Biomass production and allocation in Jatropha curcas L. seedlings under different levels of drought stress

Abstract

In a greenhouse experiment we applied three levels of drought stress and monitored growth variables and biomass production of J. curcas seedlings propagated from three seed accessions. We determined biomass allocation, allometric relationships and plant traits. Well-watered J. curcas seedlings grew 0.81±0.15 cm day -1 in length and produced 1.49±0.31 g dry biomass day -1 . Under medium stress (40% plant available water) the plants maintained a similar stem shape, although they grew at lower rate (stem length: 0.28±0.11 cm day -1 ; dry biomass production: 0.64±0.18 g day -1 ). Seedlings under extreme drought stress (no irrigation) stopped growing, started shedding leaves and showed shrinking stem diameter from the 12 th day after the start of the drought treatment.The drought treatment did not influence the wood density (0.26 g cm -3 ). The root/shoot ratio of the wet treatment was 0.27, which is low compared to other tropical trees. Both 3

Root growth in Jatropha and its implications for drought adaptation

“…This is within the range reported by Achten et al [19] on root/shoot ratio for 104 day old seedlings in different soil water deficit regimes (0.41 -0.27). These values were the least when ten other tropical deciduous woody and shrub species were compared [19].…”

“…This is within the range reported by Achten et al [19] on root/shoot ratio for 104 day old seedlings in different soil water deficit regimes (0.41 -0.27). These values were the least when ten other tropical deciduous woody and shrub species were compared [19]. However, the root/ total plant ratio was reduced to a mere 0.03 when the tap root portion from 0 to 30 cm soil depth was not included, indicating that very little root biomass is devoted to absorption of soil moisture or nutrients.…”

“…Again, a low ratio of transpiration crop coefficients (0.51 to 0.60) compared to the reference crop [19] and a limited (0.51 -0.70) stem sap flow ratio of adult plants [20,19] support the rating of conservative water use of Jatropha. The extent of leaf drop and timing is known to be acutely sensitive to the intensity of drought [6,19].…”

“…The extent of leaf drop and timing is known to be acutely sensitive to the intensity of drought [6,19]. The retained leaves often exhibit parahelionasty as a drought response and change the anatomy of the new leaves to suit the low water availability.…”

Photosynthesis and antioxidant activity in Jatropha curcas L. under salt stress

“…Its seeds contain 25 to 32% oil (Pompelli et al, 2010b), with yields of 1.5 tons of oil per hectare after five years of growth (Openshaw, 2000;Tiwari et al, 2007;King et al, 2009). Furthermore, J. curcas is well-adjusted to semiarid climate, although more humid environmental conditions result in better crop performance (Foidl et al, 1996;Openshaw, 2000;Tiwari et al, 2007;Maes et al, 2009;Achten et al, 2010;Behera et al, 2010;Pompelli et al, 2010a;Reubens et al, 2011). These promising characteristics of J. curcas have resulted in numerous plantation initiatives in the semiarid tropics (Behera et al, 2010).…”