Assessment of gamma radiation through agro-morphological characters in camellia sinensis L. (O.) kuntze.

PURPOSE: To study the effects of gamma radiation on tea seed germination, morphological changes, and genetic variation by using gamma radiation. MATERIAL AND METHOD: Fresh Tea seed material were irradiated with twenty different doses of gamma radiation such as 0, 2, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80 90, 100, 200, 500 and 1000 Gy from Cobalt 60Co source from Regional Nuclear Agriculture Research Center, Bidhan Chandra Krishi Viswavidyalaya (BCKV), West Bengal, in between 2019 and 2020. RESULT AND CONCLUSION: The growth behavior of tea seedling was recorded under varying levels of gamma radiation and its performance at nursery stages. It was observed seed irradiated with doses from 35 Gy to 100 Gy could germinate but could not survive beyond five (05) months. When treated with higher doses as 200 Gy, 500 Gy and 1000 Gy, no seed germination takes places due to possible damages occur in the DNA structure. Screening of growth characteristics of tea plant generally monitored by the characteristics like plant height, number of leaves, number of primary branches, base diameter, and total leaf area of plants and we found that these characteristics significantly increased with the progress of time and increasing levels of gamma radiation; however, the plant height showed decreasing trend with the increasing levels of gamma radiation, which could be due to the change in chromosomal structure and genetic alteration. After 90 weeks of planting, the plant height, no. of primary branches, the number of leaves, plant base diameter, and total leaf area per plant recorded were 36.42 cm, 1/plant, 7.11/plant, 0.62 c.m, 22.92 cm2/plant respectively under the radiation level 30 Gy, whereas the corresponding figures of the above parameters at the control treatment were 85.32 cm, 1/plant, 18.84/plant, 1.18 c.m and 26.68 cm2/plant, respectively. The total plant height, no. of primary branches, the number of leaves, plant base diameter, and total leaf area per plant were significantly influenced by the rising levels of gamma radiation (up to 100 Gy), finally, after 90 weeks of planting, the maximum no. of branching was observed in the treatment of 8 Gy, 10 Gy and 15 Gy respectively. The study reveals a hitherto open the possibility of using gamma radiation on tea plant for creation of variation in the tea seed planting materials. Further studies on mutation using tea planting materials would give an insight into its mutable gene behavior.

Physiological and biochemical evaluation of high anthocyanin pigmented tea (Camellia sinensis L. O. Kuntze) germplasm for purple tea production.

Finding promising purple tea germplasm that would target new tea products for diversification and value addition boost the tea industry's economic growth. Accordingly, 10 tea germplasm viz. TRA St. 817, TRA St. 293, TRA St. 400, TRA 177/3, TRA 376/2, TRA 376/3, TRA 427/7, TRA P7, TRA P8, and TV1 were evaluated in terms of gas exchange parameters, multiplication performance, and biochemical markers such as chlorophyll, carotenoids, and anthocyanin content, which are related to the purple tea quality. The investigated gas exchange and biochemical parameters revealed significant differences. Germplasm TRA St.817 was physiologically more efficient (24.7 µmol m-2 s-1), followed by TRA St. 293, exhibiting the highest net photosynthesis, water use efficiency (19.02 µmol mmol-1), carboxylation efficiency (0.73), chlorophyll fluorescence or photochemical efficiency of PSII (0.754) and mesophyll efficiency (ci/gs ratio: 2.54). Net photosynthesis was positively correlated with water use efficiency, carboxylation efficiency, mesophyll efficiency, and photochemical efficiency of PSII (r = 0.965**, 0.937**, 0.857**, 0.867**; P = 0.05), respectively, but negatively correlated with the transpiration ratio (r = -0.878**; P = 0.05) based on Pearson correlation analysis. The total anthocyanin content (4764.19 µg.g-1 fresh leaf weight) and carotenoid content (3.825 mg.g-1 fresh leaf weight) were highest in the TRA St.817 germplasm, followed by germplasm TRA St. 293 (2926.18 µg.g-1 FW). In contrast, total chlorophyll content was significantly low (1.779 mg.g-1 fresh weight), which is very suitable for manufacturing purple tea. The highest carotenoid concentration in TRA St. 817 was 3.825 mg.g-1 FW, followed by TRA P8 (3.475 mg.g-1 FW), favoring the formation of more volatile flavor constituents. The promising germplasm, TRA St 817, has a multiplication success rate of 91.4% through cleft grafting. The outcome reveals that TRA St.817 is a promising germplasm that can be used to make speciality teas, i.e., purple tea.

Plant morphophysiological and anatomical factors associated with nitrous oxide flux from wheat (Triticum aestivum).

Experiments were conducted to study the dynamics of nitrous oxide (N2O) emission from wheat varieties viz., Sonalika, HUW 468, HUW 234 and DBW 14 grown in alluvial soils of North Bank Plain Agroclimatic Zone of Assam, India. Attempts were made to find out the relationship of N2O emission with plant morphophysiological, anatomical and soil properties. N2O fluxes from wheat varieties ranged from 40 µg N2O-N m⁻² h⁻¹ to 295 µg N2O-N m⁻² h⁻¹. Soil organic carbon and soil temperature have shown significant relationship with N2O flux. The rate of leaf transpiration recorded from the wheat varieties at different growth stages exhibited a positive correlation with N2O emission suggesting that movement of N2O along with the transpirational water flow may be an important mechanism of N2O transport and emission through wheat plants. Anatomical investigation by scanning electron microscope revealed that N2O emission has relationship with stomatal frequency of leaf and leaf sheaths. Variety HUW 234 with the highest stomatal frequency of leaf and leaf sheath also recorded higher seasonal N2O emission compared to other varieties. Seasonal N2O emission (E(sif)) of the varieties ranged from 3.25 to 3.81 kg N2O-N ha⁻¹. Significant variations in E(sif) values were recorded within the varieties.

Plant physiological and soil characteristics associated with methane and nitrous oxide emission from rice paddy.

Methane (CH4) and nitrous oxide (N2O) are important greenhouse gases causing global warming and climate change. Efforts were made to analyze the CH4 and N2O flux in relation to plant and soil factors from rice (Oryza sativa L.) paddy. Ten popularly grown rice varieties namely Rashmisali, Bogajoha, Basmuthi, Lalkalamdani, Choimora (traditional varieties); Mahsuri, Moniram, Kushal, Gitesh and Profulla (high yielding varieties = HYV) were grown during monsoon season of July 2006. The CH4 and N2O emissions were measured the date of transplanting onwards at weekly interval along with soil and plant parameters. The seasonal integrated CH4 and N2O emission (Esif) from rice ranged from 8.13 g m(-2) to 13.00 g m(-2) and 121.63 mg N2O-N m(-2) to 189.46 mg N2O-N m(-2), respectively. Variety Gitesh emitted less N2O and CH4 amongst all the rice varieties. Both CH4 and N2O emission exhibited a significant positive correlation with leaf area, leaf number, tiller number and root dry weight. Soil organic carbon of the experimental field was associated with both CH4 and N2O emission whereas nitrate-N content of soil was associated with N2O emission. Methane emission showed significant positive correlations with soil temperature and crop photosynthetic rate. Traditional rice varieties with profuse vegetative growth recorded higher CH4 and N2O fluxes compared to HYVs. Gitesh and Kushal having low seasonal CH4 and N2O emission with higher yield potential can be recommended as low greenhouse gas emitting rice varieties.

Methane emission characteristics and its relations with plant and soil parameters under irrigated rice ecosystem of northeast India.

Methane flux from rice varieties grown under two identical soils of Assam were monitored. In the first experiment, variety Jaya and GRT was grown in sandy loam soil of Lower Brahmaputra Valley Zone of Assam and the second experiment was conducted with variety Jyotiprasad and Bishnuprasad in sandy to sandy loam soils of Upper Brahmaputra Valley Zones of Assam. Methane flux recorded from variety Jyotiprasad and GRT was higher compared to variety Bishnuprasad and Jaya. The seasonal integrated flux recorded was 10.76 gm(-2), 9.98 gm(-2), 9.74 gm(-2) and 11.31 gm(-2) for variety GRT, Jaya, Bishnuprasad and Jyotiprasad, respectively. All the varieties exhibited two methane peaks one at maximum tillering stage and other at panicle initiation stage of the crop. Crop growth parameters such as leaf number, number of tillers and leaf area index (LAI) showed strong positive relationship with total methane flux. In both the experiments it was calculated that CH4 emission was substantially influenced by crop phenology and growth. This study emphasise the relationship of different growth parameters with methane emission.