Effect of tropospheric ozone and its protectants on gas exchange parameters, antioxidant enzymes and quality of Garlic (Allium sativum. L).

An experimental study was conducted to assess the detrimental effect of ground-level ozone (O3) on garlic physiology and to find out appropriate control measures against ground-level O3, at TNAU-Horticultural Research farm, Udhagamandalam. Elevated ground ozone levels significantly decreased garlic leaf chlorophyll, photosynthetic rate, stomatal conductance, total soluble solids and pungency. The garlic chlorophyll content was highest in ambient ozone level and lowest in elevated ozone@200 ppb, highest stomatal conductance was recorded in ambient ozone with foliar spray of 3%Panchagavya, and the lowest was observed in elevated ozone@200 ppb. Since the elevated O3 had reduced in garlic photosynthetic rate significantly the lowest was observed in elevated O3@200 ppb and the highest photosynthetic rate was observed in ambient Ozone with foliar spray 3% of panchagavya after a week. The antioxidant enzymes of garlic were increased with increased concentration of tropospheric ozone. The highest catalase (60.97 µg of H2O2/g of leaf) and peroxidase (9.13 ΔA/min/g of leaf) concentration was observed at 200 ppb elevated ozone level. Garlic pungency content was highest in ambient ozone with foliar spray of 0.1% ascorbic acid and the lowest was observed under elevated O3@200 ppb. Highest total soluble solids were observed in ambient ozone with foliar spray of 3%Panchagavya and the lowest observed in elevated ozone@200 ppb. Thus, tropospheric ozone has a detrimental impact on the physiology of crops, which reduced crop growth and yield. Under elevated O3 levels, ascorbic acid performed well followed by panchagavya and neem oil. The antioxidant such as catalase and peroxidase had positive correlation among themselves and had negative correlation with chlorophyll content, stomatal conductance, photosynthetic rate, pungency and TSS. The photosynthetic rate has high positive correlation with chlorophyll content, pungency and TSS. Correlation analysis confirmed the negative effects of tropospheric ozone and garlic gas exchange parameters and clove quality. The ozone protectants will reduce stomatal opening by which the entry of O3 in to the cell will be restricted and other hand they also will alleviate ROS and allied stresses.

Mitochondrial cytochrome oxidase (COI) sequence-based identification of pod borer of Thylacoptila sp. AA isolated from Senna alata (L.) Roxb. for the first time in India.

In the present study, two pod borer larvae were found to damage pods of the host plant Senna alata. As pods (seeds) are commercially important, it prompted the investigators to find out the adult of pod borer larvae by molecular sequencing and reported in this article for the first time from S. alata. Successful amplification was achieved for chloroplast DNA isolated from leaves of host plant S. alata and tissue DNA from unknown larvae and sequenced. The sequences were submitted to NCBI domain, and the taxonomic position of host plant of pod borer larvae was confirmed as S. alata (L.) Roxb. Of the two sequences belonging to pod borer larvae, specimen 1 (S1) matched with already available three sequences of Thylacoptila sp. AA. But, specimen 2 (S2) showed significant variation in its genetic distance in Neighborhood Joining tree and maximum likelihood tree; these factors imply that specimen 2 (S2) is distinct from Thylacoptila sp. AA. Therefore, it is reported that specimen 2 may be represented as Thylacoptila sp. BB where in BB indicates variant from other available sequences. Nonetheless, reporting species of Thylacoptila as insect pest in pods of S. alata is an important contribution to the annals of insect-pest-plant interaction more importantly in medicinally important plant species S. alata.