YIELD AND AGRONOMIC VARIABLES OF RICE PSB Rc52 (GANDARA) AS AFFECTED BY CROP ESTABLISHMENT, FERTILIZER SOURCES AND RATES OF APPLICATION

Abstract

Yield response and agronomic traits of directly seeded and transplanted lowland rice applied with inorganic, organic and foliar fertilizer using different rates were evaluated using a randomized complete block design in a split-split plot arrangement.

Results showed that directly seeded rice during the February to June cropping (Table 1.) were significantly taller at 35 DAS (38.04 cm), matured earlier (117.85 days), produced more number of productive tillers (21.17) and more number of spikelets per panicle (116.97). Transplanted rice were significantly shorter with 27.95 cm height at 35 DAS, had delayed maturity (123.33 days) and significantly developed less number of spikelets (107.77) per panicle. Application of inorganic fertilizer during this season significantly induced the production of more tillers (21.56/hill) and number of spikelets/panicle (116.48). However, this treatment also had the highest blight infection (85.42%) compared to those fertilized with organic and foliar fertilizer which had statistically comparable results. A similar trend of response was observed among plants applied with various sources of fertilizers. Inorganic fertilizer on rice significantly induced early flowering (87.11 days).

Grain yield was significantly higher in direct seeded (3288.81 kg/ha) compared to transplanted (2135.84 kg/ha) crops during the February to June cropping because the percent tungro infection of direct seeded was lower (46.65%) compared to transplanted which was higher (48.38%). The tungro infection was first spotted and recorded when the plants were 21 days old or 1 week after the transplanted crops were established in the field. Newly established crops were weak because they were still recuperating from stress in transplanting shock, thus vulnerable to infection. Tungro was prevalent in the experimental area due to asynchronous rice planting and the use of cultivars, which were homogenous genetically and high yielding variety (Sebastian, 1995).

During the July to November cropping, the directly seeded rice exhibited early flowering (86.7 days) and mature (107.3 days) with taller plants at 35 DAS (30.30 cm) compared to transplanted whose flowering and maturity were delayed at 91.55 and 113.89 days, respectively. The methods of crop establishment did not significantly affect other agronomic traits, such as yield and yield components of rice. However, the percentage blight severity significantly increased with direct seeding, 67.31% compared to transplanting 52.04%. The rate of fertilizer application affected only the plants height at maturity and the number of productive tillers during the wet season. Application of the recommended rate (90-45-45 kg NPK/ha) + h RR (135-67.567.5 kg NPK/ha) developed the tallest plants (73.37 cm) and the most

number of productive tillers (21.53) per hill. The grain yield was statistically comparable although the transplanted yielded relatively highly (3636.84 kg/ha) as compared to direct seeded (3245.67 kg/ha). This was a contradiction of the previous planting because of its significantly low percent sheath blight infection (52.04%) and low tungro infection (43.76%) compared to those from the direct seeded which was 67.31% and 46.87%, respectively. The high gross income for direct seeded rice (Table l) was applied with inorganic fertilizer h above RR (135-67.5-67.5) with a grain yield of 4509.44 kg/ha, which also gave the highest net income of P30391.06, but for the highest ROI were the plants applied with RR (90-45-45) with 190.76%. For transplanted rice, the highest gross income (P45190.38) was applied with foliar h below RR (9.99 li GB + 13.33 li YB/ha) with also the highest net income of P31242.08, and the highest ROI of (224.92%) was the one applied with inorganic fertilizer h below RR (45-22.5-22.5 kg NPK/ha). This treatment got the lowest incidence of tungro infection compared to the rest of the treatments.