The leaves of 29-d-old plants of Brassica juncea Czern & Coss cv. Varuna were sprayed with 10-6 or 10-8 M aqueous solutions of indole-3-yl-acetic acid (IAA) or its substituted derivatives 4-Cl-IAA, 7-Cl-IAA, and 4,7-Cl2-IAA. All the auxins improved the vegetative growth and seed yield at harvest compared with those sprayed with de-ionised water (control). 4-Cl-IAA was most prominent in its effect, generating 21.6, 39.7, 61.0, 35.0, 65.5, and 56.2% higher values for dry mass, leaf chlorophyll content, carbonic anhydrase (E.C. 4.2.1.1) and nitrate reductase (E.C. 1.6.6.1) activities, net photosynthetic rate, and carboxylation efficiency, respectively, in 60-d-old plants. It also enhanced the seed yield by 31.1% over the control. The order of response of the plants to various auxins was 4-Cl IAA ≥ 7-Cl IAA > 4,7-Cl2 IAA = IAA > control.
Surface sterilised seeds of mungbean (Vigna radiata L. Wilczek cv. T-44) were soaked in 0, 10-8, 10-6, or 10-4 M aqueous solution of 28-homobrassinolide (HBR) for 4, 8, or 12 h. The treated seeds were grown in sandy loam soil filled in earthen pots and sampled at 30, 40, and 50 d. Net photosynthetic rate, leaf chlorophyll content, carbonic anhydrase activity (E.C. 4.2.1.1), carboxylation efficiency, stomatal conductance, and seed yield at harvest were enhanced by the HBR treatment. The best combination was the pre-sowing seed treatment with 10-6 M HBR for 8 h. and Q. Fariduddin, A. Ahmad, S. Hayat.
Young (12 years old) Norway spruce {Picea abies [L.] Karst.) trees were exposed to ambient CO2 or ambient + 350 |niiol(C02) moL' continuously over 2 growing seasons in open-top chambers, under field conditions of a mountain stand. Comprehesive analysis of CO2 assimílation was performed after 4 and 22 weeks of the second growing season to evaluate the influence of elevated atmospheric CO2. A combination of gas exchange and a mathematical model of ribulose-l,5-bisphosphate carboxylase/oxygenase (RuBPCO) activity was ušed. After 4 weeks of exposure no statistically significant stimulation of the radiant energy and CO2 saturated rate of CO2 uptake (ENsat) by the elevated CO2 concentration was found. Yet after 24 weeks a statistically significant depression of Ejvjsa, (38 %) and carboxylation efficiency (32 %) was observed. Depression of photosynthetic activity by elevated CO2 resulted from a decrease in the RuBPCO carboxylation rate. The electron transport rate was also modified similarly to the rate of RuBP formation. An accompanying decrease in nitrogen content of the needles (by 12 %) together with an increase in total saccharides (by 34 %) was observed after 24 weeks of exposure to enhanced CO2.
To investigate how bisulfite promotes photosynthesis, a pot experiment was conducted with rice (Oryza sativa L.) plants to determine Rubisco activity and content, and Rubisco activase (RCA) gene expression after spraying NaHSO3 on rice leaves. The NaHSO3 treatment promoted significantly net photosynthetic rate (PN), carboxylation efficiency, maximum carboxylation rate, ribulose-1,5-bisphosphate regeneration rate, initial Rubisco activity, and RCA protein and mRNA concentrations. Therefore, the NaHSO3 enhancement of PN could be directly attributed to induction of RCA gene expression both at the transcription and translation levels. Thus, the increased RCA regulated the initial Rubisco activity in vivo., Y. Chen, J.-H. Jin, Q.-S. Jiang, C.-L. Yu, J. Chen, L.-G Xu, D.-A. Jiang., and Obsahuje bibliografii
To explore the cause of difference in photosynthetic performance between different cultivars of crops, leaf net photosynt rate (PN) and photosystem 2 (PS2) photochemical efficiency (Fv/Fm), apparent quantum yield of carbon assimilation (φc), electron transport rate, photophosphorylation activity, etc. were measured in two soybean cultivars, Heinong 42 and Heinong 37. At pod setting and filling, significant differences in PN between them were observed. The former with a higher PN (from 7 to 38 %) had a significantly higher leaf thickness, leaf dry mass/area (LMA), chlorophyll content, soluble protein content, apparent quantum yield of electron transport through PS2 (φe), carboxylation efficiency (CE), and ribulose-1,5-bisphosphate carboxylase (RuBPC) activity. The significantly higher PN of Heinong 42 is mainly due to its higher content and activity of RuBPC. and Hua Jiang, Da-Quan Xu.