LAUSR

Abstract High density planting system is exploited to increase yield and thereby net return by accommodating higher number of plants in a given area. It is beneficial especially in fruit crops like acid lime where the plant canopy gradually increases over the years and until then land remains unutilized due to conventional wide spacing plantation. In the present study the seedlings of acid lime cv. Pramalini plantation was evaluated under ultra-high density planting (UHD - 1600 trees ha−1 at 2.5 × 2.5 m) and high density planting (HDP - 800 trees ha−1 at 5 × 2.5 m) systems over conventional or control (CON - 400 trees ha−1 at 5 × 5 m) planting spacing. The climate of the study area was tropical, dry, sub-humid having yearly average maximum and minimum temperature 34.2 °C to 20.5 and precipitation of 1128 mm. Field soil having montmorillonitic mineralogy was 40 cm deep. Data on plant growth, soil properties, insect pest (leaf miner), disease (bacterial canker), physico-chemical parameters of fruits and fruit yield were recorded three years after planting of seedlings in the experimental field. It was found that under both UHD and HDP, EC gradually decreased over the period of five years. The highest organic carbon (1.13–1.42 %) and major nutrients were observed under UHD and leaf N and K contents in HDP. Dense and vigorous plant canopy with maximum (1.49) leaf area index was found in HDP and lowest was under UHD (1.18). Although insect – pest and disease incidence was higher in close spacing plantation than CON, physico-chemical fruit parameters were not affected by spacing. The fruit yield on per plant basis was always significantly lowest under UHD. However, on area basis, under UHD plantation fruit yield (8.24–35.36 t ha−1) was more than two folds as compared to control (3.08–11.64 t ha−1) for different years. Although during last year of experiment the yield under ultra-high density planting (35.36 t ha−1) was significantly higher than high density planting (25.09 t ha−1), the B:C ratio was nearly similar in both the cases. Therefore, it may concluded that the high density planting system may be preferred during early years of production.