Response of lowland rice (Oryza sativa Linn.) var. NSIC Rc216 to the application of paclobutrazol grown in acidic and alkaline soils

Abstract

This study sought to assess the effect of paclobutrazol on the performance of lowland rice when grown in acidic and alkaline soils. Determine the soil type that can produce maximum productivity, and evaluate the profitability of growing lowland rice to the paclobutrazol application under acidic and alkaline soils. The experiment was set out in a split plot organized in RCBD with soil types (ideal, acidic, and alkaline) as the main plot while the time of paclobutrazol is the subplot. The time of paclobutrazol application is indicated as follows: S1control, S2at the vegetative stage, S3at the heading stage, and S4in both vegetative at heading stages. Statistical analysis revealed that regardless of the time of paclobutrazol application in lowland rice ideal soil showed a significant influence in most agronomic and yield and yield component parameters, and achieve the highest gross income (PHP 143,820.00) and gross margin of PHP 100,368.72. The application of paclobutrazol at heading (S3) shows a significant outcome on the number of nodal roots plant -1 (411.11) and obtained the highest gross income comparing other subplot treatments. A remarkable effect on leaf area index (2.27), fresh straw yield (8.37 t ha -1 ), and root length (41.53 cm) were obtained in S3 plants and had a higher grain yield of 3.77 t ha -1 . Paclobutrazol is advisable in lowland rice regardless of the time of application under ideal soil to effect higher productivity. This can promote the development of panicles when applied under acidic soil.

Response of second ratoon lowland rice (Oryza sativa L.) var. NSIC RC222 to paclobutrazol at different levels of application

“…The result of the study might be due to the response of second ratoon lowland rice to the application of paclobutrazol at a lower level (50ppm) and at higher levels (400ppm until 600ppm) that reduced the number of nonfunctional NRs per plant (Table 5). The result of this study was similar to the findings of Balano (2021) that lowland rice applied with paclobutrazol at the rate of 500ppm during both vegetative and heading stages remarkably achieved the shortest root length (35.79 cm) when compared to non-applied control plants which emanated significantly the longest root length of 45.60 cm.…”

“…The solution was diluted in one liter of water and sprayed in each treatment. To produce 1,000 ml paclobutrazol solution this formula was used (Balano, 2021):…”

“…As observed that ratooned plants having longer panicle length (31.56cm) also produced a greater number of 194.90 spikelets panicle -1 when compared to non-applied control plants with a fewer number of spikelets panicle -1 of 94.20 spikelets. Balano (2021) stated that the application of paclobutrazol at the heading stage remarkably produced longer panicle lengths comparable to non-applied control plants. The result agrees with the finding of Plaza-Wuthrich et al (2016) that paclobutrazol application enhanced the number of panicles of tillering crops under stressed conditions but not when exposed under normal conditions.…”

“…Sometimes application of this growth retardant caused positive effects such that paclobutrazol is used in ornamental plants to limit height to improve aesthetic value (Duck et al, 2004). Balano (2021) reported that lowland rice applied with paclobutrazol at the rate of 500ppm in both vegetative and heading stages has the shortest plant height (51.94 cm) when compared to rice plants not applied with paclobutrazol that producing substantially a taller plant height of 85.97 cm. In the study of Mactal and Canare (2015), the application of 500ppm paclobutrazol has no significant reduction in plant height.…”

“…Other paclobutrazol applied plants produced comparative LAI ranges from 4.97 to 6.39 when compared to T4 plants. Balano (2021) mentioned that the application of paclobutrazol at 500ppm during the vegetative stage gave a tremendous reduction in LAI (1.79) than those rice plants applied at heading (2.27) and also in non-applied control plants with an LAI value of 2.72. Since the leaves are responsible for the absorption and interception of solar radiation for plant growth and development, this directly means broader leaf area and greater leaf area index can contribute to higher productivity.…”