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extensively tested by farmers in the HBT and is a low-cost, low-risk technology thathas been adopted widely as a recommended practice (Saha 2002) on its own meritsbut also as a means to address other constraints (see below).Integrated pest managementThe biotic stresses that affect chickpea in the HBT include collar rot (caused bySclerotium rolfsii), Fusarium wilt, Botrytis gray mold (BGM, caused by Botrytiscinerea), and pod borer (Helicoverpa armigera). The extent of genetic resistanceto these pests and diseases in chickpea genotypes is discussed by Johansen et al(this volume), but simple agronomic interventions can help to reduce losses. Forinstance, seed priming was shown to reduce the incidence of collar rot (Musa et al2001) and appropriate plant spacing facilitates good canopy ventilation that reducesthe development of BGM (Bakr et al 2002). Pod borer, however, is the major bioticsource of yield loss in chickpea. PROVA estimates yield losses of 10–50% caused bythis pest each year in the HBT and pod damage is particularly apparent to farmers,who repeatedly list it as an important constraint to chickpea production (see, forexample, Saha 2002). In 2001-02, preliminary trials by PROVA showed the efficacyof spraying Helicoverpa nuclear polyhedrosis virus (HNPV) in controlling pod boreron chickpea (Musa and Johansen 2003b). This virus is specifically lethal only forHelicoverpa armigera and is thus an environmentally safe means of managing thepest, in contrast with the use of chemical insecticides with all of their adverse sideeffects (Grzywacz et al 2004). It was therefore decided to develop an HNPV-basedintegrated pest management (IPM) system suitable for chickpea in the HBT. Simpleinterventions were tested, separately and in combination, in a series of field trialsbetween 2002 and 2005.In the 2002-03 season, three separate subexperiments were conducted on the effectsof (A) bird perches, (B) HNPV spraying, and (C) mixed cropping. Five replicationseach of the following treatments were superimposed on existing chickpea cropsand mixed crops in the first week of February 2003:A. Bird perchesSixteen T-shaped perches were placed at 5-m intervals (i.e., 4 4 = 16) withina 25 25-m area of existing chickpea. A similar uniform area of 25 25m without bird perches was identified within 10–20 m of the first plot.B. HNPV sprayingChickpea in selected areas of 25 25 m was sprayed with either HNPV(250 larval equivalents ha –1 ) or with a chemical insecticide (Ripcord, using 1mL active ingredient L –1 water) when small larvae (
In each of the plots, numbers of Helicoverpa armigera larvae on chickpea werecounted in 5 1-m 2 quadrats per plot at three times. Counts were made at 3–4 daysafter spraying of HNPV and Ripcord. Spraying times were 4 and 22 February and22 March 2003. Plant numbers of all crop species per 5 1-m 2 quadrat were alsomeasured on 22 March. Chickpea suffered severe damage by BGM in this season socounting of damaged pods and estimation of grain yield were not done.In the 2003-04 season, subexperiments and treatments were the same as in theprevious season but with an additional subexperiment comparing a combined IPMtreatment (bird perches + HNPV + mixed cropping) with a nonprotected control. Therewere five replications and in this season the plots were purpose-sown (rather thansuperimposed on existing plots as in the previous year). At maturity, plant number,the percentage of damaged pods, and grain yield of chickpea were recorded in 10randomly located 1-m 2 quadrats.In the 2004-05 season, combined IPM treatments were tested against nonprotectedcontrol treatments in both sole crop and mixed crop (with linseed only) situations.The control for the mixed crop was a sole chickpea crop without HNPV spraying orplacement of bird perches. Ten paired comparisons were placed in adjacent 25 25m plots in farmers’ fields in Godagari and Nawabganj Sadar upazillas.Results of IPM trialsIn the 2002-03 season, the presence of bird perches significantly reduced larval numbersat the second and third samplings (Table 1). We believe that this is probably the firstrecorded quantification of this effect on chickpea. Plant population was not significantlydifferent between the treatment plots, ranging from 22 to 37 plants m –2 . Observationby farmers indicated that the perches did indeed attract birds, which ate the larvae. Asnoted above, it was not possible to estimate any treatment-related differences in yieldor yield components because of the severe damage to the crop by BGM.Application of HNPV was at least as effective as the best locally available chemicalinsecticide, Ripcord, in minimizing larval numbers (Table 1). Larval numbers weresignificantly higher without application of either of these sprays. Plant populationswere similar between treatments, in the range of 18–33 plants m –2 .There were significantly fewer larvae on chickpea in mixed crops with barley orlinseed as compared with sole crops (Table 1). Mixed crops can have lower densitiesof chickpea plants relative to sole crops but that was not the case in these trials. Meanchickpea density in the sole crop was 27.6 plants m –2 and not significantly differentfrom the 28.6 plants m –2 in the mixed crop. This result confirms in farmers’ fields thatmixed cropping discourages Helicoverpa pod borer damage to chickpea, consistentwith the previously reported results found in small-plot on-station trials.The positive effects of the use of bird perches, HNPV application, and mixedcropping in numbers of Helicoverpa pod borer larvae on chickpea were confirmed inoperational-scale plots in farmers’ fields. They thus remain worthy components of anIPM package for chickpea. However, treatment-related effects on yield could not bemeasured due to overriding damage to the crop caused by BGM.122 Harris et al
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Improving AgriculturalProductivity
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Bangladeshi experiences with a drum
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AcknowledgmentsIRRI is most gratefu
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The High Barind Tract: a challengin
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irrigation across the entire Barind
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Workshop synthesis
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and, with representatives from the
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Subsistence pressureLand pressure,
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HerbicidesEarlier efforts to introd
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volume). PVS is an effective way to
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Farmers may use wet-seeded DSR as a
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process and distributing HNPV to fa
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an NGO, have successfully collabora
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Workshop discussionParticipants dis
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How can we identify a short-duratio
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to fixed tenancy. The implication i
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Opportunities for improving ricepro
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that the reliability and productivi
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Table 1. Planting dates, direct-see
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Table 2. (A) Mean effect of fertili
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Table 5. On-farm trials of a drum s
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Upper toposequenceYield (t ha -1 )7
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and perennial grasses (e.g., Ischae
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Direct-seeded rice in the HighBarin
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Table 1. Sample selection for costs
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Table 4. Variations in weed managem
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Table 7. Labor requirements (days h
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Table 10. Farmer perceptions of dis
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Farmers (no.)1412108DSRWet-seededDr
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able commercially. Other OFT farmer
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Box 1. Farmers’ comments on DSRPo
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NotesAuthors’ addresses: M.A. Jab
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This paper explores the role of som
Page 80 and 81: (Olsen method, atomic absorption),
Page 82 and 83: Mean biomass (g m −2 )1,000.000Fi
Page 84 and 85: Fig. 3. Log rank abundance of weed
Page 86 and 87: attested by Fig. 2). Diversity in t
Page 88 and 89: Bangladeshi experiences with a drum
Page 90 and 91: Table 1. Grain yield and crop durat
Page 92 and 93: Table 5. Grain yield and growth dur
Page 94 and 95: ACEy = 0.0001x + 0.7089Yield (t ha
Page 96 and 97: Table 11. Partial budget analysis f
Page 98: ConclusionsDirect wet-seeded rice u
Page 101 and 102: A 178% increase in rice production
Page 103 and 104: Table 1. Components of yield gaps d
Page 105 and 106: Table 3. Weed management in Comilla
Page 107 and 108: Table 5. Weed management practices
Page 109 and 110: Table 7. Significance (P H o ) of t
Page 111 and 112: Since 2000, there has been an incre
Page 114 and 115: Identifying varieties for the High
Page 116 and 117: Table 1. Rice varieties bred by cli
Page 118 and 119: Table 2. Grain yield advantage of J
Page 120 and 121: Table 3. Plant height and crop dura
Page 122 and 123: Table 6. Summary of adoption and sp
Page 124 and 125: Freeman GH, Perkins J.M. 1971. Envi
Page 126: Opportunities for improving rabi cr
Page 129: Grain yield (t ha -1 )2.0npp1.5LSD
Page 133 and 134: Table 2. Effect of IPM components o
Page 135 and 136: Unit plot size was 10 10 m and the
Page 137 and 138: Yield (t ha -1 )5Straw4321GrainP (g
Page 139 and 140: Nodulation score3AControl Soil Mo P
Page 141 and 142: even at low levels of production. B
Page 144 and 145: Integration of chickpea and other r
Page 146 and 147: Grain yield (t ha -1 )3.02.51989-99
Page 148 and 149: Improved Improved Rainfed rainfed C
Page 150 and 151: Table 1. Preharvest and postharvest
Page 152 and 153: Greater resistance to Helicoverpa p
Page 154 and 155: wheat varieties). There is also sco
Page 156 and 157: Developing seed systems fordissemin
Page 158 and 159: This paper describes attempts to em
Page 160 and 161: seed needed to attain the recommend
Page 162 and 163: introduced to permit sale beyond th
Page 164: pesticides, inoculation with benefi
Page 168 and 169: for the rabi crop in 2001. Hence, b
Page 170: where farmers decided not to relay-
Page 174 and 175: Table 2. Mean dates of T. aman harv
Page 176 and 177: Table 4. Subsistence pressure and r
Page 178 and 179: Table 7. Subsistence pressure and r
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cite the absence of rent as a facto
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abi cropping in the HBT through ear
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Formulation and dissemination ofimp
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in India, for which shorter-duratio
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Applied researchOFTsAdaptive resear
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Table 1. Recommended package of pra
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Table 2. Grain yields (kg ha -1 ) o
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Table 4. Grain yields (t ha -1 ) of
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Table 6. Mean grain yields (t ha -1
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constraints present. This in itself
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Extending rabi cropping in rice fal
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Table 1. Estimates of rice area dur
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Yield (kg ha -1 )1,2001,00080060040
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Future disseminationThrough dialogu
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Direct seeding of rice andopportuni
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Table 1. Time of establishment and
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Table 3. Weed density and biomass a
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than in Central Java and many farme
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Proportion abundance (log scale)Ran
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CAN FIELD BE DRAINED?YesCAN FIELD B
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Johnson DE, Mortimer AM. 2005. Issu
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Zhao DL, Atlin GN, Bastiaans L, Spi
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