M. A. Cheema

Alternative control of wild oat and canary grass in wheat fields by allelopathic plant water extracts

The increasing concern about the toxicity of synthetic herbicides has boosted the search for eco-friendly and sustainable weed management practices. Allelopathic control of weeds has received great attention in recent years as a possible alternative for weed management. Here, a two-year field study was conducted to explore the herbicidal potential of sorghum water extract alone and in combination with water extracts of other allelopathic plants: eucalyptus, sesame, sunflower, tobacco and brassica, against wild oat (Avena fatua) and canary grass (Phalaris minor), two noxious weeds of wheat fields. Water extracts were applied twice 30 and 40 days after sowing. Our results show that application of sorghum and sunflower extracts at 12 L ha−1 each was more effective than other combinations. This treatment reduced wild oat dry matter by 42–62%, and canary grass by 36–55%. Application of sorghum and sunflower at 6 L ha−1 each increased the wheat grain yield by 89% during the first year, and by 35% during the second year. Application of the synthetic herbicide isoproturon at 1000 g active ingredient ha−1 was more effective for weed inhibition and yield increase than allelopathic water extracts. Nevertheless, application of sorghum and sunflower at 6 L ha−1 was economically more viable than the other treatments, with the highest marginal rate of return of 2824%.

Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources

Sharifi, M., Cheema, M., Mahoney, K., LeBlanc, L. and Fillmore, S. 2013. Evaluation of liming properties and potassium bioavailability of three Atlantic Canada wood ash sources. Can. J. Plant Sci. 93: 1209-1216. Wood ash has the potential to enhance productivity in agricultural systems by influencing soil pH and nutrient availability. The liming properties and fertility values of wood ash from three Atlantic wood ash sources were evaluated in this study. The liming properties were tested using three wood ash sources [JD Irving (IR), New Page (NP), and Brooklyn Power (BP)] and two local lime sources in an 8-mo incubation experiment at 25°C. Soil pH was measured 14 times during the incubation. Availability of potassium (K) in wood ash was evaluated in a greenhouse setting with a K-deficient soil using annual ryegrass as the test plant. Total plant K and P uptake and Mehlich-3 extractable K and P were used as predictors of nutrient bioavailability. Wood ash application increased soil pH to the maximum level within the first 50 d after application and stabilized soil pH for 8 mo. The measured effective calcium carbonate equivalent of ashes relative to Mosher lime average among two soils were in order of BP (32)>IR (25)>NP (16). About 96, 38, and 71% of total K in IR, NP and BP ash sources, respectively, were bioavailable for ryegrass in 115 d. Although soil was not P deficient, soil P bioavailability (Mehlich III extractable P) was enhanced by 14 and 48% in NP and BP wood ash treatments, respectively, whereas P bioavailability decreased by 24% in the IR ash treatment. The results clearly demonstrate that these sources of wood ash can be considered as an effective liming agent and source of K in agricultural production systems.

Yield and quality response of autumn-planted sunflower (Helianthus annuus L.) to sowing dates and planting patterns

Sowing time and sowing methods are often used to overcome environmental constraints on crop production. Information on the effect of these agronomic techniques on sunflower (Helianthus annuus L.) oil quality is, however, scarce. A field study was conducted to evaluate the effect of sowing dates and planting patterns, and their interaction, on seed yield and oil quality of hybrid sunflower. Sunflower hybrid Hysun-33 was sown at four dates beginning with the first week of August with fortnightly intervals under three planting patterns, viz., flat sowing (60 cm apart lines), ridge sowing (60 cm apart ridges) and bed sowing (90/30 cm) for 2 yr (2002 and 2003). The performance of the August sowing dates was significantly better with respect to yield and yield components than the September-sown crop. Among the three sowing dates in August, there was variable performance of the crop in the 2-yr study. On average, the sowing of sunflower from mid-August to the last week of August yielded better than early August ...

Enhancement of Antioxidant Defense System Induced by Hormonal Priming in Wheat

Use of plant hormones as seed priming agents is known to improve the field performance especially under stressful conditions like salinity. A pot experiment was conducted to study the effects of seed priming of two wheat (Triticum aestivum L.) cultivars Auqab-2000 (salt tolerant) and MH-97 (salt sensitive) under saline (15 dS m−1) and non-saline (2.75 dS m−1) conditions. For priming seeds were soaked in aerated water (hydropriming), and solutions of kinetin (Kin; 25 mg L−1), or salicylic acid (SA; 50 mg L−1) for 12 h. All the priming treatments significantly reduced the adverse effects of salinity in terms of improving final emergence, growth and grain yield of both cultivars. Seed priming with SA and Kin improved salt tolerance in both wheat cultivars by the activation of antioxidants, i.e. superoxide dismutase (SOD) and catalase (CAT) to counterbalance the oxidative damage. Albeit, Na+ and Cl− contents increased due to salinity, all priming strategies lowered the accumulation of Na+ and enhanced the acc...

Separate and combined effects of silicon and selenium on salt tolerance of wheat plants

Soil salinity is the leading global abiotic stress which limits agricultural production with an annual increment of 10%. Therefore; a pot experiment was conducted with the aim to alleviate the salinity effects on wheat seedlings through exogenous application of silicon (Si) and selenium (Se). Treatments included in the study were viz. (Ck) control (no NaCl nor Si and Se added), only salinity (50 mM NaCl), salinity + Si (50 mM NaCl with 40 mM Si), salinity + Se (50 mM NaCl with 40 mM Se) and salinity + Si + Se (50 mM NaCl + 40 mM Si + 40 mM Si). The salt stress impaired the growth (root and shoot dry weight, root: shoot ratio, seedlings biomass), water relations, photosynthetic attributes, transpiration rate and chlorophyll contents of wheat seedlings. Nonetheless, the foliar application of Si and Se alone and in combination improved the growth, water relations, photosynthetic attributes, transpiration rate and chlorophyll contents of wheat seedlings under stressed conditions. Moreover, an increase in antioxidant enzyme activity and accumulation of osmo-protectants (proline, soluble protein and soluble sugar) was noted under stressed conditions, which was more pronounced in wheat seedling which experienced combined application of Si and Se. To conclude that, foliar application of Si alone mitigated the adverse effect of salinity, while the combined application of Si and Se was proved to be even more effective in alleviating the toxic effects of salinity stress on wheat seedlings.

THE Cd:Zn RATIO IN A SOIL AFFECTS Cd TOXICITY IN SPINACH (Spinacea oleracea L.)

The current population of Pakistan is almost 192 million (Economic Survey of Pakistan, 2014-15) and the water requirements for drinking and agronomic purposes are almost solely fulfilled from a single river system. The River Indus and its tributaries irrigate nearly all of the arable soils of the arid and semi-arid areas of the Pakistan. However, poor systems of irrigation distribution, a rapidly growing population, recurrent droughts and saline groundwater have all resulted in increased water shortages. Thus Pakistan has a significant water deficit issue owing to the lack of available surface storage reservoirs and ongoing depletion of ground water resources (Kashif et al., 2009). Thus due to the scarcity of fresh water supplies, today untreated waste water is more frequently used for irrigation. However, untreated waste water may contain number of potential contaminants including heavy metals, inorganic salts, organics and pathogens (Qadir et al., 2010). Continuous use of wastewater is bringing the high concentrations of Cd and elevating its level in the agricultural soil of Pakistan. Cadmium is released in soil environment through different anthropogenic activities such as atmospheric deposition, application of phosphatic fertilizers, pesticides, cement industries and metal industries (Lim et al., 2013; Lee et al., 2013). In particular, the high mobility of heavy metals is a major concern because of the potential for this to result in food chain contamination. Cadmium which exhibits very high mobility compared to other metals such as Pb, has the greatest potential to enter food chain in relatively high concentrations (Khodaverdiloo et al., 2011). Mobile Cd mainly accumulates in aerial plant parts and is transferred to animals and humans when they consume the edible parts of the food crop, especially the leaves of leafy vegetables. Excessive Cd intake is also a major concern because Cd accumulates in the body over time (McLaughlin et al., 1999; Kabir et al., 2014). The contamination of vegetables by heavy metals; especially leafy vegetables like spinach (Spinacea oleracea L.) is a serious issue because of the significance of vegetables as food commodity and as a primary source of proteins, vitamins, iron, calcium and other essential minerals. The concentration of these metals in the edible parts of leafy vegetables depends mainly on the magnitude of soil contamination and the soil quality. Whereas, the innate ability of the plant to tolerate exposure to heavy metals together with the degree of soil contamination determine the overall tolerance of the plant to soil heavy metals (Sikka and Nayyar, 2012). Spinach has a relatively high potential to accumulate heavy metals such as Cd and Pb in its leaves and thus high potential to cause adverse human health effects when these leaves are consumed (Chunilall et al., 2004; Intawongse and Dean, 2006). High metal uptake commonly exhibited by spinach may be related to its physical structure. As broad leafy vegetable spinach has a large surface area which allows for both a high rate of transpiration and also a large surface area for the absorption of heavy metals. Pak. J. Agri. Sci., Vol. 53(2), 419-424; 2016 ISSN (Print) 0552-9034, ISSN (Online) 2076-0906 DOI: 10.21162/PAKJAS/16.5216 http://www.pakjas.com.pk

The use of natural media amendments to produce kale enhanced with functional lipids in controlled environment production system

Diets high in vegetable consumption is highly correlated with reduced risk of developing common lifestyle related diseases. We investigated the effects of three natural growth media amendments [potassium humate, dry vermicast, volcanic minerals or Promix alone (Control)] in enhancing the accumulation of functional lipids in greenhouse grown kale. Functional lipids (n9, n6, n3 fatty acids, diglycerides, galactolipids and phytosterols) were assessed using either gas chromatography/mass spectrometry (GC/MS) or ultra-high performance liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS). The results showed volcanic minerals and dry vermicast were the most successful in enhancing the accumulation of functional lipids in kale. For example, dry vermicast enhanced the accumulation of total C18:1n9 and C16:3n3 fatty acids, while total C18:2n6 fatty acid accumulation was enhanced by volcanic minerals. In conclusion, natural growing medium amendments are remarkably effective in modulating the accumulation of functional lipids in kale grown under controlled-environment conditions. This could be a useful strategy for functional foods production in control environment production systems. Increase access to kale with enhanced functional lipids could aid in increase consumption of these health promotive compounds in the diet with potential implications in population health.

Physiological response of late sown wheat to exogenous application of silicon

Late planting of wheat in rice-wheat cropping system is perhaps one of the major factors responsible for low crop yield. The main cause of reduction in yield is due to supra-optimal conditions during the reproductive growth. High temperature during reproductive phase induces changes in water relations, decreases photosynthetic rate, and transpiration rate, stomatal conductance and antioxidative defence system. Silicon (Si), being a beneficial nutrient not only provides significant benefits to plants growth and development but may also mitigate the adversities of high temperature. A field study was conducted at Agronomic Research Area of University of Agriculture; Faisalabad, Pakistan to assess the performance of late sown wheat with the soil applied Si. Experiment was comprised of three sowing dates; 10th Nov (normal), 10th Dec (late), 10th Jan (very late) with two wheat varieties (Sehar-2006 and Faisalabad-2008), and an optimized dose of Si (100 mg per kg soil), applied at different growth stages (control, crown root, booting and heading). Results indicated that 100 mg Si per kg soil at heading stage offset the negative impact of high temperature and induced heat tolerance in late sown wheat. Silicon application improved 34% relative water contents (RWC), 30% water potential, 26% osmotic potential, 23% turgor potential and 21% photosynthetic rate, and 32% transpiration rate and 20% stomatal conductance in wheat flag leaf than control treatment. Further it was observed that Si application preventing the oxidative membrane damage due to enhanced activity of antioxidant enzymes, i.e. 35% superoxide dismutase (SOD) and 38% catalase (CAT). In conclusion results of this field study demonstrated that soil applied Si (100 mg per kg soil) at heading stage enhanced all physiological attributes of wheat flag leaf. Which in turn ameliorated the adverse effects of high temperature in late sown wheat. Study depicted that Si can be used as a potential nutrient in order to mitigate the losses induced by high temperature stress.

Effect of fungicide combinations for Fusarium head blight control on disease incidence, grain yield, and quality of winter wheat, spring wheat, and barley

Abstract: This study investigates the effects of timing of fungicide applications alone or in combinations on Fusarium head blight (FHB), seed deoxynivalenol (DON) concentrations, dominant leaf diseases, grain yield, and thousand-kernel weight in winter wheat, spring wheat, and barley in the Atlantic region of Canada. The experiments were conducted for 3 yr (2010–2012), with fungicide treatment as the main factor. Selected commercially available fungicide treatments were applied at two timings: (i) Zadoks growth stage (ZGS) 39: check, propiconazole + trifloxystrobin (125 g ha-1), propiconazole (125 g ha-1), and pyraclostrobin (100 g ha-1); and (ii) ZGS 60: check, prothioconazole (200 g ha-1), prothioconazole + tebuconazole (200 g ha-1), and metaconazole (90 g ha-1). Results show that a single fungicide application was not sufficient to achieve a high yield with good seed quality. Reduction of visual FHB infection due to fungicide applications did not guarantee a reduction in seed DON concentrations. Fungicide application pyraclostrobin at ZGS 39 and prothioconazole + tebuconazole at ZGS 60 was the best treatment, consistently providing the highest crop yield and seed quality, including lowered DON.

Boron fertilization improves seed yield and harvest index of Camelina sativa L. by affecting source-sink

ABSTRACT The impact of soil (1, 2 kg ha−1) and foliar (100, 200 mg L−1) boron (B) with control (no B) was evaluated on phenology and yield formation of Camelina each applied at stem elongation and flowering stages. Foliar (200 mg L−1) or soil B (2 kg ha−1) resulted in earlier flowering and maturity, increased fruit bearing branches (19.68%), number of siliqua, seeds per siliqua (4.6%), biological yield (15%), seed yield (24%), harvest index (11.4%) and oil contents (23%) than no B. Increased fruit bearing branches, seed filled siliqua or seed numbers, harvest index and oil quality can be attributed to changes in dry matter accumulated of stem with simultaneous increase in siliqua dry weight with foliar or soil applied B. In crux, foliar (200 mg L−1) or soil applied (2 kg ha−1) B seems promising to improve seed and oil yield, harvest index of Camelina sativa under B deficient condition.