Effects of single and combined inoculation of plant growth promoting rhizobacteria on growth performance of paddy (Oryza sativa L.) under glasshouse and field conditions
Rice (Oryza sativa L.) is a staple food in Malaysia grown over 708,148 hectares in various granary areas of Malaysia. In 2016, the average rice production in Malaysia was 2.252 million tons. As the population of Malaysia increases from the current number of 31.2 million, the rice demand also incr...
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| Format: | Thesis |
| Language: | English |
| Published: |
2018
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/83945/1/FP%202018%20102%20-%20IR.pdf |
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| Summary: | Rice (Oryza sativa L.) is a staple food in Malaysia grown over 708,148 hectares
in various granary areas of Malaysia. In 2016, the average rice production in
Malaysia was 2.252 million tons. As the population of Malaysia increases from
the current number of 31.2 million, the rice demand also increases. However,
Malaysia is only able to achieve 71.2% self-sufficiency level (SSL). Thus,
Malaysia has to import rice from other countries, requiring higher productivity in
limited granary areas to fulfill domestic demand. A potential solution to this
problem is by increasing the usage of plant growth promoting rhizobacteria
(PGPR) as a biofertilizer to enhance the productivity and reduced
environmental problems caused by application of chemical fertilizers. The
objectives of this study were to study the interaction effects of single and
combined inoculations of PGPR using in vitro assay studies, effects on rice
growth and development in glasshouse experiments and effects on rice yield,
biomass and nutrient uptake in a field experiment. Determination of panicle
breaking strength to minimize panicle grain shattering under field experiments
was also conducted in this study. PGPR used in this study were Bacillus
pumilus GM118 and Bacillus subtillis UPMB10 which act as phosphate
solubilizing bacteria (PSB) and nitrogen fixing bacteria (NFB), respectively. B.
pumilus GM118 and B. subtillis UPMB10 growth population trends, ability to fix
nitrogen and solubilize phosphate on three different selective media and
production of indole-3-acetic acid (IAA) were conducted in vitro assay. Four
treatments of PGPR with different fertilizers treatments (including control) were
laid out in a randomized complete block design (RCBD) with four replications conducted in a glasshouse at Ladang 10, Faculty of Agriculture, Universiti
Putra Malaysia. The treatments were as follows: T1: control N0K0; T2: N0K90;
T3: N40K30; T4: N40K60; T5: N80K30; T6: N80K60; T7: N120K0 and T8:
N120K90 in the present/absent of single and combined inoculations of B.
pumilus GM118 and B. subtilis UPMB10. N and K in the treatments refer to the
amount of nitrogen and potassium, respectively. The paddy variety used in
glasshouse experiment was MR263 and it was planted using 35 L buckets
containing 15 kg of paddy soil. Meanwhile, the field experiment was conducted
in Kemasin-Semerak Integrated Agricultural Development Area (IADA),
Kelantan. Four treatments were applied in IADA Kemasin-Semerak: T1: control
(without bacterial inoculation); T2: single inoculation of B. pumilus GM118; T3:
single inoculation of B. subtilis UPMB10 and T4: combined inoculations of B.
pumilus GM118 and B. subtilis UPMB10. Normal fertilization practices were
used in these plots. All data were analyzed statistically using SAS Software
Program (Version 9.3) and treatment means were compared using Duncan
Multiple Range Test (P < 0.05). In vitro assay indicated that combined
inoculations of B. pumilus GM118 and B. subtilis UPMB10 produced the
shortest generation times (14.4 minutes) for cells doubling compared to single
inoculations of B. pumilus GM118 (36.1 minutes) and B. subtilis UPMB10 (24.1
minutes). However, single inoculation of B. subtilis UPMB10 is able to produce
more IAA (63.8 μg/mL) compared to combined inoculations of B. pumilus
GM118 and B. subtilis UPMB10 (50.1 μg/mL). Combined inoculations of B.
pumilus GM118 and B. subtilis UPMB10 produced the highest grain yield
(33%), followed by single inoculations of B. subtilis UPMB10 (29%) and B.
pumilus GM118 (23%) as compared to the control in the glasshouse
experiment. B. pumilus GM118 showed the highest N contents (15%) while
combined inoculations of B. pumilus GM118 and B. subtilis UPMB10 showed
the highest K content (16%) compared to control. Detachment of the grain
panicle from the pedicle required the highest force for paddy inoculated with
single inoculation of B. subtilis UPMB10 (11%) and followed by combined
inoculations of B. pumilus GM118 and B. subtilis UPMB10 (8%) as compared
to the control. In the field experiment, both single and combined inoculations of
B. pumilus GM118 and B. subtilis UPMB10 showed significant difference in
grain yield and biomass. In grain yield, B. pumilus GM118 produced 40%, B.
subtilis UPMB10 (61%) and combined inoculations (61%) higher compared to
the control. For biomass production, B. pumilus GM118 produced 33%, B.
subtilis UPMB10 (42%) and combined inoculations of both (40%) higher
compared to the control. IADA Kemasin-Semerak study showed that single
inoculation of B. pumilus GM118 was able to increase 44% and 126% of plant
N and P uptake while B. subtilis UPMB10 was able to increase 30% of plant K
uptake compared to control, respectively.
This study indicated that co-inoculation having beneficial multi-mechanism of
fixing nitrogen, solubilizing phosphate and producing IAA, gave the optimum
performance in both glasshouse and field studies. This study proves that
inoculation of selected PGPR can enhance rice plant yield, biomass, nutrient
uptake and reduce postharvest losses due to grain shattering. The results
showed the potential use of combined inoculations of B. pumilus GM118 and B.
subtilis UPMB10 as biofertilizer with multiple beneficial characteristics that can
increase rice productivity in the granary areas of Malaysia. |
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