Number of cells and mean cell volume of strawberry receptacles were determined throughout the development of secondary fruit of three day-neutral cultivars grown in a greenhouse. Receptacle tissue was digested with pectinase and cellulase and number of cells determined with a Batch counting chamber. Cultivars differed in fruit size throughout development. The size of ripe fruit was small (3.8 g) in `Tillikum', medium (11.6 g) in `TriStar', and large (15.6 g) in `Selva'. Cell division continued in all cultivars for 15 days after anthesis (DAA) and was exponential during the first 10 days. The number of cell per fruit after 15 DAA averaged 0.71, 1.96, and 2.94×106 for `Tillikum', `TriStar', and `Selva' respectively. Mean cell volume, as estimated from number of cells and volume of receptacle tissue, increased rapidly between 10 and 25 DAA. Cells of the pith were larger than those of the cortex during early fruit development. Mean cell volume of mature fruit was approximately 6×106 μm3 in the three cultivars. Genotypic variation in fruit size was primarily due to the difference in number of receptacle cells.
G.W. Cheng and P.J. Breen
Joel G. Reiten, Chiwon W. Lee, Z.M. Cheng and Ronald C. Smith
Seeds of a Kentucky bluegrass cultivar (Poa pratensis 'SD Common') and two native buffalograss (Buchloe dactyloides) strains, Texas (TX) selection and North Dakota (ND) selection, were tested for their germination tolerance to increasing levels of NaCl at 0, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.2, 1.6, 2.0, 2.4, 2.8, 3.2% in solution. Both the TX and ND strains of buffalograss exhibited a high degree of salt tolerance with the upper limit of seed germination at 2.8% NaCl (2% to 7% germination after 6 days). At high NaCl concentrations, however, percent seed germination was much greater in the ND strain than the TX strain of buffalograss. For instance, seed germination at 0.8% NaCl was 90% in ND strain and 53% in TX strain as compared to the control. Kentucky bluegrass was least tolerant to NaCl with the upper limit of seed germination at 0.4% NaCl (14.7% germination in 6 days). Seed germination in Kentucky bluegrass was completely inhibited at 0.6% NaCl.