Morphological Growth and Biomass Allocation Responses of Acacia auriculiformis Seedlings to Varying Watering Intervals

Abstract

Water availability strongly influences early seedling establishment and nursery performance. This study examines how varying watering intervals affect the morphological growth and biomass allocation of Acacia auriculiformis seedlings under controlled nursery conditions. Over 13 weeks, seedlings were watered at five different frequencies: daily and every 4, 8, 12, and 16 days. The research focused strictly on physical growth patterns rather than physiological responses to drought intensity. Results showed that extended watering intervals consistently stunted above-ground development; average shoot length dropped from 60.25 cm in the daily control group to just 18.69 cm under the 16-day interval. However, a four-day watering interval stimulated below-ground growth. These seedlings achieved a maximum root length of 29.43 cm and a total plant biomass of 9.42 gm, outperforming the daily-watered control. This adaptive growth strategy was further supported by a significantly lower shoot-to-root ratio during the 4-day and 8-day intervals. The data indicated that the seedlings actively redirected biomass to their root systems to cope with moderate water stress before the severe growth declines observed at the 12-day and 16-day intervals.