Molasses-based waste water irrigation: a friend or foe for carrot (Daucus carota L.) growth, yield and nutritional quality.

Management of molasses-based wastewater generated in yeast and sugar industries is a major environmental concern due to its high chemical oxygen demand and other recalcitrant substances. Several strategies have been used to reduce the inland discharge of wastewater but the results are not satisfactory due to high operating cost. However, reuse of molasses-based wastewater irrigation in agriculture has been a major interest nowadays to reduce the freshwater consumption. Thus, it is crucial to monitor the impacts of molasses-based waste water irrigation on growth, metabolism, yield and nutritional quality of crops for safer consumer's health. In present study, carrot seeds of a local cultivar (T-29) were germinated on filter paper in Petri dishes under controlled conditions. The germinated seeds were then transplanted into pots and irrigated with three different treatments normal water (T0), diluted molasses-based wastewater (T1), and untreated molasses-based wastewater (T2), in six replicates. Results revealed that carrot irrigated with untreated molasses-based waste water had exhibited significant reductions in growth, yield, physiology, metabolism, and nutritional contents. Additionally, accumulation of Cd and Pb contents in carrot roots irrigated with untreated molasses-based waste water exceed the permissible limits suggested by WHO and their consumption may cause health risks. While, diluted molasses-based waste water irrigation positively enhanced the growth, yield of carrot plants without affecting the nutritional quality. This strategy is cost effective, appeared as most appropriate alternative mean to reduce the freshwater consumption in water deficit regions of the world.

Seed priming with potassium nitrate alleviates the high temperature stress by modulating growth and antioxidant potential in carrot seeds and seedlings.

Early season carrot (Daucus carota) production is being practiced in Punjab, Pakistan to meet the market demand but high temperature hampers the seed germination and seedling establishment which cause marked yield reduction. Seed priming with potassium nitrate breaks the seed dormancy and improves the seed germination and seedling growth potential but effects vary among the species and ecological conditions. The mechanism of KNO3 priming in high temperature stress tolerance is poorly understood yet. Thus, present study aimed to evaluate high temperature stress tolerance potential of carrot seeds primed with potassium nitrate and impacts on growth, physiological, and antioxidant defense systems. Carrot seeds of a local cultivar (T-29) were primed with various concentration of KNO3 (T0: unprimed (negative control), T1: hydroprimed (positive control), T2: 50 mM, T3:100mM, T4: 150 mM, T5: 200 mM, T6: 250 mM and T7: 300 mM) for 12 h each in darkness at 20 ± 2℃. Seed priming with 50 mM of KNO3 significantly enhanced the seed germination (36%), seedling growth (28%) with maximum seedling vigor (55%) and also exhibited 16.75% more carrot root biomass under high temperature stress as compared to respective control. Moreover, enzymatic activities including peroxidase, catalase, superoxidase dismutase, total phenolic contents, total antioxidants contents and physiological responses of plants were also improved in response to seed priming under high temperature stress. By increasing the level of KNO3, seed germination, growth and root biomass were reduced. These findings suggest that seed priming with 50 mM of KNO3 can be an effective strategy to improve germination, growth and yield of carrot cultivar (T-29) under high temperature stress in early cropping. This study also proposes that KNO3 may induces the stress memory by heritable modulations in chromosomal structure and methylation and acetylation of histones that may upregulate the hormonal and antioxidant activities to enhance the stress tolerance in plants.

Proximate composition and prevalence and exposure assessment of aflatoxins intake through consumption of fresh carrot and processed marketed carrot products in South Punjab, Pakistan.

Carrot (Daucus carota L.) is a nutrient-rich vegetable that is widely cultivated and consumed in Pakistan in both raw and processed form. Data on the proximate composition and natural occurrence of aflatoxins (AFs) in carrots and marketed carrot products is lacking in Pakistan and the risk exposure of AF has not been characterised before. Thus, the current study was designed to know the frequently consumed carrot products with per capita consumption, and risk assessment of AF through these products in various regions of South Punjab Pakistan. A survey was conducted with 125 respondents and appeared that raw carrot, fresh carrot juice, gajrella and pickle are the most frequently consumed marketed carrot products with per capita consumption i.e. 62.5, 46.6, 16.2 and 14.5 gday-1, respectively. Proximate analysis revealed that carrot root and processed carrot products contained 9.65-98.2% moisture, 0.23-0.60% ash, 6.2-14.1% carbohydrates, 0.31-0.80% protein, 0.40-3.7% fat and 1.4-4.20% fibre. AF analysis revealed that 36.67% of samples were contaminated with TAF. Thirty-five (35%) percent of samples were tainted with aflatoxin B1, and 13.33% of samples were contaminated with aflatoxin B2. All the samples of carrot root, fresh carrot juice and gajrella contained TAF levels less than the maximum limit (ML) (2 ppb) assigned by the European Union (EU). However, the entire AFB1 positive samples of carrot pickle contained AFB1 levels of more than 2 ppb exceeding the ML. Furthermore, daily dietary exposure of TAFs ranged from 0.11 to 1.27 ng/kg of body weight per day which relatively exceeds the permissible limit of 1 ng/kg of body weight per day as defined by the Joint FAO/WHO Expert Committee on Food Additives. This is the first prevalence and risk assessment report of AF in marketed processed carrot products in Pakistan. These baseline data are an initial step in the effort to deal with this significant food safety issue and the establishment of legislation for AF in marketed products is needed in Pakistan.