XVIII. Elucidation of Growth Promotion Mechanisms of Radiation-Modified Carrageenan and Chitosan on Rice
Study 1. Effect of radiation-modified carrageenan application on the growth, nutrient, and yield of rice
A pot experiment was conducted under greenhouse condition at PhilRice-CES (Central Experiment Station), Maligaya, Science City of Muñoz, Nueva Ecija during the dry season 2014 to determine the influence of radiation- modified carrageenan application on the growth, nutrient uptake, yield and yield components of rice and to establish optimum rate of application of carrageenan and chitosan for increased nutrient uptake.
Twelve (12) treatments were included: two rates of inorganic fertilizer, 90- 40-40kg NPK/ha which is the recommended rate (RR) and half RR (45-20- 20kg NPK/ha); varying rates of radiation-modified carrageenan (with and without stickers) were laid out in randomized completely block design with three replication. Inorganic RR fertilizer was applied in two splits. Half of full recommended rate (90kg N/ha) and half recommended rate (45kg N/ha) of N fertilizer and all of P and K fertilizer was applied at planting date (0DAT).
The remaining half of N recommended rate was further split and applied equally at 14 DAT at panicle initiation stage (42DAT). Foliar application of varying rates of carrageenan was applied at tillering (15DAT), panicle initiation (40 DAT), and at milking stage (75DAT).
Activity 1. Effect of radiation modified carrageenan on the growth and yield of rice (Experiment 2)
Table 41. Tiller number per hill of NSIC Rc216 as affected by different treatments grown under greenhouse condition (DS2014).
Treatment Tiller number at
harvest
0kg NPK 0ppm 8.00 c
0kg NPK 50ppm 7.67 c
0kg NPK 100ppm 8.33 c
0kg NPK 100ppm (with sticker) 7.67 c 45-20-20kg NPK/ha 0ppm 11.33 bc 45-20-20 kg
NPK/ha
50ppm 12.67 ab
45-20-20 kg NPK/ha
100ppm 11.33 bc
45-20-20 kg NPK/ha
100ppm (with sticker) 11.67 abc
90-40-40 kg NPK/ha
0ppm 14.67 ab
90-40-40 kg NPK/ha
50ppm 15.00 ab
90-40-40 kg NPK/ha
100ppm 15.67 a
90-40-40 kg NPK/ha
100ppm (with sticker) 15.00 ab
• Highest tiller count was obtained in treatment with full recommended rate of fertilizer and 100ppm carrageenan without sticker. However, other treatments with full NPK including those with only full NPK were not significantly different.
• No significant differences can be obtained with treatments without fertilizers.
• Treatment with 50ppm and half NPK produced more tillers compared to the other treatments with half NPK rate.
Table 42. Chlorophyll measurement using SPAD-502 of NSIC Rc216 as affected by different treatments (DS2014).
Treatment 53 DAT 61 DAT 85 DAT
0kg NPK 0ppm 33.60 bc 30.20 a 29.23 a
0kg NPK 50ppm 32.20 c 30.60 a 24.17 a
0kg NPK 100ppm 34.53 abc 31.17 a 26.97 a
0kg NPK 100ppm (with
sticker)
31.63 c 30.17 a 26.20 a
45-20-20kg NPK/ha 0ppm 40.00 a 35.43 a 29.67 a 45-20-20 kg
NPK/ha
50ppm 37.33 abc 30.77 a 28.43 a
45-20-20 kg NPK/ha
100ppm 36.97 abc 31.00 a 27.03 a
45-20-20 kg NPK/ha
100ppm (with sticker)
36.77 abc 35.77 a 27.17 a
90-40-40 kg NPK/ha
0ppm 37.70 abc 31.87 a 27.60 a
90-40-40 kg NPK/ha
50ppm 39.70 ab 33.77 a 30.57 a
90-40-40 kg NPK/ha
100ppm 37.27 abc 32.83 a 28.70 a
90-40-40 kg NPK/ha
100ppm (with sticker)
40.07 a 30.77 a 26.87 a
• Chlorophyll meter (SPAD-502) reading was most affected by NPK application and varying rates of carrageenan application at 53DAT (booting stage).
• At tillering stage, SPAD readings were not significantly affected by NPK application (data not shown).
• At reproductive stage, no significant differences can be obtained from SPAD readings.
Table 43. Grain yield (14% MC) of NSIC Rc216 as influenced by application of two N rates and varying rates of carrageenan (DS2014).
Treatment Yield (14%MC)
0kg NPK 0ppm 2.21 d
0kg NPK 50ppm 2.05 d
0kg NPK 100ppm 2.27 d
0kg NPK 100ppm (with sticker) 2.21 d 45-20-20kg NPK/ha 0ppm 4.57 c 45-20-20 kg
NPK/ha
50ppm 5.93 abc
45-20-20 kg NPK/ha
100ppm 5.05 bc
45-20-20 kg NPK/ha
100ppm (with sticker) 5.62 abc
90-40-40 kg NPK/ha
0ppm 5.82 abc
90-40-40 kg NPK/ha
50ppm 5.81 abc
90-40-40 kg NPK/ha
100ppm 7.51 a
90-40-40 kg NPK/ha
100ppm (with sticker) 7.11 ab
• Plants with full NPK fertilizer produced higher yield compared to those applied with half the recommended of NPK fertilizer.
Additionally, application of carrageenan further boost the yield produced.
• Plants applied with 90-40-40 kg NPK/ha with 100ppm carrageenan without sticker produced grain yield (7.51 t/ha) which is slightly higher than with sticker (7.11 t/ha).
• Plants applied with 45-20-20kg NPK/ha with 100ppm carrageenan with sticker produced higher yield than those without sticker at the same fertilizer rate. However, note that 50ppm with half NPK also increased yield.
• There was no significant effect of treatments with stickers on the yield of rice.
During the wet weason 2014, pot experiments using rice variety NSIC Rc216 were laid out in randomized complete block design with three replications, under greenhouse condition at PhilRice Nueva Ecija. The experiment consisted of 24 treatments for testing: unfertilized treatment, two rates of inorganic fertilizer; 90-40-40kg NPK/ha which is the recommended full rate (Full RR) and 45-20-20kg NPK/ha which is the half recommended fertilizer rate (1/2 RR); and foliar spraying of varying concentrations of radiation-modified carrageenan and commercially available carrageenan formulation, Algafer. Foliar applications were done at tillering (15 DAT) and panicle initiation (45 DAT) for experiment 1 and an additional application at milking stage (75 DAT) for experiment 2. Data for yield at 14% moisture content was obtained and corresponding data analysis was carried out to determine the significance of the treatments.
Highlights:
• Grain yield in experiment 1 was increased by 34% with 7.05g/pot upon application of 200ppm carrageenan over the untreated control which only yielded 5.23g/pot. However, no significant difference was observed with the application of 25ppm which yielded 7.04g/pot, a 34.6% increase over the untreated control. Application of inorganic fertilizer intensified the effect of carrageenan compared to unfertilized treatments.
Application of 200ppm carrageenan with ½ RR increased the yield by 25.6% (17.07g/pot) compared to the treatment with fertilizer alone (13.57g/pot). The application of 200ppm carrageenan under full RR yielded 15% (24.19g/pot) more than fertilizer alone (21.03g/pot). Yields obtained using Algafer did not differ significantly over treatments at unfertilized
condition, comparable to ½ RR alone but yielded lower than the other treatments in full RR.
• Results for experiment 1 showed that using 200ppm
concentration of Carrageenan yielded higher results compared to the unfertilized treatments, ½ RR, and full RR showing its efficiency compared to the other treatments and with the commercially available foliar spray, Algafer.
• Experiment 2 presented no significant differences in grain yield under unfertilized treatments after additional spraying at milking stage (75 DAT). Conversely, application of 100ppm carrageenan boosted the yield by 31.2% (6.86g/pot) over untreated control (5.23g/pot). Addition of inorganic fertilizer at ½ RR increased the yield compared to the untreated control. An increase in yield was observed in plants treated with varying concentrations of carrageenan in combination of the half rate fertilizer. Twenty-five ppm yielded a 28.8%
(17.48g/pot) increase; 75ppm, gained a 26% (17.11g/pot) increase, and lastly, 100ppm had a 27.5% (17.3g/pot) increase compared to ½ RR alone (13.57g/pot). Full rate fertilizer with the addition of 75ppm, 100ppm and 150ppm application generated no significant difference but yielded an increase of 17.8% and 16.4% upon application of 75ppm (25.58g/pot) and 100ppm (25.14 g/pot), respectively. Algafer application did not differ significantly to other treatments at unfertilized treatment, comparable to ½ RR, and yielded lower than other treatments at full RR.
• The second experiment showed varying result from that of experiment 1, showing that lower concentrations of carrageenan, specifically 75ppm and 100ppm, yielded more grains compared to the pots treated with 200ppm.
Figure 44. Grain yield of NSIC Rc216 at 14% moisture content (MC) affected by different treatments applied at mid tillering and panicle initiation for 2014
Wet Season (WS).
Figure 45. NSIC Rc216 grain yield at 14%MC as affected by the different treatments applied at mid tillering, panicle initiation and at milking stage for
2014 Wet Season (WS).
Study 2. Effect of radiation-modified carrageenan and chitosan application