Response of modified microclimates on growth, yield, and incidence of rhizome rot disease of ginger in Assam, India.

Abstract

Field experiments were conducted at Biswanath, Assam, India (26° 42' N and 93° 15' E), during 2016, 2017, and 2018, to evaluate the effect of microclimates on growth, yield, and disease incidence in the ginger crop. The ginger variety Nadia was grown under six microclimates, viz., under shade net for the entire crop season (T1), under shade net from planting to mid-October (T2), with pigeon pea (T3), with maize (T4), with okra (T5), and as a sole crop (T6) in three replicated RBD. Photosynthetically active radiation (PAR), net radiation (Rn), temperature above the ginger canopy, soil temperature, and soil moisture were measured during the critical crop growth period under different microclimates. Recording of rhizome rot disease incidence was done periodically and genomic analysis of pathogen was carried out. PAR recorded above the ginger canopy under T6 was 1688.1 μ mol s-1m-2, which was attenuated up to 80.1% in other microclimates. The Rn load of the ginger canopy was maximum (446.4Wm-2) under T6, which reduced to below 50Wm-2 under both T3 and T4. Both air temperatures above the ginger canopy and soil temperatures under T3 and T4 were reduced by 3.3°C and 4.6°C, respectively, as compared to T6. The pathogen causing the disease in the experimental site was identified as Fusarium oxysporum. Considerable increase in soil and air temperature and soil moisture favored disease incidence (90.3%) under shade net (T1 and T2) treatments, while opposite reason causing significant reduction in disease incidence (16.1%) was observed under T3 and T4. More yield of ginger recorded in treatments T3 (6.21 t ha-1) or T4 (6.48 t ha-1) was attributed to better crop growth and diminutive disease incidence, while the crop was almost damaged due to severe disease incidence under shade net (T1 and T2) treatments.