Soybean Performance Following Severe Hail

Erik B.G. Feibert, Clinton C. Shock, and Lamont D. Saunders
Malheur Experiment Station
Oregon State University
Ontario, OR, 1998

Introduction

Soybean is a potentially valuable new crop for Oregon. Soybean could provide a high quality protein for animal nutrition and oil for human consumption, both of which are in short supply in the Pacific Northwest. In addition, edible or vegetable soybean production could be exported to the Orient and provide a raw material for specialized food products. Soybean is valuable as a rotation crop because of the soil-improving qualities of its residues and its N2 -fixing capability. Because of the high-value irrigated crops typically grown in the Snake River valley, soybeans may be economically feasible only at high yields.

Soybean varieties developed for the midwestern and southern states are not necessarily well adapted to Oregon's lower night temperatures, lower relative humidity, and other climatic differences. Previous research at Ontario has shown that, compared to the commercial cultivars bred for the midwest, plants for eastern Oregon need to have high tolerance to seed shatter and lodging, reduced plant height, increased seed set, and higher harvest index (ratio of seed to the whole plant). There is also a need to identify semi-dwarf cultivars that will grow and yield well under high seeding rates and narrow row spacing. Yields could also be increased by increasing the seeding rate from 200,000 seeds/acre to 300,000 seeds/acre if semi-dwarf lines were found adapted to local conditions.

Majid and Jolliff at OSU Corvallis identified a soybean line that would fill pods when subjected to cool night temperatures. Those lines were crossed at Corvallis with productive lines to produce OR 6 and OR 8, among others. At this point, the development moved to Ontario, OR. We had OR 6 and OR 8 crossed with early-maturing high-yielding semi-dwarf lines by Cooper to produce semi-dwarf lines with potential adaptation to the Pacific Northwest. Selection criteria at the Malheur Experiment Station included high yield, zero lodging, zero shatter, low plant height, and maturity in the available growing season. In 1992, 241 single plants were selected from five F5 lines that were originally bred and selected for adaptation to eastern Oregon. Seed from these selections was planted and evaluated in 1993. A total of 18 selections were found promising and selected for further testing in larger plots in 1994 and 1995. Starting in 1995 all lines were planted at 300,000 seeds/acre. This report summarizes work done in 1998 as part of the continuing breeding and selection program to adapt soybeans to eastern Oregon, and compares 1998 yields after hail with the performance during the period 1994 -1997.

Procedures

The 1998 line evaluation trial was conducted on a Owyhee silt loam previously planted to wheat. The herbicide Dual at 1 lb ai/acre was broadcast preplant and incorporated with a bed harrow on May 9.

The seed of each variety was cleaned of broken seed pieces and the percentage of seeds with cracked seed coats was estimated. The seeding rate for each variety was increased to account for the seeds with cracked seed coats. The seed had Apron fungicide applied. Seed was planted on May 20 at 300,000 seeds/acre in rows 22 inches apart. Rhizobium japonicum soil-implant inoculant was applied in the seed furrow at planting. Emergence began on May 31. The crop was furrow irrigated as necessary.

Eleven of the single plant selections from 1992, five cultivars, and OR 6 and OR 8 were planted in replicated plots four rows wide by 25 feet long in 1998. The experimental design was a randomized complete block with five replicates. All plots were cut to 23 feet.

Plant height and reproductive stage were measured weekly for each cultivar. Prior to harvest, the cultivars were evaluated for lodging and seed shatter. The middle two rows in each four-row plot were harvested on October 14 using a Wintersteiger Nurserymaster small plot combine. Beans were cleaned, weighed, and oven dried to determine moisture content. Dry bean yields were corrected to 13 percent moisture. Data were analyzed by analysis of variance. Means separation was determined by the protected least significant difference test.

Results and Discussion

Growing conditions in 1998 were unfavorable for crop growth and productivity. The season started with cool and wet weather. The month of May had 4.55 in of rainfall compared to the historic mean for the Malheur Experiment Station of 1.02 in. May had 29 percent fewer and June had 18 percent fewer growing degree days (50 -86 0F) than the previous 10 year mean. A severe hail storm on July 4 resulted in heavy damage to the plants including 80 percent leaf loss and substantial stem breakage. The plants regrew but did not reach full stature. Yields for 1998 ranged from 14 to 47 bu/acre (Table 1). On average, yields in 1998 were 39 percent lower than the previous 4 year average (Table 2). The cultivars and OR selections lodged heavily, and some took too long to mature or did not reach adequate harvest maturity for efficient combining. Most of the 1992 single plant selections reached physiological maturity in 128 days or less, had no lodging, and had seed sizes large enough for the manufacturing of tofu (< 2,270 seeds/lb).

Yields of all lines dropped starting in 1995 when the planting rate was increased from 200,000 to 300,000 seeds/acre (Table 2). The drop in yield may be due to the increase in seeding rate. On average, the Ontario lines have out yielded the commercial cultivars. Several lines combine early maturity, comparatively high yields, no shatter and no lodging (Table 3). The lines M92-225 and M92-237 have light hilum color.

Table 1. Performance of soybean cultivars after severe hail on July 4. Malheur Experiment Station, Oregon State University, Ontario, OR, 1998.

Cultivar

Days to maturityz Days to harvest maturityy

Lodging

Shatter

Height

Yield

Seed count
days from emergence 0-10x percent cm bu/acre seeds/lb
M92-223 132 n 3 0 55 20.9 1930
M92-350 115 n 0 0 64 34.9 2168
M92-330 115 128 0 0 46 41.8 2195
M92-237 115 128 0 0 49 31.9 2049
M92-220 121 128 0 0 60 47.4 1974
M92-217 137 n 0 0 55 25.3 2000
M92-225 115 n 0 0 42 27.8 2195
M92-314 137 n 0 0 56 28.6 1962
M92-085 115 n 0 0 56 29.4 2030
M92-213 128 n 0 0 70 26.9 2084
M92-239 128 n 0 0 46 23.5 2227
Agassiz 132 n 6 0 62 21.7 1984
OR-8 137 n 7 0 74 13.6 2055
Gnome 85 132 n 9 0 72 23.9 2040
Lambert 132 n 9 0 71 35.2 1934
OR-6 115 n 8 0 60 33.1 1985
Sibley 137 n 9 0 42 14.8 1828
Evans 137 n 10 0 69 25 1972
LSD (0.05)           7.6 116
z Pods yellowing, 50 percent of leaves yellow.

y Stems dry enough to be combined, 95 percent of pods brown.

x 0 = none, 10 = 100 percent lodging.

n = harvest maturity was only reached after light frosts in early October.

Table 2. Yield of soybean cultivars in five years ranked by 1994-1997 average yield. Hail depressed yields in 1998. Malheur Experiment Station, Oregon State University, Ontario, OR, 1998.

Cultivar

Yield

1994

1995

1996

1997

1998 with hail Average 1994-1997 Average 1994-1998
---------------------------------- bu/acre ----------------------------------

M92-314

63.2 48.9 57.8 49.2 28.6 54.8 49.5

M92-220

62.0 49.6 46.3 54.6 47.4 53.1 52.0

M92-350

63.6 55.2 43.0 49.9 34.9 52.9 49.3

M92-330

57.8 51.1 55.0 44.8 41.8 52.2 50.1

M92-225

62.8 49.1 51.7 43.7 27.8 51.8 47.0

M92-213

61.2 43.4 52.3 49.9 26.9 51.7 46.7

M92-237

63.1 50.6 42.1 48.5 31.9 51.1 47.2

M92-085

63.3 48.7 41.2 50.0 29.4 50.8 46.5

M92-217

35.7 49.3 48.8 55.2 25.3 47.3 42.9

Lambert

69.6 31.7 29.4 53.6 35.2 46.1 43.9

Agassiz

62.4 36.3 38.6 46.0 21.7 45.8 41.0

M92-223

45.6 55.3 34.5 45.5 20.9 45.2 40.4

M92-239

47.8 42.2 44.4 42.0 23.5 44.1 40.0

Gnome 85

67.0 32.6 25.3 41.8 23.9 41.7 38.1

OR-8

66.3 34.0 22.1 34.2 13.6 39.2 34.0

OR-6

58.2 28.2 25.3 43.6 33.1 38.8 37.7

Sibley

64.3 24.0 18.4 29.7 14.8 34.1 30.2

Evans

68.6 13.2 14.2 29.9 25.0 31.5 30.2

Commercial cultivar average

65.2 28.6 24.8 39.8 23.9 50.5 36.4

Ontario line average

56.9 49.4 47 48.5 30.8 39.6 46.5

Table 3. Maturity (days from emergence), lodging (0-10) and height (cm) of soybean lines, 1994 -1998. Cultivars are ranked by 1994 -1997 average yield. Malheur Experiment Station, Oregon State University, Ontario, OR, 1998.

Cultivar 1994 1995 1996 1997 1998
Maturity Lodging Height Maturity Lodging Height Maturity Lodging Height Maturity Lodging Height Maturity Lodging Height
M92-314 100 0 80 106 0 55 90 0 74 112 0 80 137 0 56
M92-220 107 4 102 123 0 80 115 2 80 112 0 85 121 0 60
M92-350 107 7 106 106 8 105 90 9 79 100 0 100 115 0 64
M92-330 100 1 101 98 2 95 90 0 74 100 0 65 115 0 46
M92-225 93 5 92 106 0 80 90 1 76 100 0 60 115 0 42
M92-213 107 0 70 123 0 80 105 0 80 112 0 100 128 0 70
M92-237 100 5 106 106 0 95 90 0 88 100 0 70 115 0 49
M92-085 93 2 102 106 0 95 105 6 70 100 0 80 115 0 56
M92-217 107 0 68 115 0 75 105 0 86 112 0 80 137 0 55
Lambert 107 9 112 129 6 85 126 7 81 112 6 105 132 9 71
Agassiz 102 7 105 123 5 100 98 6 76 112 3 70 132 6 62
M92-223 107 0 65 115 0 65 115 0 70 114 4 110 132 3 55
M92-239 107 0 67 106 0 55 105 0 85 112 0 65 128 0 46
Gnome 85 102 8 105 123 6 100 105 8 90 112 7 100 132 9 72
OR-8 120 10 96 129 7 100 126 7 78 120 8 105 137 7 74
OR-6 100 9 107 106 2 100 98 9 97 112 3 85 115 8 60
Sibley 114 10 110 125 8 90 126 7 75 120 9 60 137 9 42
Evans 107 9 105 123 8 110 126 8 70 120 8 100 137 10 69