The effect of N source on `Kennebec' potato (Solanum tuberosum L.) tuberization was investigated using single-node segments originated from in vitro virus-free plantlets and inoculated on media with two nitrate: ammonia ratios (low, 2:1; high, 5:1). Cell count and size and sugar-use characteristics were measured at intervals of tuber development. Tubers grown on high nitrate-ammonia medium exhibited higher rates of sucrose use and higher dry-matter accumulation than tubers grown on low nitrate-ammonia medium. The median value of tuber fresh weight increased from 0.66 to 1.23 g as a result of increasing nitrate-ammonia. Significant differences in cell size and growth rate were observed between the two N treatments. There was also a high correlation between tuber cell size and dry matter (r = 0.82, P ≤ 0.05). These data demonstrate the importance of the nitrate: ammonium ratio in determining C use, tuber cell size, and tuber weight. Chemical names used: α-naphtylacetic acid (NAA); 6-benzylaminopurine (BA).
Junne-Jih Chen and Yu-Ju Liao
Junne-Jih Chen, Yung-Wei Sun, and Tzay-Fa Sheen
Seedlings of tomato (Lycopersicon esculentum Mill.) and cabbage (Brassica oleracea L. var. Capitata) were planted in 240-cell plug trays in the greenhouse and subjected to irrigation with water at different temperatures once a day. Irrigation with cold (5 to 15 °C) water reduced stem length of tomato by 28% to 32% in comparison with irrigation with water at room temperature (27.5 to 30.5 °C). Use of water at 10 °C did not affect total shoot dry weight but increased the shoot dry weight per centimeter of stem. Irrigation with water at 5 °C reduced stem length of cabbage seedlings 40%, but use of water at 10 and 15 °C did not. Both shoot and root dry weights were increased by irrigation with water at 10 °C. These results demonstrate that irrigation with cold water provides an effective method for improving the quality of plug-grown seedlings.
Junne-Jih Chen, Ming-Chung Liu, and Yang-Hsiu Ho
Tuber production of calla lily (Zantedeschia elliottiana Spreng cv. Super Gold) was investigated using three size ranges (7-10, 4-7, and <4 mm shoot diameter) of in vitro plantlets acclimated in either pots or soil beds in a protected house. The shoots and tubers of large plantlets exhibited higher rates of dry-matter accumulation than did those of small plantlets. The diameter of tubers harvested from pots ranged from 0.67 to 4.1 cm with median values of 2.7, 2.1, and 1.9 cm for the plants derived from large, medium, and small plantlets, respectively. Plants grown in soil beds, regardless of size, produced larger tubers than did those grown in pots. Tubers >3 cm in diameter developed on 25% and 52% of plants grown in pots and soil beds, respectively. Our results suggest that improved calla lily production could be realized by using larger in vitro plantlets as the source material and growing them in soil beds in a protected house.