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Juvenile Growth in Pigeonpea, Soybean, and Cowpea in Relation to Seed and Seedling Characteristics 1
Author(s) -
Brakke M. P.,
Gardner F. P.
Publication year - 1987
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1987.0011183x002700020038x
Subject(s) - seedling , biology , cajanus , vigna , shoot , dry matter , agronomy , sowing , horticulture
Pigeonpea ( Cajanus cajan L. Millsp.) is characterized by a weak seedling and juvenile growth, and slow establishment. This study evaluated growth parameters influencing seedling and juvenile growth of pigeonpea compared to grain legumes more vigorous in juvenility, viz., cowpea ( Vigna unguiculata L.) and soybean [ Glycine max (L.) Merr.]. The hypothesis that slow juvenile growth in pigeonpea is due to disproportionate assimilate partitioning to roots resulting in less shoot growth was tested also. Total shoot and root dry matter (DM) and leaf area (LA) were sampled weekly on field‐grown potted plants for 49 days after planting (DAP) in 1983. Dry matter and LA were consistently fourfold to sixfold greater for soybean and cowpea than pigeonpea at each weekly sampling. Shoot/root ratios for the three legumes were similar in trend and magnitude; hence the hypothesis of disproportionate partitioning and root growth was not accepted. Pigeonpea seedlings without exposed cotyledons (hypogenous) had smaller unifoliolate and trifoliolate leaves than the epigenous soybean and cowpea. At 10 DAP, relative leaf area for cowpea, soybean, and pigeonpea was 100, 65, and 20%, respectively. Relative DM yield was 100, 64, and 27%, respectively. However, relative (not absolute) leaf‐ and plant‐growth rates during the time course were significantly greater for pigeonpea than for soybean and cowpea. Nodule formation in pigeonpea was reduced compared to the other legumes. Utilization of seed energy was more rapid in cowpea at 10 DAP than for pigeonpea, but the two were similar at 17 DAP. Seed energy conversion efficiency was similar for cowpea and pigeonpea at both sampling dates. Size of seedling axis was related to seedlingrowth. We conclude that pigeonpea plant type might be improved by larger seeds and cotyledons, epigeal emergence, and larger unifoliolate and trifoliolate lamina during seedling and juvenile growth phases.