extracted from young fresh leaf before genotyping using microsatellites to determine the allele size. The analysis of 20 polymorphic microsatellite markers revealed a total of 122 alleles ranging from two (MiIIHR10, MiIIHR21, and MiIIHR25) to 11 alleles per locus (MiIIHR28 and MiIIHR30) with an average of 6.1. The mean polymorphic information content (PIC) value was 0.4585 which ranged between 0.0081 (MiIIHR10) to 0.9573 (MiIIHR28). The UPGMA dendrogram indicated that the accessions were divided into two major clusters, which were divided into several sub-clusters based on their genetic distance matrix values. Some accessions were highly similar to each other, probably due to the duplication of collected accessions or insufficient microsatellite markers to differentiate them. The analysis of the population structure of the individuals also showed two subpopulations, suggesting that the accessions could be separated into two groups, which supported the generated dendrogram. The findings of this study facilitate improved conservation management of the germplasm and help to find strategies for future breeding activities.

Magnifera indica cv. Harumanis is one of the most commercially grown mango cultivar in Malaysia due to market demand and price. However, the fruit supply never meets the demand as Harumanis is highly sensitive towards the climate and only grows in Perlis and part of Kedah. Crop productivity and development are mainly related to climatic variables where temperature and precipitation are the most importance. Temperature and precipitation distribution pattern affect flowering, fruit set, fruit growth and also fruit development. This study evaluates the relationship between temperature and precipittaion distribution pattern towards development of Harumanis growth stages including flowering and fruit development aspects in Zone 1 (area with a clear dry season up to three or four months) and Zone 2 (area with a clear dry season between one to two months). Thermal calendar based on daily and accumulated growing degree days (GDD) used to predict growth stages. Results indicate that Harumanis need a hot and dry environment (high temperature with less precipitation) during reproductive stage. However, there is no significant difference between Zone 1 and Zone 2 on the GDD required during every growth stages. On yield and fruit quality aspects, Zone 1 produced higher yield and better quality than Zone 2 due to the environmental factor even though there is no significant difference. Future study needs to be done as this information together with projection of future climate change scenarios are crucial in developing Decision Support Tool (DST) to guide the farmers in planning their crop management practices for the upcoming season.

There is an increase in demand for high-quality rock melon for the local market. Supplementing salt with a nutrient solution is a viable approach that can be implemented to improve fruit quality. Therefore, this study aims to determine the best salt treatment that can be utilized to increase fruit quality without reducing growth, yield, and physiological process. The study is conducted by grafting (DAG) rock melon/bottle gourd at 18 days with four sources of salinity: basic nutrient solution (BNS) (2.5 dS m-1), sodium chloride (NaCl) (50 mM) + BNS (7.1 dS m-1), potassium nitrate (KNO3) (50 mM) + BNS (7.1 dS m-1), and high strength nutrient solution (NS) (7.1 dS m-1). The plants were arranged in a randomized complete block design (RCBD) with four replications. Salinity induced using KNO3 + BNS sustained most growth variables, fruit quality, relative water content, and leaf gas exchange compared with control. However, applying NaCl + BNS and high strength NS could sustain all physiological processes and increase fruit quality components, such as total soluble solid and sugar-acid ratio compared to control. Fruit weight had reduced regardless of salinity sources than those grown in control with their respective fruit weight reduction of 28.8%, 28.26%, and 27.72%. To conclude, incorporating NaCl at 50 mM is the most feasible approach to be applied on grafted rock melon/bottle gourd even though the fruit weight had reduced. It is due to the high fruit quality measured, capable of sustaining all physiological processes, provides lower cost, and is easily accessible than other sources of salinity.

Identification of zygotic and nucellar seedlings of Harumanis mango by morphological approach is impossible or hard to be performed. Therefore, this research were to identify zygotic or nucellar seedlings from Harumanis mango polyembryonic seeds through simple sequence repeat (SSR) molecular markers in relation with germination sequence and vigour of seedlings for source of true-totype cutting material. The results showed that there were 3 seedlings per seed on average. The result from the molecular analysis of 136 seedlings (45 seeds) showed four zygotic seedlings in seeds 1, 15, 29 and 43 representing 8.9% of seeds evaluated. Most of the zygotic seedlings were found towards the end of germination sequence except for seed number 15 and the rest were considered as nucellar seedlings. Based on the fitted logistic regression, the predicted sequence to obtain 90% nucellar seedlings is 5.47. This means that, the germination sequence of less than 6 has 90% chance of getting nucellar seedlings compared to zygotic seedlings. Morphological characters such as number of leaves, stem diameter and leaf area could also be used as references with germination sequence. The results showed that there were significant (p<0.01) relationships between germination sequence and all the growth variables. All growth variables were negatively correlated with germination sequence. This suggested that in order to have 90% chances of getting nucellar seedling (germination sequence below 6), the seedling needs to exhibit several morphology characters; big stem girth, tall plant, high leaf number and large leaf area. Therefore, choosing vigour seedling will increase chances of getting nucellar seedlings, which can be used as cutting source for true-to-type planting material or for breeding purposes.

Aims: This experiment aimed to study the effect of girdling, paclobutrazol application, combined methods, and untreated trees on physiological response, vegetative and reproductive growth, and fruiting. Place and Duration of Study: This study was carried out from August 2021 to June 2022 at MARDI, Serdang, Selangor, using five years of open-field Mangifera indica cv. Harumanis trees. Study Design:  The study was arranged in the frame of  randomized complete block design with three replications and three samples per treatment; ANOVA and DMRT at p=0.05 were used for significance and post hoc comparison, respectively. Methodology: Each replication consists of: T1- No induction (Control); T2- girdling at primary branches; T3- soil drenching at 4 ml/l PBZ and T4- girdling at primary branches + soil drenching at 4 ml/l PBZ. The girdling process was performed by removing a 10 mm width ring of bark at all primary branches. Paclobutrazol (25% active ingredient) of the commercial product was used. The treatments were performed concurrently on 1st December 2021 at the same morphological size as the tree subjected to similar light exposure. Results: The combination method of girdling and paclobutrazol application had the most significant adverse effect on internode length. Nevertheless, no significant difference was observed in plant stem diameter, height, number of primary and secondary branches, and number of shoots generated from all treatments. The combined method reflected a significant reduction in stomatal conductance, rate of photosynthesis, and transpiration rate. However, the intercellular CO2 concentration of this combined method and untreated tree is significantly higher. Flowering appears on the leaf buds 90 days after the treatment for paclobutrazol application and the combined method. These methods also resulted in yield per fruit and yield per tree. Conclusion: Based on the results, the combination method of girdling and paclobutrazol application was effective to reduce vegetative growth, suppress physiological capacity, yet the most effective to produce flowering and fruit yield.