The effect of microclimate inside low tunnels on off-season production of strawberry (Fragaria × ananassa Duch.)

Abstract

A field trial was conducted at Horticultural Research Farm, ICAR Research complex for North Eastern Hill Region Umiam, Meghalaya, India to assess the influence of microclimate changes caused by low tunnels and effect of planting time on early production and extension of cropping season of strawberry. The plantings were done at day 10 in July, August, September, October, and November under low tunnels skinned with 75% and 50% shade net, UVS polythene (200μm) and in open field. Irrespective of growing period, the rhizosphere temperature at 20cm depth in polytunnel was higher by 2.64°C, 2.23°C and 1.82°C compared to 75% shade, 50% shade and open field, respectively. During December–January when temperature fell to around 7.0±2.0°C, low tunnel of UVS polythene maintained a temperature range close to 15.0±2.0°C. Similarly during summer months, air temperature was 3.44–5.21°C and 3.6–6.2°C lower, respectively in low tunnels of 75% and 50% shade than in the open field. Whereas, on an average 2–6% higher relative humidity was observed during the whole growing period inside different low tunnel structures compared to the open field. Strawberry was produced 30–35 days earlier than normal in low tunnels of 50% shade planted in July or August. The period of fruit availability was extended to 47 days from normal period under UVS polythene cover when planted in November. Highest yield with firm fruits, higher ascorbic acid, anthocyanin and (-carotene were obtained from the plants planted in November under UVS polythene which was on a par with the plants planted in July and August under 50% shade.