Probir Kumar Pal

Effect of decapitation and nutrient applications on shoot branching, yield, and accumulation of secondary metabolites in leaves of Stevia rebaudiana Bertoni

The axillary buds of stevia (Stevia rebaudiana Bertoni) often remain dormant for a long time and sometimes remain dormant permanently until the plants enter into the reproductive stage. The present study was conducted to ascertain whether decapitation and foliar fertilization enhance the productivity and quality of stevia through breaking the apical dominance and increasing physiological activities. Ten treatment combinations comprising two cultural operations (non-decapitation and decapitation) and five foliar spray treatments (water spray control, KNO3 @ 5.0gL(-1), Ca(NO3)2 @ 4.06gL(-1), CuSO4·5H2O 2.0gL(-1) and (NH4)6Mo7O24 @ 1.0gL(-1)) were applied. The decapitation of apical buds of stevia increased the branches and increased dry leaf yield by 13 and 17% compared with non-decapitation during 2010 and 2011, respectively, without affecting quality. Foliar application of nutrient solutions also exerted a considerable effect on growth parameters, yield attributes and chlorophyll content, and significantly (P=0.05) higher dry leaf yield ranging from 8 to 26% over the control. Among the foliar spray treatments, KNO3 @ 5.0gL(-1) and Ca (NO3)2 4.06gL(-1) were found most effective in dry leaf yield. Thus, the decapitation of apical buds and foliar application of KNO3 and Ca (NO3)2 could enhance the productivity of stevia through improving the growth of axillary buds and physiological activities.

Evaluation, Genetic Diversity, Recent Development of Distillation Method, Challenges and Opportunities of Rosa damascena: A Review

Rosa damascena Mill that is one of the important species of Rosa is used for essential oil production. It is a tetraploid rose that belongs to Damask group of roses. It is generally thought that the R. damascena originated in the Neo-lithic period, in South Anatolia, as a hybridization of R. gallica and R. phoenicea. Nevertheless, the origin of R. damascena is a bone of contention throughout the world. So far, 400 volatile substances have been identified in rose oil. Besides its application in aromatic and food industries, some valuable characteristics of Damask rose oil such as anti - HIV, antibacterial and antioxidant activities have been established during last two decades. The demand of rose oil in international market is increasing, but the area of production is stagnant. Thus, there is a pressing need to extend the cultivation of R. damascena to larger area and to improve its production technology. Rosa damascena possesses vast diversity in plant habit and flower characteristics. Over all, the research publication on this crop is scarce compared to other crops. Hence, this review will provide the valuable information for further research and understanding of the crop and its value as an economical crop.

Evaluating the non-destructive method for determining the chlorophyll and nitrogen content in Stevia rebaudiana (Bertoni) leaf

Leaf chlorophyll (Chl) content is an indicator of photosynthetic activity, stress condition and nutritional status of a plant. The efficacy of a hand-held Chl meter (CCM-200) for non-destructive estimation of total Chl and nitrogen content in the stevia (Stevia rebaudiana Bertoni) leaves has been evaluated.

Non-destructive estimation of chlorophyll and nitrogen content in leaf of Rosa damascena (Mill)

Chlorophyll (Chl) and nitrogen (N) status of leaves provide valuable information about the physiological condition of plants. The conventional methods for measuring Chl and N contents in leaves are destructive, costly, time-consuming, and do not allow repetitive measurement of the same sample. The Damask Rose (Rosa damascena Mill) is an important aromatic crop in the western Himalaya region in India. Generally, flower yield and oil yield of the Damask rose are correlated with nitrogen, phosphorus, and potassium (NPK) levels in the leaf at the bud development stage. The dynamics of N within the rose plant have not been reported clearly. Thus, there is a pressing need for non-destructive techniques to estimate Chl and N content in the leaf of the Damask rose. Our objective was to establish an appropriate mathematical relationship between the Chl content index (CCI) value and the total Chl/N contents for non-destructive estimation of total Chl and N in the leaf of the Damask rose. The regression models were developed with destructively measured parameters (total Chl and N) as the dependent variable and a parameter derived from CCM-200 as the independent variable (CCI). We found that polynomial regression models are suitable for non-destructive estimation of total Chl, and the model predicted values were very close to traditionally measured values with a root mean square prediction error (RMSEp) less than 0.20 mg g−1 of Chl. In the case of N estimation, a power regression model was appropriate with lowest Akaikes information criteria (AIC) and root mean square validated error (RMSEv) value. Significant correlations (P ≤ 0.001) were observed between traditionally measured values and our model predicted values in both cases.

Pruning System and Foliar Application of MgSO4 Alter Yield and Secondary Metabolite Profile of Rosa damascena under Rainfed Acidic Conditions

Damask rose (Rosa damascena Mill.) is one of the most high-value essential oil-bearing plants in the world. However, the flower yield and quality of essential oil of R. damascena are largely influenced by the pruning practices and balanced supply of plant nutrition. The objective of this study was to test the hypothesis whether the pruning system and foliar fertilization of MgSO4 would influence the flower yield, growth and secondary metabolites profile of R. damascena. A field experiment of 10 treatment combinations comprising two pruning systems (complete and partial) and five levels of MgSO4 (water spray, MgSO4 @ 5.0g L-1, 10.0g L-1,15.0g L-1, and 20.0g L-1) was conducted. The experiment was conducted in randomized block design with factorial arrangement. Overall, the flower yield ranged from 503.66 to 1114.47 g bush-1, while oil content varied from 0.039 to 0.046% of the fresh flower. Irrespective of foliar spray, partial pruning produced significantly (P ≤ 0.05) higher flower yield (893.02 and 503.66 g bush-1) compared with complete pruning system in both the years. Regardless of pruning system, the foliar application of MgSO4 @ 15.0g L-1 registered about 26–38% higher flower yield compared with water spray control. The major constituents of essential oil were citronellol (19.75–48.88%), E-geraniol (9.63–29.6%), Z-citral (0.07–5.97%), nonadecane (6.76–22.32%), and heneicosane (2.87–10.21%). The principal component analysis revealed that the major hydrocarbons such as nonadecene, nonadecane, and heptadecane are positively and highly correlated with each others. The results suggest that higher yield and quality of R. damascena can be achieved through partial pruning system in combination with foliar application MgSO4 under rainfed acidic conditions.

Integrated Weed Management in Plantation Crops

Plantation crops are long-term crops established for commercial interest. Major plantation crops are tea (Camellia spp.), coffee (Coffea arabica L.), oil palm (Elaeis guineensis Jacq.), areca nut (Areca catechu L), cardamom (Elettaria cardamomum Maton and Amomum subulatum Roxb.), coconut (Cocos nucifera L.), cashew (Anacardium occidentale L.), cocoa (Theobroma cacao L.), and rubber (Hevea brasiliensis Mull. Arg.). Being long-term crops, and often grown as monocultures, plantation crops are severely infested with weeds. This chapter deals with the nature and effect of the weed menace in the above mentioned crops along with methods adopted for weed management. In the plantation crops, weeds are managed by physical, mechanical, and chemical methods similar to those generally adopted in arable/field crops. However, there are reports on the use of low-density polyethylene sheets for mulching interrow space and mowing between the rows to control weeds. Planting smother crops or leguminous cover crops and intercropping in the row space, and deploying grazing animals are the biological methods for weed management in some of these crops. Integrated approach involving a combination of cultural, mechanical, and biological weed control methods is also adopted for combating weeds in an effective, economical, and eco-friendly manner.