Relationship of photosynthesis and related traits to seed yield in oilseed Brassicas

The physiological basis of yield in oilseeds Brassicas needs to be investigated, and the contribution of these traits to its yield is difficult to decipher. Eight cultivars of Brassica belonging to 3 species viz. B. juncea, B. napus and B. carinata - based on significant differences in yield were tested over two years. Net photosynthesis, transpiration, stomatal conductance and water use efficiency were investigated on 3rd and 4th fully expanded leaf on the main stem and related to yield. Average photosynthetic efficiency (umolm-2s-1) was higher in RLC1 (36.1), GSC6(36.3) and PC5 (33.8) cultivars. Impact of environment was inconspicuous. However interactions (GxY) were significant for the studied photosynthetic traits except Pn. Lower transpiration rates were associated with higher water use efficiency in RLC1 (5.69), GSL1 (5.44) and GSC6 (5.40). Positive correlation between SY and Pn (0.385) was recorded for the first time in Brassicas although the magnitude of association was low. Quality mustard cultivar (RLC1, B. juncea) and amongst B. napus GSC6 (canola) and Hyola PAC401 (hybrid, canola) were higher yielders due to relative high Pn, more efficient utilization of water and chlorophyll content. Indeterminate growth habits of the cultivars indicated highest contribution to Pn by leaves during flowering as compared with early siliquae formation. Environment had a profound impact on the yielding ability and the photosynthetic traits

Computation of Jacobi sums of order l^2 and 2l^2 with prime l

In this paper, we present the fast computational algorithms for the Jacobi sums of orders $l^2$ and $2l^{2}$ with odd prime $l$ by formulating them in terms of the minimum number of cyclotomic numbers of the corresponding orders. We also implement two additional algorithms to validate these formulae, which are also useful for the demonstration of the minimality of cyclotomic numbers required

Visualizing pair formation on the atomic scale in the high-Tc superconductor Bi2Sr2CaCu2O8+d

Pairing of electrons in conventional superconductors occurs at the superconducting transition temperature Tc, creating an energy gap D in the electronic density of states (DOS). In the high-Tc superconductors, a partial gap in the DOS exists for a range of temperatures above Tc. A key question is whether the gap in the DOS above Tc is associated with pairing, and what determines the temperature at which incoherent pairs form. Here we report the first spatially resolved measurements of gap formation in a high-Tc superconductor, measured on Bi2Sr2CaCu2O8+d samples with different Tc values (hole concentration of 0.12 to 0.22) using scanning tunnelling microscopy. Over a wide range of doping from 0.16 to 0.22 we find that pairing gaps nucleate in nanoscale regions above Tc. These regions proliferate as the temperature is lowered, resulting in a spatial distribution of gap sizes in the superconducting state. Despite the inhomogeneity, we find that every pairing gap develops locally at a temperature Tp, following the relation 2D/kBTp = 8. At very low doping (<0.14), systematic changes in the DOS indicate the presence of another phenomenon, which is unrelated and perhaps competes with electron pairing. Our observation of nanometre-sized pairing regions provides the missing microscopic basis for understanding recent reports of fluctuating superconducting response above Tc in hole-doped high-Tc copper oxide superconductors

Nanoscale Proximity Effect in the High Temperature Superconductor Bi-2212

High temperature cuprate superconductors exhibit extremely local nanoscale phenomena and strong sensitivity to doping. While other experiments have looked at nanoscale interfaces between layers of different dopings, we focus on the interplay between naturally inhomogeneous nanoscale regions. Using scanning tunneling microscopy to carefully track the same region of the sample as a function of temperature, we show that regions with weak superconductivity can persist to elevated temperatures if bordered by regions of strong superconductivity. This suggests that it may be possible to increase the maximum possible transition temperature by controlling the distribution of dopants.Comment: To appear in Physical Review Letter

Carrageenans from Red Seaweeds As Promoters of Growth and Elicitors of Defense Response in Plants

Plants incessantly encounter abiotic and biotic stresses that limit their growth and productivity. However, conversely, plant growth can also be induced by treatments with various abiotic and biotic elicitors. Carrageenans are sulfated linear polysaccharides that represent major cellular constituents of seaweeds belonging to red algae (Rhodophyta). Recent research has unraveled the biological activity of carrageenans and of their oligomeric forms, the oligo carrageenans (OCs), as promoters of plant growth and as elicitors of defense responses against pests and diseases. In this review, we discuss the molecular mechanisms by which carrageenans and OCs mediate plant growth and plant defense responses. Carrageenans and OCs improve plant growth by regulating various metabolic processes such as photosynthesis and ancillary pathways, cell division, purine and pyrimidine synthetic pathways as well as metabolic pathways involved in nitrogen and sulfur assimilation. Carrageenans and OCs also induce plant defense responses against viroids, viruses, bacteria, fungi and insects by modulating the activity of different defense pathways, including salicylate, jasmonate and ethylene signaling pathways. Further studies will likely substantiate the beneficial effects of carrageenans and of OCs on plant growth and plant defense responses and open new avenues for their use in agriculture and horticultural industry