Temperature tuber

Hartsema, A.M. (1961). Influence of temperature on flower formation and flowering of bulbous and tuberous plants. Handbuch der Pflanzenphysiologie, 16, 123-67. 

Preparation of Inulin. Comminute the tubers or roots in a food chopper or similar appliance and express the juice with a tincture press, using, if necessary, a small portion of water to complete the extraction. Heat the juice to 60-70° and add milk of lime to about pH 8. Filter and adjust the pH to 7 with oxalic acid. Heat to 70-80°, add activated carbon and filter. Allow the filtrate to stand quiescent overnight, during which time the inulin separates in the form of small spheroids. The yield may be increased by freezing the solution and allowing it to thaw at a low temperature. Filter and wash the inulin with abundant quantities of cold water. 

Chase CA, Sinclair TR, Locascio SJ (1999b) Effects of soil temperature and tuber depth on Cyperus spp. control. Weed Sci 47 467-472... 

Miles JE, Nishimoto RK, Kawabata O (1996) Diurnally alternating temperatures stimulate sprouting of purple nutsedge (Cyperus rotundus) tubers. Weed Sci 44 122-125 Miles JE, Kawabata O, Nishimoto RK (2002) Modeling purple nutsedge sprouting undersoil solarization. 

Yam tubers of Dioscorea alata (Umudike cultivar), D. rotundata (asukwu and obiaturugo cultivars)" and D. cayenensis (water yam and Nkokpu cultivars) were obtained from the National Root Crops Research Institute, Umudike, Nigeria. Some tubers were stored 6 or 12 months at room temperature (25-27 °C), some in vacuum dessicators over a suitable dessicant, and some in paper bags placed in a dark cabinet (absence of circulating air). Fresh tubers were peeled by carefully scraping away the cork layer to minimize loss of outer tissue since much of the protein is concentrated here ( ). They were then cut into 2 cu. cm. pieces, quickly frozen with solid CO2 in 50 9 portions in plastic bags, and stored in a freezer until needed. 

Because yams are stored in open systems at ambient temperatures (usually warm), tuber tissue was examined for proteinase activity at 40°C. Some tubers had high apparent polyphenol oxidase activity upon peeling of the tubers (tissue turned deep purple at the peeled surface) so that PYP was added to extracts to combine with polyphenolic compounds and protect the proteinase from reacting with these compounds. Earlier studies had shown some inhibition of alkaline proteinase activity by ferric ion (24) so that EDTA was also added to the extracts to chelate any free iron. Two alkaline pH optima were found, at 9.0 and 10.5. The alkaline proteinases of white potatoes (Solanum tuberosum) have pH optima between 8.6 and 9 (25) and those of Carilla chocola tubers have pH optima between 8.0 and 9.5 (26,27T, suggesting that alkaline... 

Fig. 2 shows fresh yams less than a month after harvest and a similar tuber after 4 months storage at ambient temperature (24-27°C) in open paper bags in a closed laboratory cabinet. The... 

Normal-phase TLC has been employed for the separation of two new flavans in the extract of the undergorund tubers of Cyperus conglomeratus Rottb. (family Cyperaceae). The underground tubes were dried, ground and were extracted with with petroleum ether diethyl ether-methanol (1 1 1, v/v) for 24 h at ambient temperature. The extract was defatted with cold methanol. The components of the extract were preliminarily separated by traditional column chromatography followed by GC/MS and TLC. New flavans (5-hydroxy-7,3, 5 -trimethoxyflavan and 5,7-hydroxy-3, 5 -dimethoxyflavan) were separated on silica TLC layers using petroleum ether-diethyl ether (1 3, v/v) with the RF values of 0.50 and 0.37 for dimethoxy and trimethoxy derivatives, respectively [115]. 

Lift crops during dry weather if possible, to prevent cross-infection of healthy tubers at harvest. Avoid wounding tubers. Never save tubers from infected plants for seed. Maintain storage temperatures at39°F (4°C) to inhibit new infections. 

An important factor determining the efficacy of radiation treatment of tubers and bulbs is the time delay between harvest and irradiation. The sprout inhibition is most pronounced if the irradiation of tubers and bulbs is applied shortly after harvest, when they are still in their dormancy stage. However, the dormancy period may vary among cultivars and cropping season, and is also dependent on the postharvest storage temperature. 

Blenkinsop, R. W., Copp, L. J., Yada, R. Y, Marangoni, A. G. (2002). Changes in eompositional parameters of tubers of potato (Solanum tuberosum) during low-temperature storage and their relationship to ehip proeessing quality. Journal of Agricultural and Food Chemistry, 50,4545 553. 

Carputo, D., Cardi, T., Palta, J. P, Sirianni, P, Vega, S., Fruseiante, L. (2000b). Toleranee to low temperatures and tuber soft rot in hybrids between Solanum commersonii and Solanum tuberosum obtained through manipulation of ploidy and endosperm balanee number (EBN). Plant Breeding, 119, 127-130. 

The quality of potato tubers depends upon genetic, climatic, biotic, chemical, and edaphic factors varietal characteristics precipitation, temperature and sunshine conditions competition with other plants the use of chemicals and the physical, chemical, and biological properties of the soil, which influence the capacity of the crop to take up the necessary water and nutrients to ensure success. 

PME activity increased by about 65% in the fresh tubers after 20 min at 60° C, but after 60 min it declined to about 40% of its original value. At 60°C, PME in potato tissue (ev. Kennebec) appears to have a relatively short inactivation time, or possibly its optimum activation temperature is <60°C. In this experiment also, PME aetivity deelined to less than 10% of its original value after 5 min at 70° C, and no aetivity at all was detected when the time at this temperature was prolonged. Similarly, no PME activity was detected in samples blanehed at 80°C. In potato tubers (cvs. Nicola and Irene), Van Dijk et al. (2002) found that the PME activity tended to remain eonstant during preheating at 60°C for 60 min. 

---