Selection and characterization of wheat genotypes for saline soils prone to water‐logging

Wheat (Tritcum aestivum L.) genotypes were screened and characterized for performance under salt stress and/or water‐logging. In a solution‐culture study, ten wheat genotypes were tested under control, 200 mM–NaCl salt stress and 4‐week water‐logging (nonaerated solution stagnated with 0.1% agar), alone or in combination. Shoot and root growth of the wheat genotypes was reduced by salinity and salinity × water‐logging, which was associated with increased leaf Na⁺ and Cl^– concentrations as well as decreased leaf K⁺ concentration and K⁺ : Na⁺ ratio. The genotypes differed significantly for their growth and leaf ionic composition. The genotypes Aqaab and MH‐97 were selected as salinity×water‐logging‐resistant and sensitive wheat genotypes, respectively, on the basis of their shoot fresh weights in the salinity × water‐logging treatment relative to control. In a soil experiment, the effect of water‐logging was tested for these two genotypes under nonsaline (EC = 2.6 dS m^–1) and saline (EC = 15 dS m^–1) soil conditions. The water‐logging was imposed for a period of 21 d at various growth stages, i.e., tillering, stem elongation, booting, and grain filling alone or in combinations. The maximum reduction in grain yield was observed after water‐logging at stem‐elongation + grain‐filling stages followed by water‐logging at grain‐filling stage, booting stage, and stem‐elongation stage, respectively. Salinity intensified the effect of water‐logging at all the growth stages. It is concluded that the existing genetic variation in wheat for salinity × water‐logging resistance can be successfully explored using relative shoot fresh weight as a selection criterion in nonaerated 0.1% agar–containing nutrient solution and that irrigation in the field should be scheduled to avoid temporary water‐logging at the sensitive stages of wheat growth.     

Use of optical spectrograpiuc 15N-analyses to trace nitrogen applied at tile heading stage of rice

In the recent decades experimental work has led to the accumulation of vast quantities of valuable data on mineral nutrition of plants through the use of isotopic tracers. However, only limited research has been done with nitrogen presumably because of the high costs of instrumentation and isotopes. A few Investlgatlons on the distribution and accumulation of nitrogen have been reported using mass spectrographic method. For example, Ozaki et al. (1) observed a larger distribution of ammonical nitrogen administered before heading, Into ears, culms, and boot leaves in contrast with other plant parts. They further noted that 35% of the nitrogen applied after heading was found in the ears (2).     

The uptake,distribution, and accumulation of 15N-labelled ammonium and nitrate nitrogen top-dressed at different growth stages of rice

A pot experiment with soil culture was carried out to trace ¹⁵N-labelled nitrogen top-dressed at different growth stages of rice. The study involves the use of a modified vacuum system for determining total nitrogen by gu volumetric measurement, and the N₂ gas sampled in the discharge tube was analysed for nitrogen-15 by the optical spectrographic technique.

The plants took up more nitrogen from (¹⁵NH₄)₂SO₄ than from Na¹⁵NO₃, irrespective of the stage of dressing, and the uptake of both forms was much higher when the planta were top-dressed at the young panicle formation stage as compared with the later dressings. At full maturity the plants had the highest accumulation of labelled nitrogen from both ammonium and nitrate sources when they are top-dressed at the young panicle formation stage. More than 80% ot the labelled nitrogen taken up by the plants waa distributed in the brown rice and this trend was more remarkable when top-dressing was carried out at the milk stage. The distribution patterns of ammonium and nitrate nitrogen were similar in brown rice but differed in leaves and stem.

Nitrogen transported from other parts to the panicle was utilized for the formation ot the husk until the booting stage, and then for brown rice development. With the completeness of husk formation, at the milk stage, nitrogen transported to the grain might have been utilized for brown rice development more rapidly. In the brown rice, nitrogen from ammonium was translocated maximally to the inner part of the endosperm from dressing at the booting stage, and to the embryo from that at the milk stage, whereas that from nitrate was translocated maximally to the embryo from the dressings at both stages.     

Alleviation of manganese toxicity and manganese-induced iron deficiency in barley by additional potassium supply in nutrient solution

Barley plants were grown hydroponically at two levels of K (3.0 and 30 mm) and Fe (1.0 and 10 μm) in the presence of excess Mn (25 μm) for 14 d in a phytotron. Plants grown under adequate K level (3.0 mm) were characterized by brown spots on old leaves, desiccation of old leaves, interveinal chlorosis on young leaves, browning of roots, and release of phytosiderophores (PS) from roots. These symptoms were more pronounced in the plants grown under suboptimal Fe level (1.0 p,M) than in the plants grown under adequate Fe level (10 μm). Plants grown in 10 μm Fe with additional K (30 mm) produced a larger amount of dry matter and released less PS than the plants grown under adequate K level (3.0 mm), and did not show leaf injury symptoms and root browning. On the other hand, the additional K supply in the presence of 1.0 μM Fe decreased the severity of brown spots, prevented leaf desiccation, and increased the leaf chlorophyll content, which was not sufficient for the regreening of chlorotic leaves. These results suggested that the additional K alleviated the symptoms of Mn toxicity depending on the Fe concentration in the nutrient solution. The concentration (per g dry matter) and accumulation (per plant) of Mn in shoots and roots of plants grown in 10 μm Fe and 30 mm K were much lower than those of the plants grown in 10 μm Fe and 3.0 mm K, indicating that additional K repressed the absorption of Mn. The concentration and accumulation of Fe in the shoots and roots of the plants grown in 10 μm Fe and 30 mm K were higher than those of the plants grown in 10 μm Fe and 3.0 mm K, indicating that the additional K increased the absorption of Fe under excess Mn level in the nutrient solution. The release of PS, chlorophyll content, and shoot Fe concentration were closely correlated.     

ROOT ZONE TEMPERATURE INFLUENCES ZINC REQUIREMENT OF MAIZE CULTIVARS ON A CALCAREOUS LOAM SOIL

The zinc (Zn) requirement of a maize (Zea mays L.) hybrid (‘FHY-396’) and an indigenous variety (‘EV-7004’) was measured at low (22.4 ± 5°C) and high (28.8 ± 5°C) root-zone temperatures (RZT). Four Zn rates (0, 3, 9 and 27 mg kg^?1 soil) were applied to a calcareous loam soil in pots for the glasshouse study. Shoot and root dry matter yields were significantly more at the higher RZT. Regardless the RZT, maximum relative shoot dry matter yield in hybrid and variety was produced, respectively, at 9 and 3 mg Zn kg^?1 soil. Zinc concentration in roots and shoots of both the cultivars increased with Zn rates and it was significantly more at the higher RZT. Cultivars differed in critical Zn concentration (C_ZnC) required for maximum shoot dry matter yield. The C_ZnC ranged from 25 to 39 μg Zn g^?1 plant tissue for optimum growth of both the cultivars at low and high RZT.     

Potato tuber yield and quality in response to different nitrogen fertilizer application rates under two split doses in an irrigated sandy loam soil

Abstract

Management strategies to minimize nitrogen (N) losses to the atmosphere and water bodies from potato production fields while maintaining tuber yields and quality relies on good N management. A 2-year (2016–17 and 2017–18) field trial with ‘Symphonia’ potato was completed on a sandy loam soil irrigated with flood irrigation in Punjab, Pakistan to investigate the effect of N fertilizer rate on vegetative, yield and tuber quality parameters. The N fertilizer treatments comprising six N rates from 0 to 300?kg ha^?1 were applied at 50?kg N increments. Number of stems and tubers plant^?1 showed a quadratic response while other parameters revealed cubic trends in response to N fertilizer rates. Applying more than 250?kg ha^?1 of N fertilizer did not increase vegetative growth and yield. In conclusion, the optimal N-application rate of 250?Kg ha^?1 has great potential to improve yield and quality of potato in the sub-tropical region of Punjab, Pakistan. These findings, besides improving productivity can minimize the risk of N fertilizer loss to the atmosphere.     

Silicon application positively alters pollen grain area,osmoregulation and antioxidant enzyme activities in wheat plants under water deficit conditions

Role of exogenously-applied silicon (Si) on antioxidant enzyme activities was investigated in wheat under drought stress using a completely randomized factorial design with four replications. Drought stress significantly enhanced activities of ascorbate peroxidase, peroxidase, superoxide dismutase and catalase, and elevated accumulation of osmotically active molecules, soluble sugars and proline. Si application further enhanced activities of enzymes involved in oxidative defense system and accumulation of osmotically active molecules in drought-stressed plants. Under drought stress conditions, water shortage decreased protein content in all cultivars; however, application of Si increased it. Pollen area ratio was lower than 1 for cvs. Shiraz and Marvdasht under drought, but greater than 1 for cvs. Chamran and Sirvan. Water-limited regimes resulted in decreased leaf Ψ_w in all cultivars, but Si supply was effective in improving Ψ_w under water-limited regimes. Water shortage increased leaf K, Mg, and Ca concentrations. Under drought stress, Si-treated plants had higher K concentration than the none-treated plants.     

Fungal endophyte Penicillium janthinellum LK5 can reduce cadmium toxicity in Solanum lycopersicum (Sitiens and Rhe)

We investigated the role of gibberellins-producing endophyte Penicillium janthinellum LK5 associated with Solanum lycopersicum (host), abscisic acid (ABA)-deficient tomato mutant Sitiens and its wild-type Rheinlands Ruhm (Rhe) plants under cadmium (Cd) stress. A 100-μM Cd application to host, Sitiens and Rhe reduced the shoot growth, chlorophyll content and stomatal conductance. However, these parameters were significantly (P?<?0.0011) higher (1.0- to 2.6-folds) in host, Sitiens and Rhe under endophytic association than in non-endophyte infected plants (control) under Cd stress. Furthermore, endophytic association minimized the Cd-induced membrane injury and oxidative stress to host, Sitiens and Rhe plants by reducing electrolytes and lipid peroxidation while increasing the content of reduced glutathione and catalase activities as compared to non-endophyte-infected plants. Stress-responsive ABA content significantly increased (～2-folds) in Sitiens and Rhe under endophyte association, while in host plants it was decreased under Cd stress. Salicylic acid content was ～?1.7-fold higher in host, Sitiens and Rhe plants under Cd stress and endophyte association than in the control. Besides gibberellins production, the endophyte has the potential to solubilize phosphates (12.73?±?0.24 mg/l) since higher P was observed in the roots of Sitiens, Rhe and host plants. Similarly, nutrients like sulfur and calcium were more efficiently assimilated in roots of endophyte-associated plants than control under Cd stress. Conversely, Cd accumulation was significantly decreased (P?<?0.001) in the roots of endophyte-inoculated host, Sitiens and Rhe than control. In conclusion, endophyte symbiosis can counteract heavy metal stress which can exert negative effects on plant growth.     

REVIEW: Properties of Cereal Brans: A Review

Cereal brans are functional ingredients with high nutritive value and enormous health properties. Cereal brans have not been fully utilized in food systems despite their health benefits. This review presents an overview on the physical, chemical, microbiological, functional, and sensory properties of cereal brans for possible comparisons and selection to enhance the utilization of this underutilized milling fraction.     

Growth,survival, and heavy metal (Cd and Ni) uptake of spinach (Spinacia oleracea) and fenugreek (Trigonella corniculata) in a biochar‐amended sewage‐irrigated contaminated soil

Irrigation of arable land with contaminated sewage waters leads to the accumulation of trace metals in soils with subsequent phyto‐/zootoxic consequences. In this study, biochar derived from cotton sticks was used to amend an agricultural silt‐loam soil that had been previously irrigated with trace metal contaminated sewage waters. Metal accumulation and toxicity to spinach (Spinacia oleracea) and fenugreek (Trigonella corniculata) was investigated by measuring concentrations of Cd and Ni in plant tissues and various photosynthetic and biochemical activities of plants. Positive impacts of biochar on both spinach and fenugreek were observed in terms of biomass production that increased from 29% to 36% in case of spinach, while for fenugreek this increase was 32% to 36%. In the control treatment there was an increase in malondialdihyde, soluble sugar, and ascorbic acid contents, indicating heavy metal stress. Biochar applications increased soluble proteins and amino acids in plants and reduced the uptake of Cd from 5.42 mg kg^?1 at control to 3.45 mg kg^?1 at 5% biochar amended soil and Ni (13.8 mg kg^?1 to 7.3 mg kg^?1 at 5% biochar) by the spinach plants. In fenugreek, the Cd was reduced from 7.72 mg kg^?1 to 3.88 mg kg^?1 and reduction in Ni was from 15.45 mg kg^?1 to 9.46 mg kg^?1 at 5% biochar treated soil, reducing the possibility of transfer up the food chain. This study demonstrates that the use of biochar made from cotton‐sticks, as an amendment to arable soils that have received contaminated irrigation water, could improve plant growth and decrease Cd and Ni uptake to crops, alleviating some of the negative impacts of using sewage waters on arable land.