No abstract

This laboratory experiment was carried out at the Department of Agricultural Technology, Mahasarakham University, Northeast Thailand during July and August 2008. The experiment aimed to determine an effective natural organic acid that would delay the unattractive skin browning of santol fruit, while at the same time not damaging the quality of the fruit. The experiment included a study of the fruit's polyphenol oxidase (PPO) activity, phenolic content and quinone content, as they relate to colour and a study of total soluble solid content, pH, titratable acidity and vitamin C content as they relate to fruit quality. A Completely Randomized Design (CRD) with four replications was used. Each replication consisted of 10 fruits. Santol fruit was harvested at 145 days after full bloom and dipped for 30 min in aqueous solutions of two organic acids that were used as treatments, i.e., 0% for T1 (control), 5% citric acid for T2, 5% ascorbic acid for T3, 10% citric acid for T4 and 10% ascorbic acid for T5 and stored at room temperature (28 degrees C, 90% R.H.) to investigate the effect of the acid on fruit weight, skin colour, PPO activity and other internal parameters. The results showed that the most appropriate anti-browning agent for santol fruit was found with T2. It gave the highest mean values, 57.37 and 55.95, of brightness (L*) at 4 and 10 Days After Storage (DAS), respectively. In addition, PPO activity of flesh tissue was lowest for T2 with mean values of 0.0078 to 0.0092 by 0 and 300 S, respectively. The phenolic content in the flesh tissue significantly increased with an increase in numbers ofDAS, whereas the reverse was found with the pH level in the fruits. They were lowest for T2, with mean values of 6.00, by 10 DAS. There were no significant differences among the treatments in any of the measured Total Soluble Solids (TSS), Titratable Acidity (TA) and vitamin C content.

This green manure experiment with the use of okra crop as indicator plant was carried out at Mahasarakham University Experimental Farm, Mahasarakham province, Northeast Thailand during May to September 2005 to investigate four types of green manure legume crops on growth, yield and quality of edible fresh pods of okra crop when grown on Roi-Et soil series (Oxic Paleustults). The four types of green manure plants include Jack bean, Cowpea, Green gram, and Giant sensitive plant. The experiment consisted of five treatments, i.e., T1 (Control), T2 (Jack bean), T3 (Cowpea), T4 (Green gram) and T5 (Giant sensitive plant). The experiment was laid in a Completely Randomized Design (CRD) with four replications. The results showed that Roi-Et soil series (Oxic Paleustults) contained some considerable mean values of organic matter (1.64-1.66%) but soil available phosphorus and exchangeable potassium were relatively low, particularly potassium. Green manures of the four legume plants slightly improved soil property of the Roi-Et soil series (tested at the end of the experimental period). The most effective green manure on stem diameter, bushy diameter, leaf numbers plant(-1) and leaf area of the fifth leaf of the okra plants, in most cases, was found with Jack bean and Cowpea ranked the second. However, in most cases, Cowpea gave a similar effect as that of Green gram and Giant sensitive plant. Pod length and weight pod(-1), pod diameter and edible fresh pod yields (5941.86 kg ha(-1)) were highest with Jack bean green manure treatment (T2), whilst the rest, in most cases, were similar. Green manure treatments gave highly significant effect on total soluble solids of pods over the control treatment, whilst total acidity, fibre and pectin contents were unaffected by green manure treatments. Green manure of Jack bean was the best legume crop for green manure to be used in improving soil fertility, particularly for Roi-Et soil series (Oxic Paleustults).

<p>‘Maha Chanok’<strong> </strong>mango is an economic fruit crop widely cultivated commercially throughout Thailand. By nature, mango fruit has a rather limited storage life after harvest. 1-methylcyclopropene (1-MCP) has been accepted as a commercial substance to improve several fruit qualities. The objective of this research was to study the effects of 1-MCP on the external postharvest qualities and storage life on the ‘Maha Chanok’ mango fruit. The experiment was laid out in a Completely Randomized Design with three replicates, ten fruits per replicate. Mango fruit was fumigated with 1-MCP at three concentrations (1000, 1250, or 1500 nl l^-1) and three fumigation periods (12, 18, or 24 h), compared with the control fruit. After treating, all treatments were stored under ambient temperature (27 °C, 80%R.H.). The following determinations were made every two days for assessment of fruit weight loss, firmness, chlorophyll content, decay incidence, and storage life. The results showed that fruit treated with 1500 nl l^-1<strong> </strong>1-MCP for 24 h had the maximal fruit firmness. For chlorophyll content, the results showed that fruit-treated with 1500 nl l^-1<strong> </strong>1-MCP for 12 h could effectively retain the highest chlorophyll contents. Furthermore, both the lowest fruit decay and the longest storage life of 12 days were achieved from the fruit treated with 1000 nl l^-1<strong> </strong>1-MCP for 12 h.</p>

This laboratory experiment was carried out at the Department of Agricultural Technology, Mahasarakham University, Northeast Thailand during June to October 2007. The experiment aimed to search for the most appropriate harvesting age of fruits of Santol orchard plants with respect to colour, tissue texture, total soluble solid content, titratable acidity and pH of Santol fruits. A Randomised Complete Block Design (RCBD) with four replications was used. Each replication consisted of 10 fruits, thus a total of 160 fruits were used. The Santol fruits were harvested at different ages, i.e., 100, 115, 130 and 145 days after full bloom of flowers and these harvested ages were used as treatments, i.e., 100 for T1 (Control), 115 for T2, 130 for T3 and 145 for T4. The results showed that the most appropriate harvesting date for high quality Santol fruits was found with T4, i.e., 145 days after full bloom of flowers where Santol fruits of T4 gave the highest mean values of fruit length, diameter, fresh weight fruit(-1) of 10.71 cm, 9.31 cm and 399.76 g, respectively. Yellowness of skin colour of fruits was evenly distributed. Total soluble solid content of pericarp, flesh tissue and seeds were highest for T4 with mean values of 13.93, 15.05 and 18.260 brix, respectively. Flesh texture density highly decreased with an increase in numbers of days after full bloom of flowers. Titratable acidity content in fruits was highly decreased with an increase in numbers of days after full bloom of flowers whereas a reverse was found with pH of fruit juices.

Papaya (Carica papaya L.) is an important fruit widely cultivated commercially throughout Thailand. Its all year around fruit bearing capability makes papaya a popular fruit with Thai people. Unfortunately, papaya has a very limited shelf-life, as such; the objective of this research was to delay the external postharvest qualities by using chitosan and calcium chloride on the 'Holland' variety of papaya fruit. The experiment was arranged in a Factorial Completely Randomized Design, composed of two factors: coating with chitosan at four concentrations (1.0, 1.5, 2.0 or 2.5%) or dipping in calcium chloride solution at four levels (1.0, 1.5, 2.0, or 2.5%), compared with control fruits. After treating, all treatments were stored under ambient temperature (27 C, 80% R.H.). The results showed that fruit treated with chitosan, irrespective of any concentrations, had the least similar fruit weight loss after six days of storage; however, fruit-treated with 2.5% chitosan showed the maximum fruit firmness and a delayed red color appearance on the fruit skin. In addition, the best treatment for extending shelf-life proved to be from a treatment of 2.5% chitosan.

A comprehensive study to evaluate calcium, in terms of gypsum (CaSO4.2H2O) by soil dressing application, on enzymatic browning activity of Polyphenol oxidase (PPO) and internal qualities was tested on lettuce var. Grand Rapids under field conditions. A factorial in completely randomized design was arranged with four replications. The results showed that plants-treated with 50 mg kg(-1) gypsum applied at 40 DAP had the maximal fresh weight of 25.83 g plant(-1). The internal qualities of the lettuce at harvest showed that plants treated with 50 mg kg(-1) gypsum had the maximal chlorophyll content (26.80 mg m(-2)), while all gypsum concentrations applied in this study, had less content of ascorbic acid than the control plants. Plants-treated with 100 mg kg(-1) gypsum affected to the lowest level of PPO activity at week 3 after transplanting. Furthermore, gypsum application had no effect to biomass, leaf colour, the contents of phenolic and quinone in lettuce at harvesting stage.

This investigation was carried out at Mahasarakham University Experimental Farm, Mahasarakham University, Northeast Thailand in the late rainy season of the 2003 to 2004 with the use of Roi-Et soil series (Oxic Paleustults). The experiment aims to search for more information on the effect of different rates of chemical Paclobutrazol (PBZ) application on growth, yield and quality of edible okra pods. A Randomised Complete Block Design (RCDB) with four replications was used for the experiment. The experiments consisted of five treatments, i.e., 0 (T1), 4000 (T2), 8000 (T3), 12,000 (T4) and 16,000 ppm ha(-1) (T5) of chemical PBZ. The results showed that an increase in PBZ application rate highly decreased plant height, harvesting age and significantly decreased leaf area of the fifth leaf but highly increased pod length, fresh weight/pod and fresh pod yield ha(-1) of the okra plants. PBZ had no significant effect on stem diameter and diameter of pods of the okra plants. Total soluble solid, fibre content, titratable acid, vitamin C and pectin contents in pods were not affected by chemical PBZ application. Pod yield highly increased with an increase in rate of PBZ application. The highest edible pod yield reached a value of 4501 kg ha(-1) for the highest rate of PBZ application (T5).