Growth and yield responses under different grove floor management strategies for water conservation in young grapefruit trees

Improving sustainable citrus production through soil and water conservation strategies such as plastic mesh groundcovers and raised planting beds has not been thoroughly evaluated. To determine the impacts of these practices on tree growth parameters, fruit yield, and soil environmental conditions we monitored a grapefruit grove (Citrus paradisi Macf. cv.‘Rio Red’) for five years after planting. Trees were planted under four grove floor management strategies that included flat beds with no plastic mesh groundcover (traditional practice), flat beds with groundcover, raised beds with no groundcover, and raised beds with groundcover. The use of ground cover increased soil temperature and moisture content and led to higher tree growth rates and yields relative to uncovered grove floors. Raising the planting bed to approximately 45 cm higher than the surrounding field reduced soil deposition from irrigation and improved soil properties, but caused fluctuations in soil moisture due to improved water infiltration of heavy clay soils compared to the flat beds. Despite the positive effects of the use of ground cover on yields, there was a trend of alternate bearing, smaller and sweeter fruit sizes for trees under this planting design. The traditional method of planting (flat bed with no groundcover) resulted in smaller trees as measured by tree height, canopy circumference, and trunk diameter. While yields were moderate, they were fairly consistent across years and increased slightly each year of the study. These results show that adoption of plastic mesh groundcovers in citrus or other tree fruit production could potentially improve water conservation while increasing production.