Biomass tuber

Figure 17.10 Total biomass of potato plants grown under two PARs (400 and 800 pimol m s ), two CO2 concentrations (350 and 1000 ppm), and two photoperiods (12 and 24 h). Data are averages for three cultivars, Norland, Russet Burbank, and Denali, grown for 90 days. Tuber yields showed a similar response pattern to total biomass. CO2 enrichment showed the greatest proportionate benefit under the 12-h photoperiod and 400 pimol s PAR, and no benefit or even had a negative effect under 800 pimol s and 24 h lighting (Wheeler et al., 1991).

Herbivory in benthic marine systems is intense. For example, on coral reefs, herbivores can remove almost 100% of the biomass produced daily by marine macroalgae, whereas in the most intensely grazed terrestrial systems — African grasslands — herbivores only consume about 66% of the above-ground plant biomass.9-21-102 While terrestrial plants produce subterranean structures such as roots, bulbs, and tubers that are generally inaccessible to most animals, most marine algae do not... 

Rosa, M.F., Bartolemeu, M.L., Novais, J.M., and Sa-Correia, I., The Portuguese experience on the direct ethanolic fermentation of Jerusalem artichoke tubers, in Biomass for Energy, Industry, and Environment, 6th E.C. Conference, Grassi, G., Collina, A., and Zibetta, H., Eds., Elsevier Applied Science, London, 1992, pp. 546-550. 

Conde, J.R., Tenorio, J.L., Rodriguez-Maribona, R., Lansac, R., and Ayerbe, L., Effect of water stress on tuber and biomass productivity, in Topinambour (Jerusalem Artichoke), Report EUR 13405, Gosse, G. and Grassi, G., Eds., Commission of the European Communities (CEC), Luxembourg, 1988, pp. 59-64. 

The Jerusalem artichoke can reproduce by two primary means. It can reproduce and colonize an area by the allocation of photosynthate and nutrients into both asexual (tubers and, to a lesser extent, rhizomes) and sexual (seed) reproductive organs. Flexibility in the amount of resources allocated between sexual and asexual means of reproduction confers a selective advantage in that conditions that inhibit or block sexual production (lack of pollen, herbivory of floral structures, undesirable weather) allow increased allocation to asexual reproduction. Artificially reduced allocation of resources to sexual reproduction, for example, results in a substantial increase in those allocated to asexual means. With flower bud removal, more (82 vs. 69) and larger (4.4 vs. 3.8 g) tubers were formed per plant than those with unlimited sexual reproduction (Wesdey, 1993). Total biomass was not altered, potentially indicating a relatively complete diversion of resources to asexual reproduction when sexual reproduction is blocked. From a reproductive standpoint, the risk of making it to the next season is high with sexual reproduction and relatively low with asexual reproduction. Increased investment in tubers increases the opportunity for sexual reproduction in the future. 

The diameter of the head of the inflorescence ranges from 1.3 to 1.8 cm (six clones) and the mean number of seed per plant from 0.45 to 163 (Swanton, 1986). In wild clones, 9% of the biomass by the end of the season had been allocated to the flowers and fruit (Westley, 1993). If sexual reproduction was blocked, there was a substantial increase in biomass allocated to asexual means of reproduction in the form of more and larger tubers. Flowers in the late fall (November 1, Ontario, Canada) contained 2.46% N, 0.51% P, 2.02% K, 1.21% Ca2+, and 0.68% Mg2+ (Swanton and Cavers, 1989). 

In Jerusalem artichoke and other root and tuber crops, a significant portion of the total biomass at harvest is found in the underground storage organs (Kays, 1985 McLaurin et al., 1999 McLaurin and Kays, 1993 Meijer et al., 1993). The internal redistribution of carbon and nutrient elements that accumulate in the stems and leaves of Jerusalem artichoke plays an important role in the development of the tubers (McLaurin et al., 1999 Somda et al., 1999). Similar, but often more complex, accumulation and redistribution patterns occur for carbon and the mineral nutrient... 

In a French study, late cultivars (e.g., Violet de Rennes ) produced more total biomass than early cultivars (e.g., Blanc precoce ), but tuber yields were the same. The superior leaf area index of late cultivars could not be translated into superior tuber yields due to constraints on the life cycle as a result of unfavorable fall climatic conditions (Barloy, 1988b). Planting early in the spring ensures a longer growing season. In Southern Europe, this equates to February and not later than March. Later plantings result in reduced yields. 

Conde, J.R., Tonorio, J.L., Rodrfguez-Maribona, B., and Ayerbe, L, Tuber yield of Jerusalem artichoke (Helianthus tuberosus L.) in relation to water stress, Biomass Bioenergy, 1, 137-142, 1991. 

Jerusalem artichoke can grow in nutritionally poor soils with minimal cultivation. However, good agronomic practices considerably increase crop productivity. Practices that raise tuber and biomass yields include choice of cultivar, planting date, effective weed control, fertilization, irrigation, and good harvesting procedures. 

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