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Forage Quality Responses of C 3 and C 4 Perennial Grasses to Shade
Author(s) -
Kephart Kevin D.,
Buxton Dwayne R.
Publication year - 1993
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/cropsci1993.0011183x003300040040x
Subject(s) - panicum virgatum , phalaris arundinacea , biology , festuca arundinacea , panicum , perennial plant , forage , agronomy , neutral detergent fiber , poaceae , andropogon , bromus , fodder , dactylis glomerata , festuca , photosynthesis , bromus inermis , botany , bioenergy , ecology , wetland , renewable energy
Both C 3 and C 4 grasses exhibit similar morphological responses to shade, but they differ in photosynthesis‐related responses to shade, such as forage yield and growth rate. Morphological adaptation and reduced photosynthesis under shade may affect forage quality. The objective of this research was to determine the effect of adaptation to shade on forage quality of C 3 and C 4 grasses. The C 3 species were tall fescue ( Festuca arundinacea Schreb.), reed canary grass ( Phalaris arundinacea L.), and deertongue grass ( Panicum clandestinum L.); the C 4 species were switchgrass( Panicum virgatum Michx.) and big bluestem ( Andropogon gerardii Vit.). Grasses were established near Ames, IA, and grown under shade cloths which allowed 37 and 70% of ambient sunlight (AS) to penetrate. In addition, the grasses were subjected to a nonshaded (100% AS) treatment. Leaf blades, nonlaminar herbage, and total herbage samples were obtained at approximately 21‐d increments from late spring to early summer for 2 yr. Neutral‐detergent fiber (NDF) concentration in leaf blades was 18% greater in C 4 species than in C 3 species. Otherwise, few clear differences were observed between C 3 and C 4 types. Compared with the 100% AS treatment, NDF concentration in the 37% AS treatment was reduced 2 to 3%, whereas N concentration was increased by about 31% in nonlaminar herbage. In vitro digestible dry matter was increased 3 to 5% by shade. Nitrogen content per unit leaf area was not affected by shade, suggesting that nitrogenous compounds were concentrated by thinning of leaves. Thus, stressful growth conditions that limit photosynthate, such as shade, may improve forage quality.