Question: query regarding how to increase the production of bottle gourd. 
Answer: if you apply the recommended doses of fertilizer in your field then now you can spray one vitamin like plenofix 1ml/4 liter of water or mohaphol 2ml/liter of water or sagorika 2ml/liter of water once at flowering stage and once at fruit initiation stage in the evening time in the absence of rain. also apply 25 gram borax per plant in ring method 30 cm away from the plant or you can spray 3 times once in a week in the evening time in the absence of rain.