RESPONSE OF INBRED AND HYBRID LOWLAND RICE (ORYZA SATIVA L.) VARIETIES TO NAPHTHALENE ACETIC ACID (NAA) AND INORGANIC FERTILIZERS

Abstract

The study was conducted in an irrigated lowland area in Barangay Tagbibi, Hindang, Leyte, Philippines last January to April 2021. This study aimed to determine the effects of NAA and inorganic fertilizer on the agronomic parameters of lowland rice; and evaluate the economic profitability using NAA as plant growth regulators (PGR) combined with inorganic fertilizers. The experimental area was laid out in a split-plot arranged in RCBD with three replications. Lowland rice varieties V1= hybrid rice and V2= inbred rice was designated as the main plot while PGR (T1 = control [no application], T2= 500 ppm NAA + ½ RR, T3 = 1000 ppm NAA + ½ RR, and T4 =120-60-60 kg ha-1 N, P_2 O_5, K_2 O [RR]) as the subplot. Results revealed that application of PGR, significantly affected the agronomic characteristics of hybrid and inbred lowland rice varieties. Rice plants applied with NAA regardless of the levels (500 ppm & 1000 ppm-T2-T3), comparable to unfertilized plants headed and matured earlier than the plants applied with full RR 120-60-60 kg ha-1 N, P_2 O_5, K_2 O. Application of 1000 ppm NAA+ ½ RR produced more numbers of productive tillers hill-1 and a higher percentage of filled spikelets. Plants that received NAA regardless of the concentration (T2-T3) significantly obtained heavier panicle weight (g) and consequently grain yield (tha-1). Hybrid and inbred lowland rice varieties obtained the same net income of PhP50,066.05 and PhP51,876.76, respectively. However, highest net income of PhP61,605.67 was obtained by inbred rice applied with 500ppm NAA + ½ RR followed by hybrid rice applied with 1,000 ppm NAA + ½ RR with a net income of PhP 58,215.17.