Possibilities of Improving Performance of Direct Seeded Rice Using Plant Growth Regulators: A Review

Abstract

Establishment of adequate rice-stand depends upon seeding density and tillering ability which is critical to harness high grain yield in direct seeded rice (DSR). Maintenance of uniform seedling emergence and establishment is often difficult in DSR. Early growth encompasses an advantage over weed-competition. Vigorous root and shoot growth provide better drought tolerance during vegetative growth. Seedling vigour is also critical when competition for light, nutrients, air and water becomes strongly acute. In order to overcome such production constrains, certain plant growth regulators (PGRs) can prove as effective measure to ensure enhanced germination, better early seedling growth, improved root length and higher yield in DSR. Increased root length by gibberellic acid (GA3) application indicates that GA3 leads to stimulated hydrolytic enzymes. Rice seed treated with triacontanol at 10 ppm increase the germination and vigour index, whereas, GA3 at 100 ppm and kinetin at 10 ppm effectively improve the seed emergence. Seedlings treated with abscisic acid have longer mesocotyls with enhanced elongation periods in rice. Kinetin applied to source organ (flag leaf) of rice decrease the foliar senescence and thus increase crop yield owing to enhanced photosynthetic efficiency. PGRs like GA3, triacontanol, kinetin, abscisic acid, cycocel, NAA, and cytokinin, etc. may enhance the capabilities of DSR against many biotic and abiotic stresses. In this review paper, the authors want to highlight that there are many potential production constraints in DSR which need to be rectified with possible agronomic and agro-chemical interventions like use of PGRs so as to substitute transplanted rice-culture with DSR specifically in those areas where transplanted rice is threatened by certain production vulnerabilities. Nonetheless, Indian farmers are inclining to adopt DSR with higher adoption rates being more productive and profitable to compensate the production cost. Thus, there are ample possibilities to scale-up and sustain the performance of DSR through PGRs besides enhancing environmental quality and food security in rice producing nations.