PNL Volume 19 1987 RESEARCH REPORTS 55
UPDATE, PISUM GERMPLASM AND PEA SEEDBORNE MOSAIC VIRUS IN
NORTHERN INDIA, 1987
Rishi, N. Harvana Agricultural University, Hisar, India
and Hampton, R. 0. USDA, Agricultural Research Service
Oregon State University, Corvallis, OR USA
Northern India was previously reported (1,2) as a principal
site from which pea seedborne mosaic virus (PSbMV) had been dis-
tributed into Pisum germplasm collections. At the same time (2),
Northern India had been the world's richest resource of PSbMV-
immune accessions (genotype sbm/sbm). We have since surveyed pea
plantings over a 2500 km expanse of Northern India (Jammu and
Kashmir, Hamachal Pradesh, Haryana, Rajasthan, Haryana, Delhi, and
Uttar Pradesh) for both PSbMV occurrence and Pisum germplasm di-
versity during December 1985, February 1986, June 1986 (higher
elevations), and 11-22 February 1987 (when second author visited
India). We herein report the results of this survey.
Sweeping changes in diversity. There has been a drastic
reduction in Pisum germplasm diversity in this extensive pea-
growing area since the 1960's when the last collections of Nor-
thern India germplasm were made. The many hundreds of "local
varieties" (landrace equivalents) grown in Northern India prior to
1970 have since been replaced by a few grain-type cultivars (prin-
cipally 'Rachna' and 'T-163' developed at Agricultural University,
Kanpur) and a few vegetable-type cultivars (principally 'Arkel'
and 'Bonneville'). Simultaneously, whereas Northern India's
1,000,000 ha pea crop had previously consisted of grain-type
"local varieties", as many as 487,000 ha are now planted to the
above vegetable types, marketed as green pods by individual far-
mers.
In a single stroke, as it were, revolutionary changes in Nor-
thern India pea plantings have produced several remarkable re-
sults: (a) yields and farm profits have risen dramatically, (b)
the field incidence of PSbMV has been reduced, and (c) a vast
Pisum germplasm resource has been supplanted, probably in many
cases irretrievably. Fortunately, Pisum collections (19 57-61) by
Walter Koelz, H. S. Gentry, and J. R. Harlan, USDA plant explorers
(Table 1) had included many locations in India. Likewise, the
Indian Agricultural Research Institute (IARI) had preserved a much
larger collection of Pisum germplasm, principally from Uttar
Pradesh, during the 1950's-60's. Some 472 accessions from the
IARI collection were presented in 1970 to the USDA Plant Introdui
tion Station, Geneva, New York, by Dr. H. B. Singh. Notwithstan-
ding the presence of PSbMV in many of these accessions (2), much
of this germplasm is being preserved in either IARI or USDA Pisum
collections. An official USA/Canadian working group has now been
authorized by USDA Agricultural Research Service and the Pisum
Crop Advisory Committee to derive PSbMV-free sources from this
valuable germplasm.
Field survey results. During rather painstaking field sur-
veys in locations representative of the Northern India pea-producing
region, we observed no plants of the above cultivars with obvious
PSbM symptoms. Nevertheless, some 45 plants were sampled for sub-
56
PNL Volume 19 1987 RESEARCH REPORTS
sequent laboratory tests. None of these samples contained ELISA-
detectable PSbMV. Of the districts surveyed, we observed plan-
tings of only three old-time "local varieties" each harvested for
grain use. Two in the Banaras District were tall, white-flowered
types, and one in the Gorakhpur and Sultanpur Districts was a
dwarf, purple-flowered type.
Experimental plot results. During 1986, samples were col-
lected from 242 Northern India seedlots of Arkel, Bonneville,
Rachna, 'T-163', 'RPG-3' and '44-21', and "nameless varieties".
Seed sources consisted of small farmers and local, state, and
national seed companies. Fifty to 300 seeds from each seedlot
were space-planted 9 December 1986 in plots at Haryana Agricul-
tural University. The resulting plants were observed in February
1987, and visual PSbM-symptom scores were ascribed to each plant.
From these, plants representing three symptom-severity categories
and several symptomless plants were sampled for preliminary tests
by ELISA. A perfect correlation resulted between plants with con-
spicuous PSbM-like symptoms and positive tests for PSbMV by ELISA.
Uniform PSbMV symptoms in the foliage of all plant nodes in ex-
perimental plots suggested that infected plants arose primarily
from PSbMV-infected seeds.
Subsequently, plants from 132 seedlots were selected for
PSbMV tests by ELISA. One or more plants from 52 seedlots were
determined by ELISA to contain PSbMV (Table 2). Seedlots of most
"nameless varieties" were kindly provided from private seed sup-
plies of small farmers. Several significant points are apparent.
Thirty-nine percent (52/132) of the Northern India pea seedlots
tested by ELISA contained detectable PSbMV. The proportion of
PSbMV-infected "nameless variety" seedlots (34/56=61%), however,
was almost three times the proportion of infected named-cultivar
seedlots (17/76=22%). Relatively healthy seed sources of major
pea cultivars were readily available, providing definite potential
for crop improvement through seed-stock assays and selection. On
the basis of both visual observations and ELISA results, 12 sour-
ces of cv. Arkel, 12 sources of cv. Bonneville, and four sources
each of cvs. 44-22 and RPG 3 were free of detectable PSbMV.
The confirmed occurrence of PSbMV in 52/132 Northern India
seedlots suggest (a) that PSbMV had been readily aphid-transmitted
in recent years from old-time "local varieties" to the supplanting
named cultivars, and (b) that PSbMV-infected plants of both grain
and vegetable cultivars may have lost competitive ability (PSbMV—
induced plant stunting) against healthy plants in the field, thus
escaping our survey observations at or beyond the bloom stage.
Under February 1987 survey conditions, there was no evidence of
PSbMV spread to healthy plants by aphid vectors, i.e. no plants
with PSbM-like symptoms were observed in the upper plant canopy of
the fields surveyed.
Observations. By decision of the All-India Coordinating
Program, all pea lines henceforth released for commercial produc-
tion in India must be powdery-mildew resistant. Superior powdery-
mildew-resistant lines of both grain and vegetable types were ob-
served at several trials/demonstrations in Uttar Pradesh, but par-
ticularly in the breeding plots of Dr. R. M. Singh, Banaras Hindu
University, Varanasi. Dr. Singh and colleagues have made note-
PNL Volume 19 1987 RESEARCH REPORTS
57
worthy use of both novel and conventional Pisum germplasm. The
near-future potential for superior, high yielding peas for Nor-
thern India appears to be very promising.
The concept of edible pods had not yet gained the interest of
pea breeders in India. Increasingly eager acceptance of freshly
harv ested peas—in—the—pod by the Northern India metropolitan mar-
kets, however, suggests that zero-waste, powdery-mildew-resistant,
edible-podded peas would be instantly successful there.
1. Hampton, R. 0. and S. W. Braverman. 1979. Plant Dis. Reptr.
63:95-99.
2. Hampton, R. 0. 1986. PNL 18:22-26.
Table 1. 1937-70 Pisum collections from India reposited 1/
at the USDA Plant Introduction Station, NYS Agricultural
Experiment Station, Geneva, NY.
Year of
collection
Plant
explorer
Number of
accessions
Description of
area sampled
1937
W. Koelz
7
Whole subcontinent
1948
W. Koelz
21
Whole subcontinent
1949
W. Koelz
20
Whole subcontinent
1953
H. Gentry
2
Bombay (market)
1954
H. Gentry
3
IARI; Delhi (market)
1961
J. Harlan
2
Palanpur (market)
1970
H. B. Singh 2/ 472
Principally Northern India
1/- Access-ions available in 1982.
2/- Presented to USDA Plant Inventory, in behalf of the Indian
Agricultural Research Institute, by Dr. H. B. Singh.
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PNL Volume 19 1987 RESEARCH REPORTS
Table 2. Incidence of PSbMV in selected Northern India pea seedlots,
determined by ELISA serology.
Seedlot origin
Cultivar
No. seedlots
PSbMV-infected,
ELISA results
No.
seedlots
tested
Jaipur, Rajasthan
Bonneville
Rachna
44-21
RPG 3
T-163
Nameless var. 1/
0
1
0
0
2
22
4
4
4
4
4
36
Ambala, Haryana
Ark el
Bonneville
Nameless var.
3
0
1
4
8
4
Hisar, Haryana
Bonneville
11
28
Jind, Haryana
Arkel
0
4
Karnel , Haryana
Nameless var.
2
4
Kurukshetra,
Haryana
Arkel
Nameless var.
0
9
8
12
Bareilly,
Uttar Pradesh
T-163
1
4
Total
52
132
1/- Seed samples provided from farmers' private seed supplies.
*****