This study aimed to adopt the concept of 4R nutrient stewardship for growing off-season tomatoes in high tunnels. The tomato crop (Hybrid 'Sahel'), grown in high tunnels, was applied with NPK fertilizer at the rate of 80:80:90 kg ha -1 (after each 15, 30 and 45 days interval) for four months and its effect on tomato yield and quality parameters was investigated. Application of NPK at 15 day intervals resulted in the highest nutritional quality of fruit (NPK uptake 4.32 kg m -2 , total soluble solids 5.6°Brix, total acidity 0.43%, protein content 15.31%, β-carotenes 0.86 mg 100 g -1 , total phenolics 2.34 mg 100 g -1 , total flavonoids 7.14 mg 100 g −1 , antioxidant activity 83.77%) and improved shelf-life (~ 10 days). However, NPK application at 15 day intervals was not economical in terms of total fertilizer cost incurred and subsequent yield obtained. Application of NPK at 30 day intervals was the most economical (value-cost ratio > 9.0 PKR) among all application intervals. This study suggested that implementation of the concept of 4Rs i.e., right source, right rate, right placement and right timing of fertilizer application is an effective tool for the production of high quality off-season tomatoes in high tunnels.

A flatoxins represent a major class of mycotoxin that are highly toxic and carcinogenic in nature. They are mostly produced by closely related species of Aspergillus in many agricultural products worldwide (Pickova et al., 2021). The B-group aflatoxins i.e., AFB 1 and AFB 2 are typically produced by Aspergillus flavus, while most toxigenic strains of Aspergillus parasiticus have great potential in producing all the four kinds i.e., AFB 1 , AFB 2 , AFG 1 and AFG 2 of aflatoxins (Dorner, 2004). Aflatoxins are chemical derivatives of difuranocoumarin formed by fusion of two furans and one coumarin ring synthesized by polyketide pathway. Aflatoxins are classified into more than eighteen different types among which AFB1, AFB2, AFG1, AFG2, AFM1 and AFM2 are the most important and naturally occurring members found in different food commodities (Benkerroum, 2020). Many species in section Flavi also produce Abstract | This study aimed to characterize different Aspergillus section Flavi isolates in search for nonaflatoxigenic strains for use as biocontrol agent. A total of 434 isolates of A. flavus were isolated from soil and stored maize grain samples collected from four agroecological zones (AEZ) i.e., AEZ-A, AEZ-B, AEZ-C and AEZ-D of Khyber Pakhtunkhwa (KP) province of Pakistan. The mycological analysis of the samples demonstrated that the highest population of Aspergillus section Flavi was existed in soil (n = 236) than in maize grain samples (n = 198). Across all the four zones, the highest population of Aspergillus section Flavi was observed in AEZ-C (n = 115) whereas the lowest population was found in AEZ-B (n= 99). The isolates of Aspergillus section Flavi were then characterized for their aflatoxigenicity and nonaflatoxigenicity by cultural (i.e., production of blue fluorescence, room temperature phosphorescence, ammonium hydroxide vapor induced color change and sclerotia production) and immunological methods i.e., enzyme linked immunosorbent assay (ELISA). All the four cultural methods successfully differentiated aflatoxigenic and nonaflatoxigenic isolates, however ammonium hydroxide vapor induced test was found to be the most efficient (80.29%) for segregation of the isolates. Among all isolates, thirty were screened for their total aflatoxin production in corn meal agar medium by using ELISA technique. The results showed that isolate AFS32 produced highest level of total aflatoxin (230.78 µg Kg -1 ) while isolates AFS5, AFS17, AFS25 and AFS33 produced no aflatoxin. These nonaflatoxigenic isolates were considered as isolates of interest and could be used as biocontrol agent in agricultural fields for prevention of pre-harvest aflatoxins production in different crops.