Response of sugar beet (Beta vulgaris L.) yield and biochemical composition to elevated CO₂ and temperature at two nitrogen applications

Abstract

Effects on sugar beet (Beta vulgaris L.) of current and elevated CO 2 and temperature alone and in combination and their interactions with abundant and deficient nitrogen supply (HN and LN, respectively) have been studied in three experiments in 1993, 1994 and 1995. Averaged over all experiments, elevated CO 2 (600 µmol mol -1 in 1993 and 700 µmol mol -1 in 1994 and 1995) increased total dry mass at final harvest by 21% (95% confidence interval (CI) = 21, 22) and 11% (CI = 6, 15) and root dry mass by 26% (CI = 19, 32) and 12% (CI = 6, 18) for HN and LN plants, respectively. Warmer temperature decreased total dry mass by 11% (CI = -15, -7) and 9% (CI = -15, -5) and root dry mass by 7% (CI = -12, -2) and 7% (CI = -10, 0) for HN and LN plants, respectively. There was no significant interaction between temperature and CO 2 on total or root dry mass. Neither elevated CO 2 nor temperature significantly affected sucrose concentration per unit root dry mass. Concentrations of glycinebetaine and of amino acids, measured as α-amino-N, decreased in elevated CO 2 in both N applications; glycinebetaine by 13% (CI = -21, -5) and 16% (CI = -24, -8) and α-amino-N by 24% (CI = -36, -11) and 16% (CI = -26, -5) for HN and LN, respectively. Warmer temperature increased α-amino-N, by 76% (CI = 50, 107) for HN and 21% (CI = 7, 36) for LN plants, but not glycinebetaine.Key-words: Beta vulgaris; sugar beet; biomass; CO 2 ; nitrogen; root quality; temperature; yield. INTRODUCTIONAtmospheric CO 2 concentration (C a ) is expected to increase to between 600 and 700 µmol mol -1 by the end of the next century. Global temperatures are also expected to increase, perhaps by 3°C. Because photosynthesis and biomass production of plants with C 3 photosynthetic metabolism are currently limited by C a , both increase as C a rises reaching a maximum at about 700-1000 µmol mol -1 CO 2 (Cure & Acock 1986;Lawlor & Mitchell 1991;Idso & Idso 1994): on average the increase in biomass is 33% with a CO 2 rise from about 350 to 700 µmol mol -1 (Kimball 1983). Elevated CO 2 increases photosynthesis and decreases photorespiration due to the characteristics of ribulose bisphosphate carboxylase/oxygenase (Rubisco). However, the effect of warmer temperatures on Rubisco is to increase photorespiration and decrease photosynthesis. Thus, CO 2 concentration will interact positively with temperature (Long 1991;Stitt 1991;Lawlor & Keys 1993).Growth characteristics of plants, particularly the duration of growth and accumulation of assimilates in storage organs (e.g. tubers, roots or seeds), together with respiration, affect the use of photosynthates. If this 'sink capacity' is restricted, compared to assimilate production, then the potential advantages of increasing CO 2 for biomass and yield production may be limited. Sink demand is affected by environmental conditions; for example, warmer temperature stimulates growth rate and respiration so that sink limitation would be less -and so the effects of CO 2 enrichment greater -at warmer than at cooler temperatures ...

Growth, photosynthesis, and metabolism of sugar beet at an early stage of exposure to elevated CO2

“…A reduction of the ratio of root to shoot from 0.59 to 0.47 occurred solely due to the increase in the weight of shoots. In our experiments conducted in the phytothron, the increment in the biomass of sugar beet shoots (Table 1) was close to the total increase in the biomass of the whole plant (by 13−25%) observed by other researchers after a prolonged plant growth at 2C ‡ in a chamber of FACE type with an open top and recorded climatic parameters [17].…”

Nitrogen and carbon partitioning in soybean under variable nitrogen supplies and acclimation to the prolonged action of elevated CO2

“…Var i ous rea sons were given for re duced N con centra tion un der en riched CO 2 such as di lu tion by increased level of car bo hy drates or the re duc tion of N up take un der el e vated CO 2 or de creased rate of tran spi ra tion (Larigauderie et al 1988, Hock ing and Meyer 1985, Uprety and Rabha 1999, Srivastava et al 2001. De scrip tive stud ies on the in ter ac tion be tween el e vated CO 2 and vari able N sup plies on crop like sugar beet (Demmers -Derks et al 1998), to bacco (Gei ger et al 1999), rice (Aben et al 1999) and cot ton (Prior et al 1998;Bro ker et al 2000) fur ther sug gested that high CO 2 may in crease the rubisco ef fi ciency and cause mobi li za tion of N from ex cess rubisco to the grow ing plant sinks for their growth and de vel op ment (Theobald et al 1998). These changes in plant metab o lism may af fect the crit i cal re quire ment of N to sup port max i mum dry mat ter pro duc tion.…”

Melas Uygulamalarının Şeker Pancarında (Beta vulgaris L.) Kök Verimi ve Şeker Oranı Üzerine Etkilerinin Belirlenmesi

“…High daytime temperatures could also lower root yield and yield reduction was attributed to stomatal closure by reducing photosynthesis and increasing respiration (Cooke and Scott 1995). Warmer temperatures accelerate development and early growth but have a negative effect on final biomass, due to canopy senescence and increase in maintenance respiration (Demmers-Derks et al 1998). Molasses is used primarily as a source of K. It also contains secondary elements in small quantities such as P, S, Ca, Mg and numerous trace elements.…”