Morphological Characteristics and Growth Behavior of Ridge Gourd [Luffa acutangula (L.) Roxb.] in Tropical Urban Ecosystem

Ridge gourd (Luffa acutangula) is a climbing vegetable that produces edible fruits. Young fruits are harvested at a time when the seed coats have been established, but cotyledons have not yet formed. This study covered morphological characteristics, growth behavior, and cultivation practices suitable for increasing the production of the ridge gourd in urban ecosystems. Results of observation revealed the heart-shaped leaf of the ridge gourd was very uniform, and the leaf surface was flat so that their leaf area could be accurately estimated using leaf length and/or width (R2 > 0.97). Yet, leaf thickness was not a reliable predictor for the leaf area (R2 < 0.34). The length of petioles was not correlated with the leaf blade area. All single leaves, multiple tendrils, an inflorescence of male flowers and/or a single female flower, and a branch could be formed at each stem node. Water content in the leaf blade was lower than in the petiole. This phenomenon is related to water favor loss due to transpiration activity. Nevertheless, the total conserved water within the leaf blade was 6.26 times more than those within the petiole. The process of fruit enlargement followed the Sigmoid curve. The upper end of the curve started to flatten 10 days after the female flower bloomed. Moreover, at the age of 10 days, cotyledon has not yet formed, so it can be used as a guide to determine the harvest time of the gourd ridge fruit. Based on the leaf SPAD value, by the time the fruit began to enlarge, 4-5 leaves at the stem base were instigated to show symptoms of senescence. Ridge gourd fruit fresh weight can be best estimated using the length × diameter of the plants as a predictor. Keywords: Climbing vegetable, Fruit age, Leaf shape, Sigmoid curve, Urban olericulture