Root Restriction for Growth Control and Precocity in Starfruit (A Verrhoa Carambola L.)

Starfruit (Averrhoa carambola) is an important fruit grown commercially in Malaysia. High rainfall and plentiful sunshine of the humid tropic usually promotes abundant shoot growth. Tree height increment is also tremendously fast. These conditions could lead to increase vegetative growth. Innovative technique is therefore needed to control vegetative vigour. Root restriction offers an effective and safe method of reducing tree size and canopy development. The main objective of this research is to study the response of starfruit to root restriction treatments under in the glasshouse and field condition. Root restriction studies have previously been conducted mainly in starfruit, they were preceded by preliminary studies on apple (Malus domestica) and pear (Pyurus communis) in the United Kingdom. Preliminary studies in apple grown in different container shapes and volumes showed that root and shoot growth responded to both container dimensions and their interactions. Large volumes (1 2 litre) with high pot depths enhanced root growth, thereby increasing shoot growth. However, effects of root growth restriction were observed when container shape or volume was reduced resulting in decreased root and shoot growth, and nutrient levels. Root : shoot ratio remained consistent irrespective of changes in container volume or shape. Studies on pear trees (Py rus comm unis) subjected to different shapes and volumes Df porous root restrictive membrane suggested that reduction in soil volume to 9 1 litres resulted in 35 and 38% reduction in girth increment and shoot length, respectively. Fruitset and average weight per fruit were unaffected, but leaf P concentration was reduced during the first year of plailting. Similar treatments tested on starfruit (Av errho a c aram bo la) grown in different container shapes and volumes indicated that gmwth responded mostly to container volumes. Root and shoot growth reduced with decrease in container volume. Detailed root studies using root observation chambers showed that reduction in chamber volume decreased root branching and root elongation but root length density (RLD) increased although coarse root length and root tip density did not change. Root surface area (RSA) was also reduced when root chamber volume decreased. It was concluded that the reduction in shoot growth was the result of reduced root growth and development

Response of starfruit shoot and root to varying rooting volumes

Shoot and root responses of root-pruned starfruit (Averrhoa carambola) seedlings in different rooting volumes, were studied using root observation chamber. Plant height and internode number were linearly correlated with rooting volumes over time, but stomata and epidermal cell number showed no response. Negative linear relationship was shown between the first-order root laterals and distant from root apex but root elongation had positive linear correlation with rooting volumes. Root length density, root surface area and total root length were significantly influenced by rooting volumes. However, there was no significant response on root tip density, coarse root length, percentage of dry matter distribution and root:shoot ratio. Leaf concentrations of N, P and Ca were significantly increased by rooting volumes but K and Mg were unaffected. A positive linear response between root elongation and plant height was observed

Extraction and characterization of pectin from dragon fruit (Hylocereus polyrhizus) using various extraction conditions. (Pengekstrakan dan pencirian pektin daripada buah naga (hylocereus polyrhizus)menggunakan pelbagai keadaan pengekstrakan)

The extraction of pectin from dragon fruit (Hylocereus polyrhizus) peels under three different extraction conditions was identified as an alternative source of commercial pectin. In this work, dried alcohol-insoluble residues (AIR) of dragon fruit peels were treated separately with 0.25% ammonium oxalate/oxalic acid at a pH of 4.6 at 85oC; 0.03 M HCl at a pH of 1.5 at 85oC; and de-ionized water at 75oC. The pectin obtained from these methods was compared in terms of yield, physicochemical properties and chemical structure. Fourier Transform Infrared Spectroscopy (FTIR) was used in the identification of dragon fruit pectins. The results showed that the pectin yield (14.96-20.14% based on dry weight), moisture content (11.13-11.33%), ash content (6.88-11.55%), equivalent weight (475.64-713.99), methoxyl content (2.98-4.34%), anhydrouronic acid (45.25-52.45%) and the degree of esterification (31.05-46.96%) varied significantly (p < 0.05) with the various extraction conditions used. Pectin extracted with ammonium oxalate gave the highest yield of pectin, with high purity and low ash content. Based on the value of methoxyl content and the degree of esterification, dragon fruit pectin can be categorized as low-methoxyl pectin