1508 AJCS 5(12):1508-1514 (2011) ISSN:1835-2707 Effect of pyroligneous acid on growth, yield and quality improvement of rockmelon in soilless culture B. Zulkarami 1 , M. Ashrafuzzaman 1* , M.O. Husni 1 and Mohd. Razi Ismail 1,2 1 Laboratory of Food Crops and Floriculture, Institute of Tropical Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 2 Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia *Corresponding author: drashraf2007@yahoo.com Abstract Three fertilizer formulations namely; (M), a local formulation commonly used by farmers, the recommended Cooper standard (CS), and Benoit (BEN) suggested for the lower cost of production were evaluated in combination with four levels of pyroligneous acid (0, 10, 20 and 30%) for enhancement of growth, fruit yield and quality of rockmelon in soilless culture. The addition of 30% pyroligneous acid was toxic as most plants died at this concentration. Twenty percent (20%) pyroligneous acid increased the growth and yield of rockmelon plants, but the local formulation in combination with 10% pyroligneous acid gave the best results. This combination significantly improved plant growth, fruit weight, fruit diameter and sweetness of fruits. Hence the local formulation in combination with 10% of pyroligneous acid is recommended for good fruit yields in rockmelons. Keywords: Pyroligneous acid, fertilizer formulations, rockmelon, growth, yield, quality,soilless culture. Abbreviations: DAT-Days after transplanting PPM-parts per million; EC-electrical conductivity. Introduction Melon (Cucumis melo var. Cantalupensis) is an important commercial crop in many countries. It is mostly cultivated in the temperate regions of the world due to its good adaptation to temperate soil and climate. Rockmelon fruits are highly consumed in the summer and are popular because of it’s sweet pulp and the pleasant aroma (Villanueva et al., 2004). In Malaysia, the cantaloupe type, especially the cultivar ‘Glamour’ (known locally as ‘Golden Langkawi’) with the striking golden yellow color is the favourite. Like other species of melons, cantaloupes thrives best in sandy, well- aerated, moistured soil in weed-free conditions (Zulkarami et al., 2010). Pyroligneous acid or wood vinegar is the crude condensate produced from the distillation of volatiles substances generated in the process of making charcoal. This by-product is rarely used and often disposed off as waste. Pyroligneous acid comprises of small amounts of cadmium (Cd), arsenic (AS) and plumbum (Pb). The synonyms for pyroligneous acid include pyrolysis oil, pyrolysis liquid, wood liquid, liquid smoke, liquid wood, bio-oil, bio-crude oil and wood distillate. Chemically, it occurs as a complex mixture of water, guaiacols, catecols, syringols, vanillins, furan carboxaldehydes, isoeugenol, pyrones, acetic acid, formic acid and other carboxylic acids. Major groups of compounds present in Pyroligneous acid includes; hydroxyaldehydes, hydroxyketones, sugars, carboxylic acids, and phenolics (Fengel and Wegener, 1983; Guille’n and Manzanos, 2002). Wood distillate have been used in traditional agriculture to increase seedling vigour and crop stands (Modi, 2002). In the past decade aqueous pyroligneous acid extracts have been used extensively as germination stimulants in a wide range of plants (Brown and Van Staden, 1997; Van Staden et al., 2000; Brown et al., 2003; Light and Van Staden, 2004). The use of aqueous smoke extracts have not been limited to seed germination. Promontory effects on flowering (Keeley, 1993), Roots (Taylor and Van Staden, 1996) and somatic embryogenesis (Senaratna, 1999) have also been reported. Pyroligneous acid have also been shown to induce new branches, elongate roots, and increase plant height and grain yield (Tsuzuki et al., 1989). Thus, wood distillates (pyroligneous acid) have great potential for utilization in horticulture, agriculture, weed management, habitat restoration and conservation practices (Roche et al., 1997; Boucher and Meets, 2004; Light and Van Staden, 2004). The aim of this study was to compare the effects of three fertilizer formulations (M, CS and BEN) in combinations with different concentrations of pyroligneous acid on plant growth, fruit yield and quality of rockmelon (Cucumis melo L. cv. ‘Golden Langkawi’). Results and discussion Plant height At 17 Days after transplanting (DAT), the tallest plants were recorded in treatments with formulation M (188.83 cm), followed by BEN (177.29 cm), while the shortest plants were observed with the CS formulation (175.23 cm). The taller plants at 10 DAT were recorded with the 0, 10 and 20% concentration of pyroligneous acid (86.78, 95.90 and 86.06 cm, respectively). However, there were no significant