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«D. ANITHA KUMARI THESIS SUBMITTED TO THE ACHARYA N.G RANGA AGRICULTURAL UNIVERSITY COLLEGE OF AGRICULTURE, RAJENDRANAGAR IN PARTIAI FULFILLMENT OF ...»

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flowers of 4 genotypes (the 12 genotypes were divided into three sets and tested along with the susceptible check lCPL 87). Flowers Rom four genotypes were kept in a petri dish arena (9 cm) along with the check (ICPL 87). Ten 3" instar larvae were released in each petri dish arena. The extent of larval feeding was rated using visually on a 1-9 damage rating scale aRer 24 and 48 h. The experiment was repeated five times. In the latter stage, the test genotypes were divided into shortduration genotypes and long- duration types. Eight pods from the short-duration varieties were arranged in a petri dish arena, and the experiment was replicated five times. Ten third-instar larvae were released in each petri dish, and the larval feeding was assessed visually on a 1-9 rating scale after 24 and 48 hr.

3.2.7.4 Effect of extracting the pod surface chemicals by different solvents on feeding preference by the H.armigera larvae

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hexane, methanol or double distilled water and stirred for 120 seconds with a glass rod. The extracted pods were left to air dry for 2 hrs to allow any remaining solvent to evaporate. The 3rd instar larvae were exposed to (a) control pod, and a pod extracted in hexane, @) control pod and a pod extracted in methanol, (c) control pod and a pod extracted in distilled water.

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single pod. Singe pod may be 1) without treatment (which acts as a check), 2) extracted in hexane, 3) extracted in methane, 4) extracted in distilled water (Plate 7).

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genotypes. The damage ratings were observed after 24 hrs and 48 hrs.

Dual-choice conditions 3.2.7.4.3 The effects of pod surface chemistry on the food selection behaviour of larvae were investigated by presenting the larvae with choices between pods that had been surface extracted in either hmane, methanol or water and un extracted pods for all the twelve genotypes (Plate 8).

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studied by comparing the chemically protected (sprayed) and unprotected crop (unsprayed) plots. The plot size was 45 sqm for each treatment. The crop in the protected plots was sprayed five times during flowering and pod formation stages with different insecticides. Five sprays of 3 insecticides (methomyl, cypermethrin and monocrotophos) with a knapsack sprayer were applied to each plot at 10 to 15 days interval starting at flower initiation. Observations on yield and population of H. armigera larvae were made for each treatment (Plates 9 and 10). Counts of the larvae were first made visually at initiation of flowering, and were continued at weekly intervals until harvest on the tagged inflorescences. The number of damaged and total pods were counted on three plants at random from the protected and unprotected plots at harvest. The two treatments in respect of various parameters of grain yield were compared by using the split plot technique. The mean weight of total expected grains was calculated on the basis of 100 healthy pods in the protected and unprotected plots. Avoidable loss due to H. armigera damage was calculated (Taneja and Nawanze, 1989). The assessment of loss in yield of 12 pigeonpea genotypes by the grain pod borer, H, armigera was done using the following formulae.

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Studies on the mechanisms of resistance to Helicoverpa armigera (Hubner) in pigeonpea [Cajanus cajan (L.) Millsp.] were conducted at the International Crops Research Institute for Semi Arid Tropics, Patancheru between June 2000 to December 2002. The results of these experiments are elucidated below.

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significant differences among the genotypes in visual damage rating (DR), 100-seed weight, per cent pod damage, and days to 50% flowering. The differences were not significant among the genotypes tested for days to maturity, seeds per pod, number of eggs and larvae at 5*, 7', 9*, 20" and 30* days after flowering, and grain yield.

During the 2001 rainy season there were significant differences in 100-seed weight, days to 50% flowering, and grain yield. There were no significant differences among genotypes for damage rating, pod damage per cent, seeds per pod, days to

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significant differences in days to 50% flowering, visual damage rating, grain yield per plot, 100-seed weight and also for number of eggs and total larvae. There were no significant differences among the genotypes for pod damage per cent, days to maturity and seeds per pod. In the second planting, there were significant differences in pod damage, damage rating, 100-seed weight, grain yield, and total eggs and larvae. There were no significant differences among genotypes for days to 50% flowering, days to maturity, seeds per pod. Thus there was strong genotype'environment interaction for different parameters recorded.

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During the 2000 rainy season, among the short-duration genotypes, lowest number of eggs were recorded in ICPL 187-1(4.27), while lowest number of larvae were recorded on ICPL 98001 (4.04) (Table 4 and Fig. I). In case of longduration genotypes lowest number of eggs were recorded in ICPL 871 19 (4.28) while lowest number of larvae were recorded on ICPL 332 (4.21). In second planting (Table 5 and Fig.2) lowest number of eggs were recorded on ICPL 871 19 (4.22) and lowest number of larvae on ICPL 332 (3.33) followed by ICP 7035 (3.67) among long duration genotypes. In case of short duration genotypes lowest number of eggs were recorded on T 21 (4.13) and lowest number of larvae on ICPL 88039 (4.80).





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total number of eggs and larvae among the genotypes tested. Lowest number of eggs were recorded on ICPL 98008 (2.47), and T21 (3.09) while lowest number of larvae were recorded on ICPL 98001 (1.90), followed by ICPL 98008 (2.84) and T 21 (2.94) (Table 6 and Fig.3). Amongst the long-duration genotypes lowest number of eggs were recorded on ICP 7035 (2.74). In the second planting (Table 7) lowest number of eggs were recorded on lCPL 98008 (2.16) and ICPL 7203-1 (2.34).

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Pod damage Rating (1=10%pods damaged and 9=80?4 pods daroaged).

ICPL 98008 (2 55) In case of short durat~ongenotypes In the second plantlng lowest number of eggs were recorded on ICPL 7035 (3 03) Lowest number of larvae were recorded on ICPL 871 19 (3 28) (Table 7 and Fig 4) 4.1.2 Days to 50% flowering and days to maturity

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recorded m ICPL 88039 (2 33), ICPL 98008 (3 67), and ICP 7203-1 (4 67) among the short-duratlon genotypes In the first plantlng (Table 4) In the second plant~ng,

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2001 ralny season lowest pod damage ratlng was recorded on T 21 (4 0) and ICPL 187-1 (4 0) m the first plantlng (Table 6) In case of long-durat~ongenotypes lowest pod damage ratlng was recorded a ICPL 84060 (2 67), ICPL 871 19 (3 OO), and ICP 7035 (4 33) (Table 4) In the second plant~ng, lowest pod damage ratlng was recorded In ICPL 332 (3 33) followed by ICP 7035 (3 67), ICPL 84060 (5 00) (Table 5) Dur~ng 2001 rruny season lowest pod damage ratlng was recorded on the

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During the 2000 rainy season first planting among the short-duration genotypes lowest pod damage was recorded in ICPL 187-1 (21.75%). followed by ICPL 87091 (22.68%) and ICPL 98001 (24.32%), ICPL 332 (31.09%) and ICP 7203-1 (34.45%) as compared to 46.02% damage in ICPL 87 in the first planting (Table 4). In case of long-duration genotypes lowest pod damage was recorded in ICPL 332 (3 1.09%). Pod damage per cent was more in second planting compared to 2000 rainy season first planting. Among the short duration genotypes lowest pod damage was recorded in ICPL 88039 (47.66) and higher in case of ICPL 98008 (83.85%). In case of long duration genotypes lowest pod damage per cent was recorded in ICP 7035 (68.87) (Table 5). During the 2001 rainy season first planting lower pod damage was recorded in ICP 187-1 (43.75%) followed by ICPL 88039 (46.75%) and ICP 7203-1 (52.02%) as compared to ICPL 87 (82.51%) among the short duration genotypes. In case of long duration genotypes lowest pod damage was recorded in ICPL 84060 (56.72) (Table 6). In the second planting, pod damage was lower in ICPL 187-1 (44.98%) followed by ICPL 88039 (48.57%).

ICPL 7203-1 (56.32%) as compared to 83.5% damage in ICPL 87 among short duration genotypes. In case of long duration genotypes lower pod damage per cent was recorded in ICPL 84060 (55.11) (Table 7).

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recorded in lCPL 87119 (1 1.44 g) followed by ICP 7035 (1 1.43 g) among long duration genotypes (Table 8). In case of short duration genotypes highest 100 seed weight was recorded in ICP 7203-1 (9.85 g) followed by ICPL 87091 (9.69 g).

During the second planting highest 100 seed weight was recorded in ICPL 871 19 (10.70 g) followed by ICP 7035 (10.10 g) in case of long duration genotypes (Table 9). In case of short duration genotypes highest 100 seed weight was recorded in 1CP 7203-1 (8.93 g) followed by ICPL 87091 (9.01 g). The 100 seed weight of the genotypes were higher during first planting compared to second planting.

During 2001-2002 first planting highest 100 seed weight was recorded in ICP 7035 (1 1.40 g) followed by ICPL 871 19 (1 1.OO g) among long duration genotypes (Table 10). In case of short duration genotypes highest 100 seed weight was recorded in ICPL 87091 (9.10 g). During second planting highest 100 seed weight was recorded in ICP 7035 (10.20 g) among long duration genotypes (Table 1I). In case of short duration genotypes highest 100 seed weight was recorded in ICP 7203-1 (8.69 g).

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ICPL 98008 had 4.00 to 4.50 seeds per pod. The other genotypes had 3 00 to 3.50 seeds per pod. During 2000-2001 first planting highest seeds per pod were recorded in ICPL 871 19 (5.00) followed by lCPL 84060 (4.20) among long duration genotypes. Among short duration genotypes highest seeds per pod were recorded in ICPL 98008 (4.60) followed by ICPL 98001 (3.80) (Table 8). During second planting highest seeds per pod were recorded in ICPL 98008 (4.60) among short duration genotypes. Among long duration genotypes highest seeds per pod were recorded in lCPL 871 19 (5.00) (Table 9). During 2000-2001 first planting and second planting the same trend was repeated.

Table 8: Agronomic performance of 12 plgeonpea genotype8 in rainy searon, flm planting (2000-2001)

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R-Resistant check, S-Susceptible check.

Table 10: Agronomlc performmce of 12 pigeonpea genotypes in rainy reason, first planting (2001-2002)

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in ICPL 332 (173.00 g) followed by ICPL 871 19 (151.00 g) among long-duration genotypes and in ICP 7203-1 (148.00 g), and ICPL 98008 (147.00 g) in the first planting among the short-duration genotypes (Table 8). In the second planting grain yield per three plants was greater in ICPL 332 (167.40 g), ICPL 871 19 (145.00 g) and ICPL 84060 (130.70 g) in case of long-duration genotypes and in ICPL 98001 (141.50 g) in case of short-duration genotypes as compared to 51.80 g in ICPL 87 (Table 9). During the 2001 rainy season highest grain yield was recorded in ICPL 871 19 (147.00 g) followed by ICPL 332 (136.00 g) among long-duration genotypes and in ICPL 98001 (144.60 g), ICP 7203-1 (143.30 g) in the first planting (Table 10). During the second planting higher grain yield per three plants was recorded in ICPL 332 (163.80 g) in case of long duration genotypes and lCPL 98001 (141.50 g) in case of short duration genotypes.

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ICPL 84060 (5667 kg ha"), ICPL 871 19 (5394 kg ha") in case of long-duration genotypes and lCPL 187-1 (3767 kg ha"), T 21 (3017 kg ha.') and ICP 7203-1 (381 1 kg ha") in case of short-duration genotypes during the 2000 rainy season in the first planting (Table 8). During the second planting highest grain yield was recorded in ICPL 332 (4361 kg ha") followed by ICPL 84060 (3126 kg ha") among

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was recorded in ICP 7203-1 (4361 kg ha-') (Table 9). During the 2001 rainy season grain yields were higher in ICPL 332 (3978 kg ha"), lCPL 84060 (3071kg ha"), ICPL 871 19 (285 1 kg ha") among long-duration genotypes and ICPL 187-1 (2992 kg ha"), ICP 7203-1 (2514 kg ha"), T 21 (2292 kg ha") as compared to ICPL 87 in case of short-duration genotypes (Table 10). During the second planting highest grain yield was obtained in ICPL 332 (3501 kg ha") followed by ICP 7035 (3501 kg ha") in case of long duration genotypes. In case of short duration genotype highest grain yield was obtained in ICPL 187-1 (2371 kg ha") (Table 11).

Genotypic stability for resistance to H.armigera 4.1.6 Stability statistics for yield components and pod borer resistance are presented in Tables 12, 13, 14, 15 and 16 for the 12 pigeonpea genotypes.

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100 seed weight varied from 7.00 g (ICPL 332) to 11.00 g (ICPL 871 19 and ICP 7035). Among the twelve pigeonpea genotypes tested over four seasons 'b' values were significantly greater than 1 for ICP 7203-1, ICPL 87091, T 21, ICPL 87 among short duration genotypes and in ICPL 84060, ICPL 871 19, ICP 7035 among long duration genotypes (Table 12).

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environment (G x E) interaction among the 12 pigeonpea genotypes. Among the long duration genotypes highest grain yield per plot was recorded in ICPL 332 (2.40 kg plot.') but with slope 0.57 and residual mean squares SiZ value equal to 1 indicating its unstability followed by ICPL 332. Highest grain yield per plot was Table 12: Estimates of stability for 100 seed weight in 12 pigeonpea genotypes tested over four seasona (2000-2002)

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R - Resistant, S - Susceptible, bi = slope of regression line, SEbi - Standard error of bi, 6i2 Residual mean squares.

recorded in ICPL 84060 (1.91 kg plot"), but slope (0.58) and residual mean squares equal to 0 indicating its unstability. Among the short duration genotypes highest grain yield was recorded in ICPL 98001 followed by ICPL 187-1. In case of ICPL 98001 'b' value is greater than one and zero residual mean square value indicates its slight stability over the four seasons (Table 13).

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