Tidal land could become the foundation of future food security in Indonesia,
specifically for rice farming because it is still widely available with a total
of 20.1 million hectares (LWCADIC, 2014). Increasing
rice productivity in this area will greatly affect the food security and national
economies. However, efforts to increase the production within the area of tidal
land are still difficult due to the natural problems, farmers social and cultural
and the fanaticism of farmers to local cultivars. Flooding after harvest season
in wetlands (Adigbo et al., 2012) or drought
causes the soil to become uncultivatable. So, it is quite difficult to increase
Cropping Intencity (CI) from once an year to more than once an year. One way
to increase rice production in areas which are difficult in adopting CI and
new varieties is ratooning system using new plant type rice ratoon which have
similarities with local cultivars commonly grown by the farmers. Ratoon is an
appropriate technology with low input and has potential to increase rice production
in tidal areas (Adigbo et al., 2012), to improve
the resilience of farmers to climate change (FAO, 2014),
to produce more rice in a narrow area, limited water and low cost (Pinera
and Martin, 2011). In general, rice farmers in tidal wetlands were familiar
to the term of ratoon. Ratoons are plants grow from buds contained in the node
stubble or rice stalks left at harvest (Harrell et al.,
2009). However, not many farmers use it as a source of income because yield
of ratoon is usually low. Through the introduction of the new ratooning varieties
with grain quality similar to the local cultivars, the effort to increase production
will be much easier.
Crosses of local varieties to improve ratooning trait have been implemented
and the lines still need to be tested for their ratooning ability. Susilawati
et al. (2012) reported that the yield of 5 ratoon rice genotypes
tested in the tidal area ranged from 38.1-56.6% of the main crop yield.
Some characters like: Fast growth and vigor, culm thickness, early maturity
and stay green leaves may correlate with the characters of ratoon and controlled
genetically but the most dominant factor influencing yield of ratoon is unknown.
Culm thickness correlated with high levels of carbohydrates in the culm. Carbohydrates
reserve can induce ratoon regeneration ability better, produces more ratoon
tiller and higher grain yield (Palchamy and Purushothaman,
1988; Ichii and Ogaya, 1985). There was variation
in the ratooning ability between cultivars as a result of genetic control (Bahar
and De Datta, 1977) and environmental influences.
New plant type rice has better vegetative growth and has yield ratoon higher
than other varieties but hybrid varieties have better vigor than inbreed (Susilawati
et al., 2010). Out of the 30 varieties/lines tested for their ratooning
ability, only 3 lines which have the potential ratoon in terms of plant vigor
(Oad and Cruz, 2002). Duration of growth is one of the
genetic trait that have significant effect on the ratooning ability and yields
(Vergara et al., 1988).
Differences of varieties are also associated with the origin of ratoon tillers
emergence on rice straw. Tillers can emerge from all the node on the trunk or
from lower node or from a certain number of nodes. Many findings indicated that
ratoon crop would produce better yield if the main crop culm is cut by leaving
2-3 nodes. Variations in soil, water, light and temperature greatly affect the
ratooning ability (Krishnamurthy, 1989). Physiological
aspects such as the rate of net photosynthesis at different phases of grain
filling among cultivars, causing yields of ratoon different from each other
(Zhang et al., 2011). Therefore, selection in
the ratoon genotypes might obtain good ratoon ideotype.
On the other hand, the ratooning ability of varieties greatly influenced by
cultivation techniques. Liu et al. (2012) found
transplanting system, generates better ratoon than seeding system or direct
seeding. Unfortunately, to date, information about screening of rice genotypes
that able to produce ratoon in tidal land is still very limited. Therefore,
the objective of the present study was to investigate the ratooning variability
on various genotypes of rice, to develop selection criteria for ratoon characteristics
that correlate with ratooning ability and to determine the potential yield of
ratoon in tidal land. Selection was directed towards rice genotypes possessing
high ratoon productivity.
MATERIALS AND METHODS
Screening genotype: There were 68 rice genotypes tested, 16 local varieties:
Siam Linggis, Siam Mutiara, Brenti, Siam Unus, Siam Kuning, Beras Merah, Siam
Narsis, Siam Jerurut, Karya Pelalawan, Cekau F10, Cekau F14, Cekau F32, Cekau
F33, Cekau F37, Cekau A, Korea N; 2 hybrid varieties: Hipa 8 and Hipa 10; 39
inbred lines: IPB97-F-13-1-1, IPB107-F-95, IPB107-F-14-4-1, IPB107-F-14-5-1,
IPB107-F-18-4-DJ-1, IPB Batola 6R, Inpago IPB 8G, IPB 4S, IPB107-F-7-3-1, IPB107-F-13-1,
IPB107-F-40E-1, IPB107F-5-5-1, IPB107-F-20-5-1, IPB107-F-34-1, IPB107-F-77-3,
IPB107-F-10-1, IPB BATOLA 5R, IPB117-F-14-2-1, IPB105-F-20-1, IPB 3S, IPB107-F-60-1,
IPB107-F-18-4-1, IPB107-F-18, IPB107-F-16-5, IPB107-F-127, IPB107-F-135, IR
09F164, IR 09F159, HHZ5-SAL10-DT2-DT1, IR 09F229, IR 09F250, IR 09F496, HHZ5-SAL10-DT1-DT1,
IR 09F504, IRRI 119, IPB107-F-65-3-1, PSBRC 82 Sub1, BP1031F-PN-25-2-4-KN-2,
Ciherang Sub1; 10 inbred varieties: IPB 1R Dadahup; Margasari; IPB 2R Bakumpai;
Inpara 1; Inpara 2; Inpara 3; Gilirang; Cimelati; Ciapus; Inpari 2; and 1 new
plant type: Fatmawati. Genetic materials were obtained from the Bogor Agricultural
University, Indonesian Center for Rice Research, Local Kalimantan and Local
Screening of rice genotypes was conducted in Bogor, West Java Province from
October 2011 to May 2012. Genotypes were planted using a randomized complete
block design with three replicates each. The genotypes were planted four rows
in 5 m with spacing of 20x20 cm when seedlings were 20 days old. Each hill was
planted with one seedling.
Basic fertilizer based on result of soil analysis were Urea 100 kg ha-1,
TSP 150 kg ha-1 and KCl 50 kg ha-1, given in conjunction
with Furadan® 3G 16
kg ha-1 one day before transplanting. Supplementary fertilizer of
Urea 50 kg ha-1 based on leaf color chart and KCl 50 kg ha-1
were given at 35 Days After Transplanting (DAT). Control of pests and diseases
is done in an integrated manner. Plants protected by trap barrier system to
deter rats and experimental area covered with bird nets.
Harvesting is done after 95% panicle ripening by cutting at a height of 10
cm from the soil surface (Petroudi et al., 2011).
One day after harvest, irrigated land as high as 3 cm and sown Urea 50 kg ha-1,
TSP 30 kg ha-1 and KCl 25 kg ha-1. Maintenance of ratoon
plants was similar to those conducted for main crop.
Of the 68 genotypes tested, selection was made for genotypes that have good
ratoon production and one for worst ratoon genotypes. Selection is done as well
against some of the characters are correlated with ratooning ability. The plant
performance observed by scale categories modified from IRRI
(1988): 1 = Very poor, 2 = Poor, 3 = Somewhat good, 4 = Good and 5 = Very
good. Harvest uniformity observed using categories: 5 = Uniform, 3 = Somewhat
uniform and 1 = Not uniform.
Evaluation of ratooning ability: Selected genotypes were tested in the
tidal acid sulphate soil area with type B of flood water in Pulang Pisau District
of Central Kalimantan Province from December 2012 to May 2013. The experiment
was designed according to randomized complete block design with three replicates.
Irrigation system follows the pattern of the ebb and flow of the water in the
river, the water was allowed in and out naturally, except at the time of fertilization,
water was held in the paddy fields for 7 days.
Statistical analysis: Data was analyzed using ANOVA random model for
one season in one location. Genetic variability of observed characters was calculated
by Anderson and Bancroft (1952) with the equation:
Genetic variability is broad when σ2G≥2(σG)
and narrow when σ2G<2(σG). The
relationship between growth and yield variables were observed, calculated using
Pearson correlation analysis. The amount of direct and indirect influence of
these variables on the yield of ratoon calculated using path analysis according
to Singh and Choudhary (1979). The best genotype in screening
determined by highest index value with equation:
Index = W1X1+W2X2+W3X3+
||Direct effect value of main crop character to the yield of
||Mean value of main crop character
The data of evaluation of ratoon genotype on tidal land was analyzed by analysis
of variance followed by Duncan Multiple Range Test. Genotypes that produce high
yield ratoon chosen as type ratoon specific for tidal land.
Variability of agronomic characters: The main crop characters and yield
of ratoon were observed, have a broad phenotypic variability except the culm
thickness. Character, leaf color, culm diameter, number of effective tillers,
number of tillers 30 Days After Transplanting (DAT) and clump weights 30 DAT
has a narrow genetic variability (Table 1). Phenotype and
genetic variability character of main crop productivity, plant height 30 DAT
and the number of effective tillers were broad.
Performance of main crops: Out of the 68 genotypes tested, 17 genotypes
were found to be high yielding (Table 2). The highest yield
of main crop was obtained from HIPA 10 equivalent 5.88 t ha-1 grain
yield but from the overall appearance of the plant, genotype HIPA 10 was not
the best because the leaves of HIPA 10 have been attacked by brown spots diseases
and the culm diameter was small so the plant looks weak. This type of growth
will produce vulnerable ratoon to disease and weak.. The out of the 17 genotypes
only IPB107-F-14-4-1, IPB107-F-14-5-1 and IPB Batola 6R gave high yield and
showed good performance. Genotype Inpago IPB 8G was lower than the 17 genotypes
but showed a very good performance for stay green leaves which may be important
for ratoon. Based on the productivity of main crops there were three genotypes
which showed high productivity i.d. HIPA 8, IPB107-F-18 and IPB107-F-65-3-1
with productivity 24.25, 24.06 and 23.96 g per clump grain yield, respectively.
||Phenotypic varians, genetic variability and heritability characters
of 68 rice genotype
||Main crops performance of best 17 rice genotypes selected
based on the grain productivity of main crops in the screening of 68 genotypes,
Performance of ratoon: There was decrease in appearance of ratoon crop
such become shorter than main crop, smaller clumps, smaller culm, early maturity,
shorter leaves and panicles and yield was lower but other characters such as
the position of the leaves, leaf color and culm erectness were same to the main
crop. There was considerable variation in ratooning ability between genotypes.
Genotype Siam Narsis, Inpara 2, Cekou A and Korea N did not produce ratoon at
all. Instead there were ten ratoon genotypes capable to producing number of
living hill at least 50% of the population of main crops, namely: IPB97-F-13-1-1,
IPB 4S, IPB107-F-20-5-1, IPB107-F-77-3, IPB 3S, IPB107-F-18-4-1, IPB107-F-16-5,
Cekau F10, IR 09F504 and Fatmawati. IPB107-F-20-5-1 produced high percentage
of living clump of ratoon but was succebtible to attacked by bacterial leaf
blight, sheath blight and neck blast so that the appearance of IPB107-F-20-5-1
was very poor (Table 3). Genotype IPB97-F-13-1-1 has high
level of empty grains in the main crop which was due to photosynthate for grain
filling into energy to form buds ratoon. Therefore ratoon of IPB97-F-13-1-1
appeared before harvest.
Several factors caused poor ratoon performance were number of clumps do not
have seeds, dwarf clump, clump attacked by bacterial leaf blight or blast, lodging
clumps, origin of tillers and inequality in time of harvest. A large number
of unproductive clumps associated with the emergence of dwarfs clumps resemble
grass as in Siam Narsis. This genotype was only able to grow 29.8% ratoon that
all were dwarf and subsequently died before the generative phase (Table
The number of lodging clumps was very important in plant population appearance
and productivity of genotype. Lodging clumps on ratoon plants most commonly
found in genotype IR 09F496, Cekau F10 and IR 09F504 compared to the living
clumps of ratoon respectively 25.6, 24.1 and 16.8%. The lodging clumps associated
to the origin of ratoon buds, from the node of culm above ground (nodal), rarely
found on tillers grown under soil surface (basalt).
Genotypes that produce ratoon crop which ripen simultaneously are ideal idiotype
for ratooning. The best level of uniformity in maturity showed by genotype IPB
4S and IPB BATOLA 5R.
||Ratoon performance of 68 rice genotypes in Bogor, 2012
Genotypes that were classified as somewhat uniform were: IPB97-F-13-1-1, IPB107-F-14-4-1,
IPB107-F-14-5-1, IPB Batola 6R, Inpago IPB 8G, IPB 3S and IPB107-F-18.
Genotype IPB107-F-18 and Siam Kuning mature at the age of 53 days after the
main crop harvested (DAH). Furthermore, there were several genotypes can already
harvested less than 60 days since the main crops harvested, namely: IPB107-F-34-1,
IR 09F496, IPB107-F-40E-1, IPB117-F-14-2, Inpari 2, IPB BATOLA 5R, IPB 3S, IRRI
119 and Siam Linggis. The longest maturity of ratoon was found in IR 09F164
which was harvested 89 days after the main crop harvest.
Relationships between main crop characters and productivity of ratoon: The
main crops appearance were generally reflected in ratoon, therefore selection
for main crop ideotype was important for good ratoon. Genotypes that have large
culm will produce no dwarf ratoon. Genotype Siam Narsis which has slender and
tall culm did not produce ratoon. Tillers grew from the Siam Narsis stubble
were dwarf and ineffective. Unlike the genotype IPB107-F-14-4-1 that had culm
diameter 0.62 cm produce good ratoon yield.
There was a tendency that vigorous plants as shown in plant height and clump
weight at 30 DAT had good ratooning ability with r values of 0.422 and 0.415,
respectively. Ratoon productivity tends to be high in genotypes with high clump
weight and plant height at 30 DAT.
Total of 73% of stay green plants (the color scale of leaves at harvest >
3.5) resulted in high ratoon productivity or at least 7.5 g clump-1
grain yield. Furthermore, as many as 81% of non stay green plant (the color
scale of leaves at harvest is 2) resulted in low productivity <7.5 g clump-1
Analysis of correlation between main crop characters and productivity of ratoon
showed that productivity, color of leaves, culm diameter, culm wall thickness,
plant height at 30 DAT and clump weights at 30 DAT of main crop significantly
correlated to the productivity of ratoon. The main crop characters affect that
strongly correlate to productivity of ratoon was culm diameter (r = 0.72**),
followed by plant height 30 DAT (r = 0.42**), clump weight 30 DAT (r = 0.41**),
productivity of main crops (r = 0.33**) and color of leaves (r = 0.22**). The
larger plant culm, the better ratoon generated.
The correlation coefficient of main crop productivity and ratoon productivity
was 0.33 while the direct effect was only 0.05. Character of plant height 30
DAT also had a correlation coefficient greater than the value of its direct
effect (Fig. 1). Among the various characters observed, the
character of culm diameter has the highest correlation to productivity of ratoon
with a strong correlation coefficient 0.72 and direct effect 0.62.
Selection of the best genotype based on main crop character and ratoon:
Selection of genotypes based on many characters at once, need consider the
value of variance components represented by F value in Anova is very significant,
high correlation between the characters that will be used as selection criteria
with the yield and a fairly high heritability. According to McWhiter
(1979), the criterion to estimates value of heritability are as follows:
high heritability if H> 0.5; medium heritability was 0.2<H<0.5, low
heritability H<0.2. The main crop traits such as productivity, color of leaves
at harvest, culm diameter, culm thickness, plant height at 30 DAT and clump
weights at 30 DAT had F-value very significant and very significant correlated
to productivity of ratoon (Table 4), so the main crop variables
have three requirements as the selection criteria.
Direct and indirect effects of the seven
main crop characters to the productivity of ratoon. RP: Ratoon productivity,
MCP: Main crop productivity, CL: Color of leaf, SD: Culm diameter, ST:
Culm thickness, H30: Plant height 30 DAT, NPT: No. of effective tiller,
CW30: Clump weight 30 DAT
||Coefficient of variation correlation of main crop characters
to ratoon yield
|ns: Not significant, **Significant at p>0.5
The six main crop variables above used as selection criteria to select rice
genotypes with ratoon potential by index and selected nine genotypes, namely:
IPB97-F-13-1-1, IPB107-F-14-4-1, IPB107-F-14-5-1, IPB Batola 6R, Inpago IPB
8G, IPB 4S, IPB BATOLA 5R, IPB 3S and IPB107-F-18 (Table 5).
In addition, characters of ratoon crop such as productivity of ratoon, the difference
of main crop to ratoon productivity <60% and uniform maturity (Table
6) tighten the selection so that the selected genotypes were best ratoon
genotype. Nine genotypes were selected as ratoon rice by using indeks selection,
Some criteria of ratoon genotype desired in this study were those with ratoon
productivity above 7.5 g clump-1 or at least 1.5 t ha-1
of Dry Milled Grain (DMG), new type rice plant, difference of yield of main
crop and ratoon not more than 60% or yield of ratoon at least 40% of the main
crop with uniform maturity. Genotype IPB97-F-13-1-1 has small a difference in
productivity between ratoon and the main crop (8.9%), followed by IPB 4S (20.3%)
and IPB 3S (20%). All three genotypes were new plant type rice.
||Index selection of nine ratoon genotype based on the main
crop characters and direct effect of main crop characters to productivity
||Productivity of nine ratoon genotype, difference of main crop
and ratoon productivity and uniform maturiy
Yield trials of ratoon genotypes in tidal swamp environment: Evaluation
of selected genotypes in tidal acid sulphate soil with type B water flooding
showed significant effect of genotype on the yield of main crop, yield of ratoon,
as well as the main crop + ratoon. All genotypes showed lower growth and yield
compared to the yield in Bogor. These low yield was related to high abiotic
stresses in acid soil with pH 4.08, high iron 617 mg kg-1 Fe and
pyrite 1032 mg kg-1 FeS2. Lightest bronzing symptoms occured
in Inpara 2 and heaviest in genotype IPB107-F-14-5-1 and IPB BATOLA 5R due to
high Fe concentration. Bronzing was worse with increasing age of the plant.
Genotype Inpara 2 produced 3.52 t ha-1 of dry milled grain (dmg)
from the main crop, the highest among the other genotypes but only produce 0.53
t ha-1 dmg from ratoon. Other genotypes produced less grain from
the main crop but ratoon can produce up to more than 50% of the main crop yields
so that the total main crop yields and ratoon can reach 4 t ha-1.
Genotype IPB97-F-13-1-1, IPB107-F-14-4-1, IPB 4S and IPB 3S able to maintain
appearances until harvest with little missing hills and panicle mature simultaneously
(Table 7). This situation cannot be separated from their tolerance
to some major stress in acid sulphate soil.
The total yield of main crop + ratoon of genotype IPB97-F-13-1-1, IPB107-F-14-4-1,
IPB Batola 6R, Inpago IPB 8G, IPB 4S, IPB 3S and IPB107-F-18 did not significantly
different to the yield of main crop of Inpara 2. The yield of main crop genotype
IPB97-F-13-1-1 and IPB 4S were 2.85 and 2.82 t ha-1.
|| Yield of genotype ratoon in tidal acid sulphate soil area,
Pulang Pisau (2012-2013)
Performance of ratoons and relationship between main crop character and productivity
of ratoon: There were variation in ratooning ability between genotypes known
as genetic influences but variation of ratooning ability in genotype was environmental
influences. Ratooning ability is genetic but the environment is very strong
intervene. Missing hills was found in all genotypes in different number. Genotype
IPB 3S produce lower missing hill 22.8%. This relate to the genotype ability
to maintain ratoon buds viability on the culm, resistance to disease and availability
of food reserves in the culm.
Ratoon height was shorter than the main crop and only 11 genotypes were able
to achieve = 80 cm. Ratoon height associated to the origin of tiller from nodal
or basalt. Almost all high tillers were growing from basalt. According to Yang
et al. (2011), the plants of ratoon have to grow taller to extend
the period of growth so grain yield can be achieved. The faster increase in
height and weight of plants in vegetative phase can be used as selection criteria
for ratoon rice (r = 0.4). One feature of a plant grows rapidly was the rate
of increase node number quickly. Plants have rapid rate of node increase number
will have more tillers and panicles and weight of leaves, culms and panicles
higher. The number of nodes in the main culm has a significant positive direct
effect on weight of culm and maximum tiller number (Samonte
et al., 2006). High culm weights reflecting the large culm and dense.
Such culm would produce good ratoon. It was related to optimal function of roots
and leaves so the plants can utilize all resources properly to accumulate biomass.
The good character of both roots and leaves can give positive effect on ratoon.
According to Zhang et al. (2010), increasing
the activity of main crop roots after heading is important to produce high yield
ratoon based on the high ability of buds to survive.
Cultivars with high dry weight had high nutrients in the culm. There were differences
in nutrient content the main crop between cultivars (Nakano
et al., 2009). Morphological appearance of main crops such as large
culm and green, dense clump and leaves and stumps remain vigor and green were
the character determines the ratooning ability (Susilawati
et al., 2010).
Nitrogen plays an important role in breaking the tiller bud from dormancy and
significantly promoted growth. The growth during the ripening process is enhanced
by the high concentration of N in the leaves. This is the reason for the importance
of stay green leaf trait to produce a good ratun (Dingkuhn
et al., 1991). Color of the leaves at harvest can used as one determinant
of good ratoon generated. The main crop leaves are still green at harvest indicates
there are many Nitrogen (N) in the leaves, culm and node.
Variation in ratoon between genotypes may be associated to variations in N
plant as a result of genetic different. Majority (73%) stay green leaves genotype
produce high productivity of ratoon. This is contrast to Arumugachamy
et al. (1990) who reported that the aging of main crop leaves at
harvest and carbohydrate content in the main culm of the plant does not significantly
affect the yield of ratoon. The IPB 4S showed good performance, stay green leaves,
large culm diameter 0.597 cm, vigorous and highest number of fresh culms (8.67
rods). This is consistent to Balasubramanian et al.
(1992) who states that delays the aging of leaves, high levels of carbohydrates
in the culm and the big culm were some reason for the high number of tillers
ratoon. High productivity of main crops did not guarantee for high productivity
of ratoon. Many genotypes rank changed based on the yield of ratoon when compared
to the same genotype ranked based on the yield of main crop. However, this character
has a broad genetic variability and positively correlated with the yield of
ratoon so although can not be used as the sole criterion, selection the main
crop for high yield and good ratoon still can be done freely. Genotype HIPA
10 and IPB107-F-65-3-1 produced 5.88 and 5.6 t ha-1 grain yield from
main crop but only 492 kg ha-1 and 45.8 kg ha-1 grain
yield from ratoon, respectively (Table 2). In addition to
genetic factors, it was believed relate to the availability of nutrients for
main crop growth phase. Islam et al. (2008) reported
that the highest yield of main crops produced by fertilization of 120 kg ha-1
N, 65 kg ha-1 P2O5, 70 kg ha-1 K2O,
13 kg ha-1 S and 4 kg ha-1 Zn. But in the ratoon crop,
the highest yield was obtained by fertilization 150 kg ha-1 N, 85
kg ha-1 P2O5, 90 kg ha-1 K2O,
13 kg ha-1 S and 4 kg ha-1 Zn. This suggests that to produce
a good ratoon, fertilizer should given over the main crop need so that the plant
can save it for ratoon growth.
The number of main crop tillers at 30 DAT was not significantly correlated
to ratoon productivity. Many lines produce many tillers in main crop but their
size is small or slim so cannot produce ratoon as Siam Narsis has. According
to Yang et al. (2004), the most influential
variable on yield of ratoon is the number of effective tillers of ratoon but
in the main crop, the variable number of grains per panicle more influence on
the yield than the number of effective tiller. According to Cai
et al. (2011) the ability of varieties to produce different number
of tillers, affect to panicle number of ratoon crop. Therefore, the main crop
of ratoon varieties must have high tillering ability.
In this study, the most strong main crop characters affect productivity of
ratoon were culm diameter (r = 0.72). The larger plant culm, the better ratoon
generated. Therefore, according to Balasubramanian et
al. (1992), the diameter of culm of the main crop can be used as selection
criteria for rice ratoon.
The small direct effect between main crop and ratoon productivity showed that
main crop productivity less effective as a selection criterion for rice ratoon.
Correlation coefficient of main crop color of leaves with ratoon productivity
was 0.22 (positive) while its direct effect was only 0.047 (negative). This
is meaning that not direct effect which causes the correlations rather indirect
effect. Thus the character cannot used as sole selection criteria in the direct
selection because it will not effective. Oad et al.
(2002) were report that the parameters of ratoon have low positive direct
The small difference value between correlation (0.72) and direct effect (0.62)
character main crop culm diameter and productivity of ratoon, meaning the correlation
describes the real relationship and direct selection will effective through
culm diameter trait of the main crop. According to Wu et
al. (2011), the large culm trait usually exhibited greater plant size,
larger culm diameter and lower number of tillers. This character is important
because it relates to lodging resistance, biomass accumulation, flag leaf length
and width, larger leaf vascular bundles, more culm vascular bundles, higher
transpiration rate, photosynthetic efficiency and transport apoplastik ability.
Selection of genotypes can based on the high yield of ratoon, many effective
tillers, many panicles per hill, long panicle and high-ranking ratoon (Oad
et al., 2002). If there are two characters that are not correlated
but both characters have a significant direct effect on the characters that
directly affect grain yield, so the both characters can used as selection criteria
for yield (Samonte et al., 2006).
The contribution of each main crop character separately to the ratoon productivity
was relatively small. The best ratoon obtained when several characters were
present together. Genotype IPB107-F-14-4-1 have highest productivity ratoon
appears to have also some important characters like green leaves at harvest,
large culm diameter 0.63 cm, culm thickness 0.09 cm, number of effective tillers
10.11, vigorous and showed good performance. Genotype IPB107-F-14-4-1 followed
by HIPA 8 in ratoon productivity and its
main crop productivity highest among all genotypes tested. HIPA 8 also has some
good characters are present as well, such as: Good performance, culm diameter
0.61 cm, clumps weight 30 DAT 6.55 g clump-1 and number of effective
tillers 12.22. Genotype Inpago IPB 8G was the best looking, most green leaf
color (dark green), large culm diameter 0.596 cm, vigorous and had many fresh
culms at harvest. IPB-97-20 showed good performance, green leaf, culm diameter
0.597, vigorous and highest number of fresh culm 8.67. In contrast, genotype
Siam Narsis have not all the superior characters. Genotype Siam Narsis had small
culm diameter that is 0.451 cm, senescence leaves at harvest time, not vigorous,
tall slender plant and performance not good. Nevertheless Siam Narsis had thick
culm wall 0.068 cm, the only one superior character it has. Similar to Siam
narsis there were genotype Cekau A and Korea N.
Selection of the best genotype based on main crop character and ratoon:
Ratoon productivity is the main purpose and the most important criteria
in rice ratoon selection. Ratoon productivity has a wide genetic variability
so that selection for high productivity of rice ratoon can do on this character.
These results are similar to Ichii and Kuwada who demonstrate considerable ability
to generate ratoon between genotypes (Ichii and Kuwada,
1981), genotype effect on the yield of ratoon (Susilawati
et al., 2012) or ratooning ability was different between varieties
(Balasubramanian et al., 1992). Productivity
illustrates the potential of each individual genotype to produce ratoon. Unlike
the character productivity, character yield per unit area is more real but often
do not illustrate the potential genotype because the effect of genotype x environmental
is large so there are many missing hills. Genotype IPB107-F-14-4-1 had a great
ratoon potential and high productivity (14.34 g clump-1) but the
real yields only 0.53 t ha-1. The low yield obtained IPB107-F-14-4-1
due to many clumps missed. According to Turner and Fund (1993),
the factors affect yield of ratoon is not quite clear known. However, missing
hill is not genetic but environmentally. Therefore, such genotypes need to be
tested in different agro-ecosystems.
In addition high productivity of ratoon, uniformity to mature is also an important
criterion for ratoon. The simultaneously time to harvest produce rice yield
with a low percentage of green grains, save labor and low harvest costs.
Farming system of ratoon expect the accumulation yield from main crop and ratoon
is high. High yield will obtained if the productivity of main crops and ratoon
equally high. Therefore, the selection can directed to the genotypes have small
difference in main crop and ratoon productivity. Adigbo
et al. (2012) reported that the yield of the main crop was 5.0-7.3
t ha-1 with the yields of ratoon between 1.0-4.7 t ha-1
dry grain or yield of ratoon can reach 64% of the main crop.
Yield trials ratoon genotypes in tidal environment: The low yields
of all genotype planted in tidal land were related to abiotic stresses particularly
high acid soil (pH 4.08), iron (617 mg kg-1 Fe) and pyrite (1032
mg kg-1 FeS2). According to Kampfenkel
and Montagu (1995), under oxidative conditions, pyrite oxidizes so harmful
to plants and Fe toxicity causes oxidative stress. All plants showed symptoms
of bronzing which according to Romheld and Nikolic (2006)
is due to Fe toxicity. Bronzing characterized by rust spots or small brown stain
spreading on leaf, older leaves fall prematurely and roots turn into brown.
The decrease in rice yields due to iron poisoning range from 40-100% (Aung,
2006). The development of plants in acid sulfate soil is focused on adaptation
to Fe, Al and acidity (Wu et al., 2014; Shamshuddin
et al., 2013; Kang et al., 2010;
Sahrawat, 2010). Although yield of main crop genotype
IPB97-F-13-1-1 and IPB 4S relatively low if compared to the yield obtained when
the genotype was grown on a better environment in Bogor but the narrow difference
yields of main crop and ratoon promising that genotypes potential as a new type
ratoon paddy. Repair tidal environment with cultivation techniques are expected
to improve the yields of main crop and ratoon. Thus the genotypes IPB97-F-13-1-1,
IPB107-F-14-4-1, IPB 4S and IPB 3S were potential as rice ratoon for tidal swamp
area that is classified as type B and acid sulfate soil.
The ability of each genotype to produce ratoon is varying widely. Selection
can be done using a secondary character, i.e., culm diameter, fast growth and
vigor, stay green leaf, lot number of effective tillers and high productivity
of main crops. By using multiple selection criteria at once, screened nine genotypes
are potentially as rice ratoon IPB97-F-13-1-1, IPB107-F-14-4-1, IPB107-F-14-5-1,
IPB Batola 6R, Inpago IPB 8G, IPB 4S, IPB BATOLA 5R, IPB 3S and IPB107-F-18.
Of the nine genotypes, only IPB97-F-13-1-1, IPB107-F-14-4-1, IPB 4S and IPB
3S capable to produce yield of ratoon at least 1.5 t ha-1 dry milled
grain or increasing the yield over 50% of the main crop when tested in suboptimal
tidal area type B and acid sulphate soil, thus the four genotypes can be used
as ratoon rice in tidal land.
The research activities were funded by the IPB I-MHERE program of Directorate
General of Higher Education, Ministry of Education and Culture 2012 contract
No. 14/IT3.24/SPP/I-MHERE/2012, Competence Research Award 2013 contract No.
035/SP2H/PL/Dit.Litabmas/V/2013 to HA, Indonesian Agency for Agricultural Research
and Development, Ministry of Agriculture through Ph.D scholarship and The Assessment
Institute of Agricultural Technology of Riau Province, Republic Indonesia, to