Effect of land configuration, drip lateral placement and scheduling of irrigation on growth and yield of Rabi Garlic (Allium sativum L.)

Introduction

Garlic (Allium sativum L.) belongs to the family Alliaceae and is the second most consumed bulb crop after onion. It has a strong sulfurous smell and flavour due to the presence of allicin, an antibacterial oil. Garlic has numerous medicinal properties, primarily attributed to its active compound allicin, which has antibacterial and antifungal effects. As a shallow rooted crop, garlic is particularly vulnerable to moisture stress, especially during the bulb development stage, which requires effective irrigation scheduling to enhance yield, bulb quality and water use efficiency. Drip irrigation plays an alternative to traditional flood irrigation by delivering water directly to the root zone. This method minimizes water loss and improves nutrient availability and crop productivity. However, the primary expense associated with drip irrigation arises from the cost of drip laterals. In heavy black soils, increased lateral water movement may allow for wider spacing of drip laterals through appropriate plant geometry, which reduce the system costs. Additionally, planting techniques affect soil aeration, drainage, root development and bulb growth, with raised beds typically offering superior conditions compared to flatbed planting. The limited information on the combined impact of planting methods, drip lateral spacing and scheduling of irrigation for garlic in South Gujarat, this study was initiated to assess their effects on growth and yield of garlic cultivation.

Materials and Methods

A field experiment was conducted during the rabi season of 2024-25 at soil and water management research farm, Navsari Agricultural University, Navsari. The soil used in the experiment was clay, exhibiting a pH of 7.49, an electrical conductivity (EC) of 0.29 dS m -1 and an organic carbon content of 0.84%. The soil was characterized by low levels of available nitrogen (206.72 kg ha -1 ), medium levels of available phosphorus (29.22 kg ha -1 ) and high levels of available potassium (488.01 kg ha -1 ). The experiment included twelve treatment combinations, which consisted of two land configurations (L 1: Flatbed and L 2: Raised bed), two placements of drip laterals (S 1: One lateral per 8 rows and S 2: Two laterals per 8 rows) and three levels of irrigation scheduling (I 1: 0.6 PEF, I 2: 0.8 PEF and I 3: 1.0 PEF). This was organized in a Factorial Randomized Block Design with four replications. Raised beds were prepared by top width of 80 cm, furrow width of 40 cm and depth was 30 cm. The recommended fertilizer dose for the crop was 100:50:50 kg ha -1 of NPK. Out of the total nitrogen (N) and potassium (K 2 O), 10% each was applied as a basal dose at the time of sowing, along with 100% of the recommended phosphorus (P 2 O 5 ). The remaining 90% of nitrogen and potassium was applied in ten equal splits at intervals of 10-12 days, commencing from 15 days after planting. The mean maximum temperature fluctuated between 29.6°C to 37.3°C, whereas the minimum temperature varied from 12.9°C to 20.6°C throughout the experimental period. The maximum and minimum relative humidity levels were recorded between 63% to 92% and 17% to 49% at morning and evening respectively. One common surface irrigation of 60 mm depth was given at the time of sowing for proper planting and establishment of crop, then the system was operated as per treatment on an alternate day basis. Irrigation was ceased two weeks prior to the crop harvest. Five plants were randomly selected from the net plot area for recording growth observations. Bulb yield was recorded from net plot area. The data obtained were subjected to statistical analysis as suggested by Panse and Sukhatme (1985) [7] .

Results and Discussion

Effect of land configuration

Raised bed planting (L 2 ) achieved significantly superior growth parameters, including plant height, number of leaves, neck thickness, dry weight of leaves, dry bulb weight and total dry plant weight, as compared to those from flatbed planting (Table 1). Treatment L 2 also showed significantly greater bulb width, bulb diameter, bulb weight and bulb yield (Table 2). The superior yield observed in raised bed planting can be attributed to enhanced soil aeration, effective drainage, improved root development, moisture and nutrient availability in the root zone. Furthermore, raised beds assist in reducing temporary water stagnation and establishing favourable soil physical conditions for bulb development. As garlic is a shallow-rooted crop, it responds favourably to well-aerated soil conditions, resulting in enhanced vegetative growth and bulb formation. The results corroborate the earlier findings of Dodake (2005) [2] , Kadari et al. (2019) [3] and Kaur et al. (2022) [4] , who recorded markedly higher yield of garlic when planted on raised bed.

Effect of drip lateral placement

Between the two treatments for drip lateral placement, the installation of two laterals for every 8 rows (S 2 ) demonstrated a significantly higher values of all the growth parameters, yield attributes and yield of garlic as compared to one lateral per 8 rows (S 1 ) (Table 1 and2). The increase in growth and yield associated with double lateral placement is likely due to the uniform distribution of water in the crop root zone and the maintenance of optimal soil moisture levels throughout the growing period. The superior wetting pattern under double lateral placement promotes nutrient uptake, photosynthesis and the movement of assimilates towards bulb development. Similar results were obtained by Patel et al. (2014) [8] and Mehla et al. (2022) [6] .

Effect of irrigation scheduling

The results presented in Table 1 and 2 showed that increasing the drip irrigation schedules from 0.6 PEF to 1.0 PEF caused significant increase in growth and yield attributing characters. However, in most of the cases, including bulb yield treatment 0.8 PEF and 1.0 PEF remained at par with each other. In the present study, the higher growth and yield of garlic recorded under the 1.0 PEF and 0.8 PEF irrigation scheduling were mainly attributed to the favourable maintenance of soil moisture and the uniform application of irrigation water throughout the crop growth period. Another possible reason is that the continuous availability of moisture under this treatment improved nutrient availability and uptake during the entire growing season, which promoted better vegetative growth, enhanced bulb development and ultimately resulted in higher garlic yield. Increased yield with drip irrigation was also reported by Sankar et al. (2008) [10] , Mathukia et al. (2014) [5] , Der et al. (2018) [1] and Sahu et al. (2023) [9] .

Conclusion

Based on the findings of the field experiment conducted during the rabi season of 2024-25, raised bed planting proved superior to flatbed planting for achieving higher bulb yield in garlic cultivation. Further the use of two drip laterals per eight rows improved bulb yield as compared to one lateral per eight rows. Irrigation scheduling at 1.0 PEF and 0.8 PEF recorded higher growth, yield attributes and bulb yield than 0.6 PEF.

References

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