Toxicity of heavy-metals in soil is a major constraint for the production of carrots (Daucus carota L.). Different plant growth regulators are being used to overcome this problem. It has been found that plant growth regulators induce stress tolerance in plants. In this study, the role of exogenously applied plant growth regulator, gibberellic acid (GA₃) was examined in soil grown two carrot cultivars under four different levels of lead (0, 50, 100, and 150 mg/kg) with one level of gibberellic acid (50 ppm). Results showed that Pb stress retarded the plant growth and reduced chlorophyll contents in the leaves of both carrot cultivars. A significant decrease was observed in photosynthetic attributes by Pb addition alone. However, exogenously applied GA₃ ameliorated the plant growth and chlorophyll contents in the leaves of both carrot cultivars under Pb stressed conditions. Moreover, GA₃ also decreased the uptake of Pb concentration in carrot leaves and roots. In addition, GA₃ significantly regulated the phenolic compounds concentration in both carrot cultivars under Pb stress. In this study, cultivar T-29 was found to be more tolerant to Pb stress, however, cultivar Mevarick experienced higher damage regarding plant growth under Pb stress.

Carrot (Daucus carota L.) seed quality is affected by umbel position due to uneven maturation of carrot seeds produced in different umbel orders. However, keeping this in view, we tested whether seed quality could be improved with the suppression of tertiary umbels under exogenous auxin application. Using auxin-producing bacterial isolates, i.e., Bacillus sp. MN54, Enterobacter sp. MN17, Pantoea sp. MN34, and Burkholderia phytofirmans PsJN, the arrangements of carrot umbel order were evaluated in terms of quality carrot seed production. The results revealed that auxin production by plant-growth-promoting rhizobacteria showed significant differences among measured growth indices, yield, and seed quality attributes. The selected endophytic strains co-applied with auxin via foliar application improved all growth- and yield-related traits, as well as the enzymatic activities of carrots. Noticeably, MN17+L-tryptophan and MN34+L-tryptophan effectively minimized the number of tertiary umbels by increasing the number of secondary umbels. Furthermore, treating with PsJN+L-tryptophan and MN34+L-tryptophan resulted in reduced conductivity of seed leachates and malondialdehyde levels in primary, secondary, and tertiary umbel seeds. These findings collectively indicate the potential of the foliar application of PsJN+L-tryptophan and MN34+L-tryptophan to effectively alter umbel arrangement, leading to improved yield and seed quality. This study implies that carrot seed producers can consider employing specific PGPB strains, particularly MN34+L-tryptophan, to suppress tertiary umbels and achieve higher yields of high-quality carrot seeds.

Tri-genomic Brassica napus L.wasdeveloped by the cross between Brassica napusand Brassica nigra. The crop is animportant source of vegetable seed oil in Pakistan,after cotton. The low oilseed rape yield is attributed to high temperature in the production zones. Interspecific hybridization using these two speciescan be helpful to produce heat resistant hybrids. On the other hand, it has been found that foliar application of different plant growth regulators can be used to reduce the heat stress in Brassica. The objectiveof this studywas to test the response of three different tri-genomic hybrids to high temperature stressat seedling stage. Seedlings were foliar sprayed with 0.13 mM salicylic acid (SA) prior to exposure tohigh temperatureat two true leaf stage. The plants were harvested after 30 days of sowing for growth and biochemical analysis. Plants ofV38 showed the highest values for all morphological traits and biochemical activities among the threehybrids. In general, plants exposed to the temperature stress exhibited a significant decline in growth, chlorophyll content and enzyme activity.Foliar application of SA significantly improved leaf and root biomass under heat stress.Further, antioxidativeenzyme activities significantly increased in response to SA either compared to control or to plants exposed to temperature stress.It is concluded thatapplication of salicylic acid elevated activity of antioxidative enzymes and was helpful in mitigating the detrimental effects of high temperature inoil seed rape.

Onion (Allium cepa L.) is a biennial crop of high commercial value in Pakistan. Onion is considered as salt sensitive plant species. The present investigation was carried out to investigate the effect of salinity on onion and its alleviation through exogenously applied gibberellic acid (GA3; 100 mg L-1). Foliar application of GA3 (100 mg L-1) was applied on onion seedlings grown under three levels (0, 2 or 4 dS m-1) of salinity after 45 days of sowing. Results revealed that growth parameters and total soluble protein (TSP) contents declined with increase in soil salinity level. While, antioxidant enzyme activities (CAT, SOD and POD) were increased with salinity. However, exogenously applied GA3 significantly enhanced the plant growth and TSP in onion seedlings. Interestingly, CAT, SOD and POD concentration decreased with GA3 application which depicts stress alleviation in saline stressed onion plants due to GA3. It was concluded that the growth of onion could be enhanced to some extent by the application of GA3 under salinity stress.

Transplanting time and genotype contribute to improving crop yield and quality of eggplant (Solanum melongena L.). A field experiment was conducted to investigate the impact of foliar applied of triacontanol (TRIA) and eggplant genotypes 25919, Nirala, 28389 and Pak-10927,transplanted on 1 March,15 March, and 1 April on exposure to high air temperature conditions. The experiment was performed according to Randomized Complete Block Design and the data was analyzed by using Tuckey,s test . The TRIA was applied at 10µM at flowering stage; distilled water was used as the control. Rate of photosynthesis and transpiration, stomatal conductance, water use efficiency, and effects on antioxidative enzymes (superoxide dismutase, catalase and peroxidase) were evaluated. The 10µM TRIA increased photosynthesis rate and water use efficiency and yield was improved in all genotypes transplanted at the different dates. Foliar application of 10µM TRIA increased antioxidative enzyme activities (SOD, POD & CAT) and improved physiological as well as biochemical attributes of eggplant genotypes exposed to high heat conditions. Highest activity of dismutase enzyme 5.41mg/1g FW was recorded in Nirala genotype in second transplantation. Whereas, lowest was noted in PAK-10927 (2.30mg/g FW). Maximum fruit yield was found in accession 25919 (1.725kg per plant) at 1^st transplantation with Triacontanol, whereas accession PAK-10927 gave the lowest yield (0.285 kg per plant) at control treatment on 3^rd transplantation. Genotype, transplanting date and application of TRIA improved growth, yield and quality attributes under of heat stress in eggplant.

One of the vegetables, in which significant efforts are being done in the last years for interspecific breeding from related species for adaptation to climate change, is the common eggplant (Solanum melongena) (^{Liu et al., 2015}; ^{Plazas et al., 2016}). The eggplant belongs to the Solanaceae family, which is a highly valuable horticultural crop grown all over the world and it is of substantial economic importance in Asia, Africa, and the subtropics (^{Collonnier et al., 2001}). It is a good source of proteins, minerals, and antioxidant and also has medicinal value (^{Magioli & Mansur, 2005}). However, its production is severely threatened by several soil-borne and foliar diseases, insect-pests, drought, heat and frost damage, which reduce yield (^{Collonnier et al., 2001}). Therefore, efforts to transfer useful resistance genes into eggplant from the wild relatives are important because of the lack of resistance in common eggplant gene pool.