The effect of elevated carbon dioxide (600±50 cm3 m-3; C600) on growth performance, biomass production, and photosynthesis of Cenchrus ciliaris L. cv. 3108 was studied. This crop responded significantly by plant height, leaf length and width, and biomass production under C600. Leaf area index increased triple fold in the crops grown in the open top chamber with C600. The biomass production in term of fresh and dry biomass accumulation increased by 134.35 (fresh) and 193.34 (dry) % over the control (C360) condition where the crops were grown for 20 d. The rate of photosynthesis and stomatal conductance increased by 24.51 and 46.33 %, respectively, in C600 over C360 plants. In comparison with C360, the rate of transpiration decreased by 6.8 % under C600. Long-term exposure (120 d) to C600 enhanced photosynthetic water use efficiency by 34 %. Also the contents of chlorophylls a and b significantly increased in C600. Thus C. ciliaris grown in C600 throughout the crop season may produce more fodder in terms of green biomass. and R. K. Bhatt, M. J. Baig, H. S. Tiwari.
Three tropical range grasses (Cenchrus ciliaris, Dichanthium annulatum, and Panicum antidotale) and two range legumes [Macroptilium atropurpureum (siratro) and Stylosanthes hamata (stylo)] were grown under four irradiances, i.e. 100 (I100, control), 75 (I75), 50 (I50), and 25 (I25) % of full sunlight. Accumulation of chlorophyll (Chl) b increased but that of Chl a decreased under low irradiances. The greater accumulation of Chl (a+b) in grasses (particularly in D. annulatum and P. antidotale) under shade predicted their shade adaptability. Among legumes Stylosanthes was more adaptive to the shade than Macroptilium due to its higher accumulation of Chl (a+b). Significant difference in the accumulation of carotenoids under I25 over I100 was observed in all the species, which shows the increase in quality of the fodder under limited irradiance. There was a significant decrease in soluble protein content in C. ciliaris under I75, however, no significant difference in protein content was observed under I50 and I25, which was also reflected in the SDS pattern with the reduction in content of polypeptides at I75 and following increase at I50 and I25. This was possibly due to reduction of light-induced protein at I75 and then expression of the stress-induced protein at further reduction of irradiance. Peroxidase activity in C. ciliaris increased with the decrease in irradiance and its isozyme pattern showed differences among all treatments, which indicated the role of different peroxidase isoforms at different irradiances. and M. J. Baig ... [et al.].
At the vegetative growth stage (40 d), the mean photosynthetic rate (PN) and canopy photosynthesis (PN × LAI) in F1 hybrids and their parents were similar, whereas the maintenance respiration rate (RM) was considerably higher and PN/RM lower in the F1 hybrids than in the parents. Yet at the flowering stage, the hybrids showed higher PN and PN × LAI values, while RM and PN/RM were similar in both. A specific F1 hybrid like IR 62829A×Vajram showed high readings in PN, PN/RM, and PN × LAI at the flowering stage, while IR 62829A×Swarna followed by IR 62829A×Vajram had high values 40 d after planting. The parents Swarna and Vajram, although moderate in PN, had the highest PN × LAI at the flowering stage due to a greater LAI. and M. J. Baig, P. Swain, K. S. Murty.