Because tuberization in potatoes (Solarium tuberosum L.) reportedly is inhibited when stolons are immersed in liquid, this study was conducted to determine the effect of intermittent pH reductions of the nutrient solution on tuber induction of potatoes in solution culture. Tissue-culture potato plantlets were transplanted into solutions maintained at pH 5.5. The pH of the nutrient solution was changed to 3.5 and 4.0 for 10 hours on each of three dates (30, 35, and 40 days after transplanting). For the pH 3.5 treatment, tubers were observed first on day 42 and averaged 140 tubers per plant at harvest on day 54. For the pH 4.0 treatment, tubers were observed first on day 48 and averaged 40 tubers per plant at harvest. At a constant pH 5.5, tubers were observed on day 52 and averaged two tubers per plant at harvest. Plants with the intermittent pH 3.5 had smaller shoots and roots with shorter and thicker stolons compared to constant pH 5.5. With the intermittent pH 4.0, plants were of similar size, but stolons were shorter and slightly thickener compared to those from pH 5.5. Mineral composition of leaf tissues at harvest was similar for the three pH treatments. These results indicate that regulation of solution pH can be a useful technique for inducing tuberization in potatoes.
Waylen Y. Wan, Weixing Cao and Theodore W. Tibbitts
Senay Ozgen and Jiwan P. Palta
Tuberization in potato is known to be under complex biochemical control involving hormones. A number of studies have provided evidence for a critical role of GA in tuberization. There is also evidence that GA in plants can be modulated by a Ca/calmodulin pathway. The purpose of the present study was to determine the influence of supplemental Ca fertilization on tuber size and tuber number. Plantlets of Solanum tuberosum `Russet Burbank' raised in tissue culture were planted in 20-L pots filled with sandy loam field soil with the pH of 6.9 and exchangeable soil Ca level of 350 ppm. All treatments received the same total amount of N (equivalent to the rate of 280 kg·ha-1). Four treatments were evaluated: nonsplit N (from ammonium nitrate), split N (from ammonium nitrate), split N+Ca (from calcium nitrate), split N+Ca (50% N from urea, 50% N from ammonium nitrate and Ca from calcium chloride). The total Ca was applied at the rate equivalent to 168 kg·ha-1 on a split schedule (equally split at four, six, eight and ten weeks after planting). Four months after planting tubers were harvested and evaluated. As expected tuber tissue Ca was increased by Ca application from 144 to 245 μg·g-1. In general, the two Ca treatments had significantly lower tuber number per plant as compared to the nonsplit and split N treatments. A plot of mean tuber Ca and tuber number for individual plants showed a significant negative relationship. Both Ca treatments produced tubers with higher mean tuber weight compared to nonsplit N. This increase in tuber size with Ca application was not apparent when compared with split N treatment. These results show that Ca application to soil can decrease tuber number suggesting that soil Ca may influence tuberization in potato.
Samuel Y.C. Essah, Jorge A. Delgado, Merlin Dillon and Richard Sparks
for potato following oat ( Avena sativa ), which is a cover crop with higher C:N ratio and lower potential to mineralize N. Neeteson (1988) found that at optimal N fertilizer rates, potato tuber yields were slightly lower following legumes. Results
Philip J. White, John E. Bradshaw, M. Finlay, B. Dale, Gavin Ramsay, John P. Hammond and Martin R. Broadley
trace elements such as Se and I if fertilized appropriately ( Broadley et al., 2006b ). Furthermore, because potato tubers have relatively high concentrations of organic compounds that stimulate the absorption of mineral micronutrients by humans such as
Vered Naor, Jaime Kigel and Meira Ziv
Tubers were kindly supplied by Mrs. Ziva Gilaad, Jordan Valley Research and Extension Center, Israel.
Richard O. Nyankanga, Ocen Modesto Olanya, Hans C. Wien, Ramzy El-Bedewy, John Karinga and Peter S. Ojiambo
Late blight, caused by Phytophthora infestans (Mont.) de Bary, accounts for significant losses in potato production worldwide ( Erwin and Ribeiro, 1996 ). The pathogen infects foliage and tubers resulting in tuber yield loss attributable to
Anish Malladi and Jacqueline K. Burns
—stomatal conductance ( g S ), 3) changes in photoperiod—tuberization, and 4) apical dominance—axillary bud outgrowth, this article describes some of the roles of PGRs in communication between roots and shoots in horticultural crops. These four examples present
David Douches, Walter Pett, Diedrich Visser, Joseph Coombs, Kelly Zarka, Kimberly Felcher, Gurling Bothma, Johan Brink, Muffy Koch and Hector Quemada
Potato tuber moth is a serious pest of potato in South Africa. This insect causes damage during the growing season and in potato storage. The life cycle of potato tuber moth can be completed within 20 to 30 d and there may be as many as 12
C.D. Stanley and B.K. Harbaugh
Sons and Daughters for supplying caladium tubers.
Etienne L. LeRiche, Gefu Wang-Pruski and Valtcho D. Zheljazkov
After-cooking darkening (ACD) is an undesirable potato tuber trait, problematic in processed potato products ( Wang-Pruski and Nowak, 2004 ). It is characterized as a change from a tuber's normal flesh color to gray, blue, purple, or black