Background: Sowing density optimal is rated a less expensive solution for enhancing the output of tomato yield in the background of extending food requirements worldwide. Methods: The main objective of this study is to investigate the sowing density effect on the growth and tomato yield planted in Don Duong district of Lam Dong province, Vietnam. The study was conducted during the spring tomato crop (January to June 2020) with five different sowing densities varying from 33000 to 50000 plants/ha based on drip irrigation system supply approximately 100% of actual evapotranspiration. Result: Results pointed out that among investigated sowing densities, sowing density 45830 plants/ha obtained the optimal fruit yield (OFY) up to 87.8 tons/ha compared with different sowing densities while other observed variations as the number of bunches, fruit weight per plant and diameter were no significant difference. Based on the findings, tomato growers can sow with a density 45830 plants/ha to obtain the OFY thereby contributing to increase profits.

Background: Globally, irrigation water deficit (IWD) due to saline intrusion and decreased rainfed continues to affect coastal cultivation regions (CCRs). Coastal lowland regions have increasingly frequent saline intrusion, resulting in the IWD as a part of climate variability. Cu Lao Dung Isle, a terrain-low coastal plain in Vietanm is facing revenue loss due to adverse cultivation conditions in recent years. Methods: The objective of this study was, therefore, to assess the effectiveness of the mixture of brackish and freshwater (MBF) for irrigating the spring crop sugarcane in the 2019/20 season grown in a household farming in Cu Lao Dung Isle. An experiment was exploded with the MBF varying from 1.5 to 5.0 dS m-1 corresponding to 100 and 120% of the crop evapotranspiration (ETc). Determination of daily ETc was conducted simulating the FAO-Penman Monteith model based on the weather data obtained using an automatic weather station, locating in the study area. Result: Based on the findings, the MBF at 3.0 dS m-1 levels corresponding to 120% of ETc was stated to be suitable for normal growth of sugarcane Khonkaen III variety. The results showed that the MBF of increasing levels varying from 3.5 to 5.0 dS m-1 significant influenced the growth process and yield of sugarcane. In general, the utilization of brackish water for irrigating in the CCRs is a suitable solution for economic efficiency.