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INSECT PESTS IN RATOON RICE 203The increase of GLH on the wet-seeded plots could be attributed to densitydependence. In wet-seeded plots, there was more plant surface to exploit, offeringless crowded conditions than in transplanted plots. Continuous flooding alsosignificantly affected GLH numbers. More GLH were attracted to an aquaticenvironment. Ghose et al (9) noted more GLH in ill-drained habitats.Like the GLH, WBPH numbers peaked at the late vegetative stage, thendeclined rapidly, regardless of planting method (Fig. 2, 3). Even though low levels ofWBPH occurred on the second crop, significantly fewer occurred on the ratoon thanon the seeded crop (Table 1). Seeding method or water regime had no effect onWBPH numbers.The transplanted main crop developed higher BPH numbers than the wetseededmain crop, but populations markedly declined with plant age in both seedingmethods (Fig. 2, 3). BPH numbers in ratoon and seeded second crops wereextremely low, which may explain why no significant differences were found(Table 1).Natural enemy population dynamicsSpider numbers closely tracked GLH and planthopper numbers in the main crop.Hopper numbers rose slowly on vegetative rice, but second generations showed arapid increase. Spiders increased in number during the reproductive stage (Fig. 2, 3).Hunting spiders were twice as abundant on the main crop as were space-web spidersand five times more prevalent than orb-web spiders. The rank order of spiderabundance on the main crop carried over to the ratoon, where spiders were moreabundant than on the seeded second crop. The ratoon, being undisturbed afterharvest of the main crop, was a refuge for spiders. It is also highly probable that thespiders foraged from the ratooned plots to the seeded second crop plots in responseto the presence of more prey, explaining why hopper numbers in general were low onall second crops (30).The hunting spiders were dominated by Lycosa pseudoannulata, whichmaintained an even population level throughout the ratoon crop. Space-web spiderAtypena (= Callifrichia) formosana numbers declined slightly as the ratoonmatured. Because it makes its webs at the base of tillers, A. formosana and the highlymobile hunting spiders can readily colonize a new crop or remain unaffected duringharvest and growth of a ratoon.Orb-web Tetragnatha spp. and Dyschiriognatha sp. spider numbers werelowest on the ratoon. They were more devastated during harvest of the main cropthan the other groups because they need a tall crop from which to suspend theirwebs. These spiders normally become abundant during later growth stages. Theydeclined in numbers at harvest of the main crop, when hoppers had dispersed tocolonize younger crops.Spider numbers did not significantly differ in transplanted and wet-seededcrops. Significantly more spiders occurred on continuously flooded than intermittentlyflooded plots (Table 1), probably reflecting the higher GLH numbers onthe flooded plots.Microvelia ripple bug and Cyrtorhinus mirid bug declined with crop age onthe main crop but were capable of rapid colonization of newly planted fields (Fig.
204 RICE RATOONING2, 3). Microvelia was highly abundant on the main crop and regained a high level onboth the ratoon and seeded second crops after an initial population buildup.As would be expected of an aquatic species, significantly more Microveliaoccurred on continuously flooded plots.The Cyrtorhinus population was severely reduced by the main crop harvest,probably because their eggs were removed in the straw. Numbers built up slowly onthe seeded second crop, then rapidly declined as the crop matured. Populations werecontinuously low on the ratoon crop, perhaps in response to GLH numbers. Thedifference in Cyrtorhinus numbers between the seeded second crop and the ratooncrop was significant. The higher numbers of GLH on the wet-seeded plots may alsoexplain why Cyrtorhinus was significantly more abundant on wet-seeded plots thanon transplanted plots.Significantly fewer GLH occurred on the ratoon, apparently because of highnumbers of Lycosa hunting spiders. Sasaba and Kawahara (31) underline theimportance of Lycosa in regulating GLH population. They observed that this spiderclimbed rice plants at night. Because GLH usually inhabit the upper canopy, it islikely that Lycosa encountered more GLH than other hopper species.Orb-web spiders spin their webs in the rice canopy where GLH live; they alsocould have selectively preyed on more GLH.On the other hand, high numbers of Atypena space-web spider on the ratooncrop explained the significantly low numbers of WBPH. This small spider couldhave exerted considerable control of WBPH because of its habit of constructingwebs between rice tillers at the base of the rice plants, where WBPH also live.The equal abundance of ripple bugs on both the ratoon crop and the wetseededsecond crops probably explained the lack of difference in BPH numbers onboth ratoon and seeded second crops. Because the ripple bug prefers small hoppernymphs (25), its impact on the pest population should be greatest right after egghatch. This was confirmed in a preliminary cage experiment with BPH in which thepest population was reduced by ripple bug after hatch. Under normal fieldconditions, BPH frequently fall off plants to be attacked by Microvelia.Suitability of ratoon as insect hostResults show ratoon rice as a poor host for RWM, CW, and GSL; survival and bodyweight of these insects were low (Table 3). The GHC, LF, and GLH reared on ratoonrice also showed body weight reductions, indicating that ratoon rice is less nutritiousthan transplanted rice. However, developmental periods of insects tested on ratoonand transplanted rice did not differ significantly.Perhaps leaf toughness of the ratoon plant was responsible for the weightdifferences and lower survival rates of some insect pest species studied. Toughmature leaves and stems make feeding difficult for larvae, nymphs, or maggots,decreasing the rate at which they can ingest leaf material and minimizing anypotential for increased feeding rates that could compensate for the low nutrientcontent of the leaves. Toughness of the leaves or stems of the host plants has beenshown to inhibit feeding by several other species of phytophagous insects (1, 27, 32).These studies suggest that leaf toughness by itself may often function as a defensemechanism against phytophagous insects. It is also possible that toxic secondary
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RICERATOONING1988INTERNATIONAL RICE
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ContentsForewordWelcome 1OverviewRi
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Genetics and varietal improvementIn
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2 RICE RATOONINGthe main crop. Harv
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4 RICE RATOONINGTable 1. Area, prod
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6 RICE RATOONINGTable 2. Rice varie
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8 RICE RATOONING1. Effect of spacin
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10 RICE RATOONINGHowever, no signif
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12 RICE RATOONINGrelating to seed v
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14 RICE RATOONING5. Cultivars that
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Economic perspectivesof rice ratoon
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ECONOMIC PERSPECTIVES OF RICE RATOO
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32 RICE RATOONINGla) Developmental
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34 RICE RATOONINGCutting heightStub
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36 RICE RATOONINGEarly flooding enc
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38 RICE RATOONING2. Factors affecti
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40 RICE RATOONING27. Nair, N.R., an
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42 RICE RATOONING1. Changes in till
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44 RICE RATOONINGTable 2. Character
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46 RICE RATOONING9. International R
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48 RICE RATOONINGplot size is 6 row
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50 RICE RATOONINGimproved ratooning
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52 RICE RATOONINGTable 6. Simple co
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Utilization of rice ratooningby far
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RICE RATOONING IN RIO DE JANEIRO 57
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RICE RATOONING IN RIO DE JANEIRO 59
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Rice ratooningin the Dominican Repu
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RICE RATOONING IN THE DOMINICAN REP
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89111306514772Special points Refere
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72 RICE RATOONINGANDHRA PRADESHBasu
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74 RICE RATOONINGrice observed at t
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76 RICE RATOONINGTAMIL NADUBalasubr
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78 RICE RATOONING19. Reddy, T.G., M
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80 RICE RATOONING1. Rice-growing re
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82 RICE RATOONING2. High cutting he
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84 RICE RATOONINGTable 3. Yield tri
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Rice ratoon crop managementin the h
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RICE RATOON CROP MANAGEMENT IN KARN
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23123722821721922222421423122421722
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98 RICE RATOONING1. The Tungabhadra
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100 RICE RATOONINGthe results of po
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102 RICE RATOONINGTable 4. Effect o
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Ratoon rice researchin Karnataka, I
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RATOON RICE RESEARCH IN KARNATAKA 1
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RATOON RICE RESEARCH IN KARNATAKA 1
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112 RICE RATOONINGTable 1. Area and
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114 RICE RATOONINGonly 7.5-49.7% of
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116 RICE RATOONINGTable 5. Relation
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Scope for rice ratoon croppingin th
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RATOON CROPPING IN NORTHEASTERN IND
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Scope for rice ratoon croppingin th
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RATOON CROPPING IN CENTRAL AND NORT
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RATOON CROPPING IN CENTRAL AND NORT
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Potential of rice ratooningin Madag
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RICE RATOONING IN MADAGASCAR 131a.
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RICE RATOONING IN MADAGASCAR 133Tab
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Potential for rice ratooningin east
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RICE RATOONING IN EASTERN INDIA 137
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Ratooning in Bangladesh:prospects a
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RATOONING IN BANGLADESH 145RATOON C
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RATOONING IN BANGLADESH 147Table 4.
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RATOONING IN BANGLADESH 149OTHER FA
Page 159 and 160: 152 RICE RATOONINGTable 1. Hybrid s
Page 161 and 162: 154 RICE RATOONINGThe studies sugge
Page 163 and 164: 156 RICE RATOONINGVARIETIES AND CUL
Page 165 and 166: 158 RICE RATOONINGspikelet primordi
Page 167 and 168: 160 RICE RATOONINGTable 5. Effect o
Page 170 and 171: Agronomic principles and practiceso
Page 172 and 173: AGRONOMIC PRINCIPLES AND PRACTICES
Page 184 and 185: Rice ratooning: breeding,agronomic
Page 186 and 187: BREEDING, AGRONOMIC PRACTICES, AND
Page 192: BREEDING, AGRONOMIC PRACTICES, AND
Page 195 and 196: 188 RICE RATOONINGwas the most effe
Page 197 and 198: 190 RICE RATOONINGRESULTSMain crop
Page 199 and 200: 192 RICE RATOONINGRatoon tiller reg
Page 201 and 202: 194 RICE RATOONING9. Rister, M. E.,
Page 203 and 204: 196 RICE RATOONINGExcept for rice w
Page 205 and 206: 198 RICE RATOONINGInsect survivorsh
Page 207 and 208: 200 RICE RATOONING1. Stem borer occ
Page 209: 202 RICE RATOONING3. Population dyn
Page 213 and 214: 206 RICE RATOONINGplant chemicals a
Page 215 and 216: 208 RICE RATOONING17. Krishnamurthy
Page 217 and 218: 210 RICE RATOONING1. Yellow dwarf c
Page 219 and 220: 212 RICE RATOONING3. The effect of
Page 221 and 222: 214 RICE RATOONINGAlthough the inte
Page 223 and 224: 216 RICE RATOONINGTable 6. Sheath b
Page 226 and 227: Yellow dwarf disease in ratoon rice
Page 228 and 229: YELLOW DWARF DISEASE IN RATOON RICE
Page 230 and 231: YELLOW DWARF DISEASE IN RATOON RICE
Page 232: YELLOW DWARF DISEASE IN RATOON RICE
Page 235 and 236: 228 RICE RATOONINGTable 1. Estimate
Page 237 and 238: Main crop a Ratoon crop b53.956.155
Page 240 and 241: Disease and insect pestsand their c
Page 242 and 243: DISEASE AND INSECT PESTS IN RICE RA
Page 244 and 245: DISEASE AND INSECT PESTS IN RICE RA
Page 246 and 247: Inheritance of ratooning abilityin
Page 248 and 249: INHERITANCE OF RATOONING ABILITY IN
Page 250 and 251: INHERITANCE OF RATOONING ABILITY IN
Page 252: INHERITANCE OF RATOONING ABILITY IN
Page 255 and 256: 248 RICE RATOONINGShould the season
Page 257 and 258: 250 RICE RATOONINGYield and yield-c
Page 259 and 260: 252 RICE RATOONINGMain-crop photosy
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254 RICE RATOONINGShort-termGiven t
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Commercial ratoon rice productionin
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COMMERCIAL RATOON RICE PRODUCTION I
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0.180.200.490.250.160.270.390.350.3
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268 RICE RATOONING1. Path analysis
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270 RICE RATOONINGRecommendationsVa
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ParticipantsT. AhmedRice Experiment
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Varietal indexA200, 221Achra 108/1,
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VARIETAL INDEX 277IR2061-465-1, 12I
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VARIETAL INDEX 279RU7502006, 49, 51
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