In response to shading, plant leaves acclimate through a range of morphological, physiological and biochemical changes. Plants produce a myriad of structurally and functionally diverse metabolites that play many important roles in plant response to continually changing environmental conditions as well as abiotic and biotic stresses. To develop a clearer understanding of the effects of shade on soybeans at different growth stages, a comprehensive, three-year, stage-wise study was conducted. Leaf area, leaf thickness, stem diameter, chlorophyll contents, photosynthetic characteristics and other morphological and physiological features were measured along with biochemical assays for antioxidants such as superoxide dismutase, peroxidase and caralase and yield attributes of different soybean genotypes (Guixia 2, Nandou12, Nandong Kang-22, E61 and C103) under shading nets with 50% light transmittance. It was observed that early shading (VER1 and VER2) significantly decreased main stem length and main stem length/stem diameter. Later shading (R1R8 and R2R8) had significant effects on morphological characters such as branch number and pod height. In Nandou 12, the protein contents in plants shaded at R1R8, R2R8 and R5R8 were 9.20, 8.98 and 6.23% higher than in plants grown under normal light levels (CK), respectively, and the crude fat content was 9.31, 10.74 and 4.28% lower. The influence of shading in the later period on anatomy was greater than that in the earlier period. Shading reduced the light saturation point (LSP), the light compensation point (LCP) and the maximum photosynthetic rate (Pnmax), and increased the apparent quantum yield (AQ). Shading also increased the antioxidant enzyme activity in the plants, and this increase was greater with early shading than late. The variability in the chlorophyll (a + b) content and the chlorophyll a/b ratio in R2 stage plants was less than in R5 stage (VER5) plants. Similarly, the activity of antioxidant enzymes in R2 after returning the plants to normal light levels (VER2) was lower than in R5 after relighting (VER5). Compared with later shading, the early shading had a greater effect on the photosynthetic and related characteristics. The longer the shading time, the greater the adverse effects and the less able the plants’ were to recover. The data collected in this study contribute to an understanding of the physiological mechanisms underlying the early and late growth stage acclimation strategies in different soybean genotypes subjected to shade stress.

Oilseed crops require several micronutrients to support their physiological functions and reproductive phases. A deficiency of these nutrients can significantly reduce the yield and oil quality of oilseed crops. Soil application of micronutrients can reduce their deficiency and improve plant growth, yield, and oil quality. Oilseed rape (Brassica napus L.) is an important oilseed crop that produces oil with low levels of saturated fat and high levels of beneficial omega-3 fatty acids, which renders it a widely used cooking oil. However, the yield and oil quality of oilseed rape are significantly affected by the deficiency of boron (B) and zinc (Zn). This two-year field study determined the influence of sole and combined soil application of B and Zn on the physiological attributes of plants, seed and oil yields, and oil quality under semiarid climatic conditions. Nine different B and Z combinations, i.e., B0 + Zn0 (control), B0 + Zn8, B0 + Zn10, B1 + Zn0, B1 + Zn8, B1 + Zn10, B2 + Zn0, B2 + Zn8, and B2 + Zn10 (kg ha⁻¹), were included in the study. Sole and combined application of B and Zn significantly altered physiological attributes, seed and oil yields, and oil quality. The highest values for plant height, number of siliques per plant, number of seeds per silique, 1000-seed weight, seed and oil yields, oil quality (higher stearic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid, and lower erucic acid), and physiological traits (protein concentration, soluble sugar concentration, chlorophyll concentration, photosynthesis and transpiration rates, and stomatal conductance) were recorded with the combined application of 2 + 8 kg ha⁻¹ B and Zn, respectively, during both years of this study. The lowest values of yield- and oil-quality-related traits and physiological attributes were recorded for the control treatment. A dose-dependent improvement was recorded in B and Zn contents in leaves, and the highest values were recorded with the combined soil application of 2 + 10 kg ha⁻¹ B + Zn, respectively. It can be concluded that 2 + 8 kg ha⁻¹ B + Zn should be applied to oilseed rape for higher seed and oil yields and better oil quality under semiarid climatic conditions.

Background: Waste-land weeds present around the fields exert their allelopathic influence on crops through their leaf leachates and rhizospheric soils. Objective: A study was conducted to investigate the phytotoxic action of four common waste-land weeds Parthenium hysterophorus L., Achyranthes aspera L., Lantana camara L. and Withania somnifera L. through their aqueous extracts and rhizospheric soils against winter crops Avena sativa L., Cicer arietinum L., Hordeum vulgare L. and Triticum aestivum L. Methods: Experiments were conducted in Agronomy laboratory in College of Agriculture at the University of Sargodha. In first experiment, 5% (w/v) water extract from entire plant of each weed was applied to germinating seeds of crops whereas in second experiment, crop seeds were subjected to the rhizospheric soil of each weed for germination test. Results: Results revealed that aqueous extracts of weeds were more phyto-inhibitory compared to their rhizospheric soils. Minimum germination percentage (42.5%), germination index (7.4), seedling vigor index (665.3), root length (3.27 cm), seedling length (14.15 cm) and seedling biomass (74.2 mg) of crops were recorded in response to aqueous extract of P. hysterophorus. Root growth of the crops was affected more compared to the shoot growth. Minimum germination percentage was observed in A. sativa (13.3) by the action of L. camara aqueous extract. Rhizospheric soil of L. camara and P. hysterophorus resulted in minimum germination percentages (57.5 and 58.3, respectively) and seedling vigor indices (1472.5 and 2008.4, respectively) of crops. The lowest germination (30%) and germination index (3.7) was observed for T. aestivum seeds germinated in the rhizospheric soil of W. somnifera. Among crops, A. sativa and C. arietinum were more susceptible to the aqueous extracts whereas T. aestivum to rhizospheric soils of weeds. Conclusions: It can be concluded that waste-land weeds especially P. hysterophorus and L. camara negatively affect the crops by their allelopathy.

Biosynthesis and subsequent release of allelochemicals by a plant into the environment is supposed to be influenced by its growing conditions. To ascertain what will be the allelopathic action of plant parts and rhizospheric soils of parthenium (Parthenium hysterophorus) growing at various farm locations with varied growing conditions, germination and seedling growth of maize hybrid (DK 6142) were assayed by sowing its seeds in petri plates lined with filter paper and pots filled with soil. Minimum germination percentage (30.0%), germination index (2.01), germination energy (36.3), seedling length (3.3 cm), seedling biomass (10 mg) and seedling vigor index (99.0) of maize were observed in leaf extract followed by fruit and whole plant extracts of parthenium growing near the field border. Rhizospheric soil collected underneath parthenium growing near a water channel caused maximum reductions in germination index (30.8%), germination energy (40.6%), seedling length (32.6%), seedling biomass (35.1%) and seedling vigor index (34.3%) of maize compared with that soil without any vegetation. Phytotoxic inhibitory effects of both parthenium plant and rhizospheric soil were more pronounced on maize root than its shoot growth. The higher suppressive action against germination and seedling growth of maize was probably due to higher total phenolic concentrations (6678.2 and 2549.0 mg L-1) and presence of phenolic compounds viz., gallic, caffeic, 4-hydroxy-3-methoxy benzoic, p-coumaric and m-coumaric acids; and ferulic, vanillic, syringic and m-coumaric acids in aqueous leaf extract of parthenium uprooted near the field border and its rhizospheric soil collected near a water channel, respectively.

Background: Thermal weed control is a viable, cost-effective, and eco-friendly emerging alternative to highly challenged and unsustainable chemical weed control. Objective: To find out the most suitable pre-sowing soil solarization durations for effective weed control and soil fertility enhancement in sesame crop. Methods: A field study was conducted during the summer season of 2016 and 2017. Different soil solarization treatments were applied, including 0, 3, 6, 9, and 12 weeks before sowing (WBS) of sesame by spreading transparent polythene [...] Abstract Background: Thermal weed control is a viable, cost-effective, and eco-friendly emerging alternative to highly challenged and unsustainable chemical weed control. Objective: To find out the most suitable pre-sowing soil solarization durations for effective weed control and soil fertility enhancement in sesame crop. Methods: A field study was conducted during the summer season of 2016 and 2017. Different soil solarization treatments were applied, including 0, 3, 6, 9, and 12 weeks before sowing (WBS) of sesame by spreading transparent polythene