Chromium toxicity is considered as a major problem for agricultural soil that reduced crop productivity by affecting photosynthetic tissues. Exogenous application of melatonin can alleviate the adverse effects of chromium toxicity on plant growth. However, little is known about its effect on thylakoidal protein complexes responsible for conversion of solar energy to biochemical energy. Chlorophyll fluorescence a transients considered one of the best non-invasive and rapid method for the evaluation of photosynthetic (Photosystem II) efficiency of plants and plant health under environmental stress conditions. In the present study, three-week old plants of two canola cultivars AC-Excel and DGL were applied to melatonin (0, 1, 5, 10 μM) when grown under chromium stress (0, 50 and 100 μM) for further two weeks. Chromium stress reduced the growth (fresh and dry weights of shoots and roots) of both canola cultivars and exogenous application of 5 and 10 μM melatonin improved the growth of canola at 50 or 100 μM chromium stress. This improvement was greater in cv DGL than in AC-Excel. Increasing chromium decreased the photosynthetic pigments (chlorophyll a and chlorophyll b ). However, 5 and 10 μM melatonin application improved chlorophyll a at 50 μM chromium stress. Structural stability and efficiency of photosystem II (PSII) measured as performance index (PI ABS ) and ratios of fluorescence (Fv/Fm, Fv/Fo) Fv decreased due to chromium stress. JIP-test parameters showed that chromium stress increased the absorption and trapping fluxes with decrease in electron transport fluxes which caused the damage to reaction centers (RC), detachment of oxygen evolving complex (OEC) from RC or inefficiency of electron transfer from OEC to RC. Such adverse effects were greater in cv AC-Excel. However exogenous application of melatonin improved PI ABS , electron transport per reaction center (ET/RC), reduced variable fluorescence at J step (V J ) reflecting melatonin protected PSII from chromium stress induced damage by protecting OEC. Thus, OJIP fluorescence transients are quite helpful for understanding the intersystem electron transport beyond photosystem II in canola cultivars due to melatonin application under chromium stress. Findings Exogenous application of melatonin alleviated toxic effects of chromium on plant growth of canola by modulating photosynthesis, enhanced photosystem II efficiency and regulation of electron transport flux to protect photo-inhibition of PSII from oxidative damage.

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Rapid industrialization throughout the world during last few decades causing high chromium resulted widespread of agricultural soil contamination. The increased chromium contents beyond permissible level in some agricultural land areas increasing widespread concern about food safety.This study was carried out for evaluation of metal toxicity damage and its possible mitigation and improved photosynthetic efficiency by melatonin treatment in canola plants exposed to four melatonin levels (0,1,5,10µM) treated with chromium stress (0,50,100µM) for two days.Chlorophyll fluorescence a transients considered one of the best tool for photosynthetic (photosystem II) efficiency analysis of two canola cultivars Ac-Excel and DGL with or without melatonin treatment against chromium stress analyzed by using OJIP test (at different time scale) chromium treated and non-treated plants. Enhanced ROS scavenging antioxidants enzymes (SOD, POD, APX,CAT) and H2O2, MD Aactivity photo synthetic efficiency was observed against chromium stress. DGL cultivar showed greatly affected and showed maximum reduction in performing index of photosystem II and yield for primary photochemistry as compared to chromium treated and non-treated plants as compared to Ac-Excel. Performing index primarily comprises of active number of reaction centers as per absorption, primary photochemistry yield and efficiency of electron transfer in electron transport chain activities were observed high in Ac-Excel cultivar. However exogenous application of melatonin protected the oxygen evolving complex of PSII and helped out in maintaining PSII activity. Thus OJIP fluorescence transients are quite helpful for understanding the intersystem electron transport beyond photosystem II response of canola cultivars in chromium stress. Findings: Exogenous application of Melatonin can improve plant growth and development in heavy metalstress by modulation of photosynthesis in terms of enhanced photosystem II efficiency and redox potential in certain environmental stress conditions.

The purpose of conducting the study was to find the genetic components like Vg,Vp,GCV ,PCV ,heritability and Genetic advance in F2 generation of the cross Nagina x Bushbeef-steak for quantitative traits. Data was collected on P1, P2 F1 and F2 generation for various yield components and analyzed. Analyzed data showed relatively high difference between, GCV and Vp, PCV for the traits: Flowers/cluster, Fruits/cluster and Fruit weight and relatively low difference was noted for Vg, GCV and Vp, PCV value in the traits: Fruit diameter, Fruit length and fruits/plant. Highest value of GCV (79.90%) and PCV (92.79%) were noted in the trait: yield/plant and the lowest values of GCV (14.68%) and PCV (16.78%) were noted for fruit-length. Highest value (84.08%) of Broad sense heritability %(Hb%) was noted in fruit diameter and the lowest value of heritability(27.58) was noted for the trait fruits/cluster. Moderate value of heritability (74.13%) along with low value (15.22) of GA% was noted for yield/plant.

Cabbage white butterfly (Pieris brassicae) is one of the important insect pests of cabbage crop which causes remarkable quantitative or qualitative crop losses. The research was conducted at Hazara Agricultural research station, Abbottabad (Pakistan) to study the effect of different new chemical insecticides, botanical oil and neem seed oil (Azadirachta indica A. Juss.) on the population density of P. brassicae. The study showed that neem oil had a significant effect on population of P. brassicae in comparison to control treatment. So, neem oil alone or in combination with insecticides can be used for control of P. brassicae in vegetable crops for a safer food supply.