Brought by Eli Vered, R&D Field Crops Manager at Netafim
Ms. K. Vanitha, an M.Sc. student in Crop Physiology at Tamil Nadu Agricultural University in India, submitted an abstract towards her doctoral thesis in Philosophy, on the physiological comparison of surface and subsurface drip systems in irrigating aerobic rice (Oryza sativa L.).
Investigations were carried out during the Dry Season (DS) of 2009, summer of 2010, and DS of 2011, in the Department of Crop Physiology in the Agricultural College and Research Institute in Tamil Nadu Agricultural University in Coimbatore to compare the results of using surface and subsurface drip irrigation for growing aerobic rice, as well as to assess the impact of biogation.
Study Finds Many Advantages of Subsurface Irrigation
Subsurface drip irrigation proved to be better than conventional surface irrigation, for the following:
- The use of subsurface drip irrigation increased the grain yield of aerobic rice, and when used together with biogation, yielded additional advantage. This is due to its favorable root characters, source capacity, and translocation efficiency.
- Subsurface drip irrigation together with biogation favorably influenced the morphological parameters, such as tiller production, root volume, oxidizing power of roots, Root Mass Density, LAI, LAD, and CGR.
- Subsurface drip irrigation improved the biochemical aspects: it promoted increased rate of proline accumulation, enhanced content of endogenous Plant Growth Regulators, negated activities of NRase, ATPase, acid phosphatase, SOD, and increased activities of APX even under the limited water supplying environment.
- Subsurface drip irrigation could comparatively alleviate the water deficit situations for the parameters of plant-water relations in terms of RWC, MSI, and transpiration rate.
- Subsurface drip system improved the uptake of essential nutrients, with or without biogation.
- Yield attributes, which were affected due to the water deficit situation, could be substantially improved with the biogation practice, especially when used with the subsurface drip system thus ultimately resulting in significant improvement in grain yield. These attributes include the number of panicles, number of grains, filled grain percentage, Grain Filling Rate, Harvest Index and TDMA.
- The subsurface drip irrigation treatments indicated its drought tolerance behavior in molecular studies that revealed the expression of putative proteins for the leaf protein profile as observed with low and moderated water levels.
- The subsurface drip irrigation system showed significant improvement of water productivity values, especially with the seaweed extract biogation practice in the chosen aerobic environment.
Study Concludes that Subsurface Drip Irrigation with Biofertigation and Biogation Increases Grain Yield by 17.1 Percent
The investigation proved that the use of subsurface drip irrigation improved the mean grain yield reduction of rice from 24.2 percent as observed with surface irrigation using a limited water supply, to +12.4 percent with the subsurface drip system. The use of seaweed extract for the biogation practice further increased the effectiveness of the subsurface drip irrigation, registering higher benefit: cost ratio of 3.11 in the aerobic ecosystem.
To conclude, scheduling subsurface drip irrigation at 125% PE + 100% RDF together with the use of Biofertigation (Azophosmet) and biogation with seaweed extract performed better than conventional irrigation, with a mean increased grain yield of 17.1 percent.