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EARLY GENERATION YIELD PERFORMANCE OF DIFFERENT FIELD PEA PLANT TYPES

S. M. Liu and L. O. Brien

Plant Breeding Institute, University of Sydney, Narrabri, NSW 2390

Abstract

The effect of genes for plant leaf type and height on grain yield in the northern region were examined using F3 breeding lines of the cross of Trapper, a conventional leafed, tall pea, with the semileafless, semidwarf advanced breeding line M257-5-1. This cross produced four plant phenotypes, conventional/tall, conventional/semidwarf, semileafless/tall and semileafless/semidwarf. Grain yield and lodged plant height at harvest maturity of lines of each phenotype were compared using data from replicated hand-harvested microplots.

The highest yielding lines were conventional leafed peas, irrespective of the plant height genes involved. Lines equal in yield to the best control variety were only found among conventional leafed phenotypes. The semileafless plant habit improved plant standing ability at maturity.

When a minimum lodged plant height at harvest ripeness was imposed as an essential requirement for ease and speed of harvest and acceptance of the crop by northern growers, semileafless phenotypes provided the most lines with yield better than the best parent and approaching the yield of the best control variety. Consequently, the semileafless phenotype appears best suited to the harvest demands of the northern region, even though they may not be the outright highest yielding lines.

In recent decades considerable effort has been expended to restructure plant type in legume crops to increase yield potential and for ease and speed of harvesting. In the northern cropping region, the dominant summer rainfall pattern dictates that only erect plant types will be acceptable agronomically.

In field pea, semileafless and semidwarf plant habits have been developed in place of conventional leafed, tall plant types. The effects of these changes have been widely evaluated in pea variety trials (1, 2, 3, 4), but the results have not provided a clear-cut answer about which plant type is superior.

A comparison of the performance of F2-derived lines differing for plant leaf type and height in the F3 generation was undertaken at Narrabri, northern NSW in an attempt to define the preferred plant type to optimise harvestable grain yield in the region.

Materials and methods

F2 lines derived from a cross of the conventional (Cl), tall (Tl), powdery mildew tolerant variety Trapper and the semileafless (Sl), semidwarf (Sd), powdery mildew resistant advanced breeding line M257-5-1 were grown in a two replicate α -lattice design experiment along with their parents and three control varieties, Dinkum (Sl/Sd), LE 25 (Cl/Sd) and PSI 10 (Sl/Tl) in 1997 at the Plant Breeding Institute, Narrabri. The cross segregated to produce four plant phenotypes and 20-30 lines from each type were evaluated. To remove the confounding effects of powdery mildew on yield performance only fully resistant lines are considered.

Plots were hand-planted microplots consisting of 16 sound seeds planted in two rows (8 seeds/row) with 20 cm between rows and 10 cm between plants within rows. A 1 m gap separated the plots. Lodged plant height was measured on each plot at maturity and all plots were hand-harvested at ground level and grain yield recorded.

Results

The means for grain yield of the different morphological types indicated that the highest yielding lines were obtained from conventional leafed peas irrespective of the plant height genes involved. The semileafless/semidwarf type had the lowest mean. Ranges indicated that lines with yield superior to the best parent, Trapper (354.5 g/plot), existed for all four plant types. Lines equal in yield to the best control variety, LE 25 (448.5 g/plot) were only found among the conventional leafed types (Table 1).

The mean lodged plant height data indicated that the semileafless plant habit appeared to improve plant standing ability at maturity. The ranked order for mean lodged plant height was the direct reverse of that for grain yield. Means and ranges for lodged plant height showed that the tallest plants were of the semileafless/semidwarf phenotype (Table 1).

As plant lodging can severely slow harvesting speed and increase harvesting loss, a minimum lodged plant height is essential for commercial production of field pea in the northern region. Selection was practised within each plant type by selecting for plants with a minimum lodged plant height of more than 27 cm. This showed that selection did not change the rank order for mean grain yield of each plant type (Table 2), but significantly, the greatest number of lines with lodged plant height greater than 27 cm were semileafless plant types.

Table 1: Parent, control and F3 generation means and ranges for grain yield and lodged plant height for the four plant types

Trait

Plant type

Parents

Controls

ClTl

ClSd

SlTl

SlSd

No. lines

12

11

10

8

Grain yield (g/plot)

Mean

392.1

441.6

364.1

347.9

334.0

322.6

Range Mix.

317.2

398.4

308.0

223.6

313.4

246.7

Max.

480.8

483.1

416.0

402.4

354.5

448.5

LSD 0.05

113.8

Lodged plant height (cm)

Mean

26.2

21.6

31.0

34.9

31.1

26.0

Range Min.

22.5

17.8

25.3

27.5

27.9

23.5

Max.

35.5

27.3

36.8

42.5

34.3

28.5

LSD 0.05

9.6

Table 2: Number of retained lines and means and ranges of grain yield for each plant type after selection for minimum lodged plant height

 

ClTl

ClSd

SlTl

SlSd

No. retained lines

3

1

7

8

Grain yield (g/plot)

Mean

401.7

463.8

374.5

347.9

Range

359.8-433.1

463.8

308.0-416.0

223.6-402.4

Discussion

Grain yield in hand harvested microplots in the absence of selection pressure for minimum lodged plant height indicated that conventional leafed peas had the highest mean yield and were the highest yielding lines. However, when the demand for a minimum lodged plant height for ease and speed of harvesting were imposed, an essential requirement for acceptance of pea production by growers in the northern region (3), then the greatest number of lines of acceptable lodged plant height were semileafless plant types. While the highest yield of the best semileafless lines in this cross did not match those of conventional types in this hand harvested comparison, they could be expected to be superior in a commercial situation because their increased lodged plant height would confer advantages in terms of ease and speed of harvesting and perhaps less harvest loss through reduction of lodging.

References

1. Armstrong E. L. and Pate J. S. 1994. Aust. J. Agric. Res. 45: 1363-1378.

2. Card T., Frusciante L. and Monti L. M. 1987. Crop Sci. 27: 852-856.

3. Moore S. G., Wheatley D. M., O'Brien L. and Jessop R. S. 1996. Proc. 8th Aust. Agron. Conf. Toowoomba. PP 438-441.

4. Wehner T. C. and Gritton E. T. 1981. J. Amer. Soc. Hort. Sci. 106: 272-278.

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