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

Abstract

Paclobutrazol enhances the productivity of lowland rice when applied during the second ratoon cropping. This study sought to determine the response of second ratoon lowland rice to paclobutrazol at different levels of application. Determine the specific level of paclobutrazol application that can produce maximum productivity, and evaluate the profitability of growing second ratoon lowland rice applied to paclobutrazol at different levels of application. The study was set out in a Randomized Complete Block Design (RCBD) with levels of paclobutrazol application as treatment and replicated three times. The paclobutrazol application treatments were; T 0 – no paclobutrazol application (control), T 1 – paclobutrazol at 50ppm, T 2 – paclobutrazol at 100ppm, T 3 – paclobutrazol at 200ppm, T 4 – paclobutrazol at 300ppm, T 5 – paclobutrazol at 400ppm, T 6 – paclobutrazol at 500ppm, and T 7 – paclobutrazol at 600ppm. Statistical analysis revealed that second ratoon lowland rice applied with 300ppm paclobutrazol (T 4 ) significantly produced a taller plant height, an abundant number of tillers hill -1 , greater LAI, higher percent of tall tillers with elongated panicles, higher fresh straw yield, longer root length, more number of nodal roots plant -1 , longer panicle length, abundant spikelets per panicle, and produced remarkably the highest grain yield when compared to unsprayed control. This treatment achieved the highest gross margin (USD764.11) than those other treatments adopted. This study enlightens the ratoon growers regarding the physiological biochemical responses of ratoon crops to the application of paclobutrazol as a growth regulator in enhancing rice productivity.