Optimal fertilizer requirement of Gac to enhance growth, yield and carotenoid content

Abstract

Gac is widely recognized and in high demand as a nutritional product due to its rich carotenoid content, particularly lycopene and beta-carotene. However, information regarding the cultivation and optimal fertilizer requirements for Momordica species, including Gac, is limited. This study aims to determine the most effective fertilizer dosages to enhance Gac growth and maximize fruit quality, including carotenoid content. Four different combinations of single-fertilizer rates (Urea, Triple Superphosphate, and Muriate of Potash) were assessed on different growing stages. All Gac plants exhibited increased growth parameters during the growth phase. Treatments 1 and 4 demonstrated notably faster and greater vine growth compared to Treatments 2 and 3. Treatment 2 exhibited delayed growth and produced the lowest branch number, while Treatment 4 recorded the highest leaf count. However, no significant differences were observed in fruit characteristics (average fruit weight, total weight, fruit length, diameter, and aril weight) among the treatments (p > 0.05). At the same time, the number of fruits per plant varied significantly, with Treatment 4 indicating a 38.8% increase over Treatment 2 and results similar to those of Treatments 1 and 3. Lycopene analysis revealed that fruits from Treatment 1 had significantly higher levels (p = 0.0012) than those from all other treatments. Conversely, β-carotene levels in Treatments 1, 2, and 3 were comparable, at 312.88, 286.34, and 258.40 mg/g fresh weight (FW), respectively. In conclusion, Treatment 1 provided the most balanced fertilizer regime, promoting stable vegetative growth, comparable fruit yield, and significantly higher lycopene accumulation, indicating its suitability as the optimal fertilizer strategy for Gac cultivation under the conditions of this study.