Disease management for dry direct seeded rice (DDSR) under precision farming system

Abstract

Conventional rice cultivation by transplanting in puddled field requires large amount of water and labour. Water for rice cultivation is becoming scarce due to lowering of groundwater levels and also due to climate change. In Asia, rapid economic development and industrialisation have led to shortage of labour in agriculture. Dry direct seeded rice (DDSR) is a promising resource-saving alternative to transplanting in puddled field and is gaining importance worldwide. The yield in general is 15 per cent less in DDSR than in transplanting. By adopting appropriate crop management such as precision farming integrated with modified planting geometry and suitable crop protection strategies, yield maximisation is possible in DDSR. In this background, a study was conducted to evaluate different disease management strategies for DDSR under precision farming. Field experiments were conducted at the Regional Agricultural Research Station, Pattambi, during late rabi and summer seasons of the year 2025. The experiments were laid out in Randomised Block Design with three replications using rice variety Harsha. Dry direct sowing by dibbling at a spacing of 35-15 cm × 10 cm in paired row planting geometry was followed. The treatments included various combinations of biocontrol agents viz., Arbuscular Mycorrhizal Fungi (AMF), Pseudomonas fluorescens and Trichoderma asperellum. AMF was applied to soil at the time of sowing, Pseudomonas fluorescens and Trichoderma asperellum were applied as seed treatment and through drip. These were compared with normal recommendation of P. fluorescens and T. asperellum as seed treatment, soil application and foliar spray along with a fungicide/antibiotic check and an untreated control. Diseases observed during both late rabi and summer season experiments were sheath blight, bacterial blight and brown spot. Disease incidence and severity were recorded at weekly intervals. The results revealed that the treatment T6 - soil application of AMF (2.5 kg/ha) + P. fluorescens - seed treatment (10 g/kg seed) and two applications of through drip (2.5 kg/ha) + foliar spray of cowdung slurry (20 g/l) was effective for the management of sheath blight, brown spot and bacterial blight. T5 - soil application of AMF (2.5 kg/ha) + T. asperellum - seed treatment (10 g/kg seed) and two applications through drip (2.5 kg/ha) was also equally effective as T6 for the management of sheath blight and brown spot. The total rhizospheric population of fungi and bacteria were higher in treatments where the biocontrol agents were applied. The populations of P. fluorescens and T. asperellum were also higher in treatments in which the respective biocontrol agents were applied. The root colonisation of AMF was higher in AMF applied treatments. The biometric parameters viz., total number of tillers and number of leaves were highest in T6 which were statistically on par with T5. The yield attributes viz., number of productive tillers, number of grains per panicle and 1000 grain weight were significantly high in T6 and were statistically on par with T5. The grain yield recorded was also highest in T6 (7343 kg/ha) which was statistically on par with T5 (7211 kg/ha). The overall results show that soil application of AMF (2.5 kg/ha) + Pseudomonas fluorescens - seed treatment (10 g/kg seed) and two applications through drip (2.5 kg/ha) at tillering and panicle initiation stages + foliar spray of cowdung slurry (20 g/l) at the time of booting is effective for the management of bacterial blight, sheath blight and brown spot of rice in DDSR under precision farming with drip irrigation and fertigation. This study implies that alterations in planting geometry along with integration of biological control agents in DDSR under precision farming can have a significant influence not only in disease management but also in yield enhancement.