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Photosynthate partitioning in diploid and autotetraploid barley ( Hordeum vulgare )
Author(s) -
Sicher Richard C.,
Kremer Diane F.,
Harris William G.,
Baenziger P. Stephen
Publication year - 1984
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1984.tb04571.x
Subject(s) - hordeum vulgare , tiller (botany) , biology , photosynthesis , dry weight , poaceae , cultivar , sucrose , botany , inflorescence , horticulture , agronomy , biochemistry
Net rates of carbon assimilation per unit leaf area by fully expanded, vegetative leaves of diploid (2x) and autotetraploid (4x) barley ( Hordeum vulgare L. cultivars OAC‐21 and Brant) were not significantly different (90% level) when measured under controlled environment conditions with air levels of CO 2 and either 2 or 20% O 2 . Leaf thickness increased with ploidy so that net photosynthetic rates measured on single leaves were lower for 4x than 2x barley varieties when compared on a dry or fresh weight basis. Rates of 14 CO 2 fixation by isolated mesophyll protoplasts prepared from seedlings were also lower for 4x than 2x varieties [about 108 and 125 μmol (mg ChI) −1 h −1 , respectively]. Carbohydrate accumulation in leaves of 5‐weekold plants averaged 28% (2x) and 47% (4x) of the total photosynthetic weight gain during the first 9 h of the light period. Estimated photoassimilate export from leaves was 15% (OAC‐21) and 38% (Brant) lower for 4x compared to 2x isolines. The sucrose and oligofructan content of 4x compared to 2x leaves increased as a result of decreased photosynthate transport. Total tiller dry weight of plants raised in a glasshouse was greater for 4x than 2x barley varieties at ear emergence, but tiller height decreased with increasing ploidy. The nonstructural carbohydrate content of the inflorescence, leaves and lower stem organs was significantly ( P ≤ 0.01) higher in 4x than in 2x lines at this sampling. During the first 15 days of grain development total tiller dry weight increased by 46% (2x) compared to 8% (4x) when the results of both varieties were averaged together. The dry weight gain of the ear during this period was about 60 to 80% lower for 4x compared to 2x isolines. The nonstructural carbohydrate content of the inflorescence was also about 24% (Brant) and 51% (OAC‐21) lower for 4x as compared to 2x plants 15 days post ear emergence. The above results suggested that photosynthate partitioning in autotetraploid barley was sink‐limited.