M. Yasin Ashraf

Salt tolerance potential in some members of Brassicaceae physiological studies on water relations and mineral contents

Salt tolerance potential of six cultivars of different brassica species and Eruca sativa was assessed in a field experiment conducted at Biosaline Research Station-II of NIAB, Faisalabad, Pakistan. Experiment consisted of four salinity treatments (i.e. 3.3, 11, 20, 27 dS/m). Cultivars Sheiaralle (B. napus), Peela Raya (B. carinata) and Chakwali Raya and RL-18 (B.juncea) produced significantly greater plant height, number of pods on main branch and yield per plot than others under all salinity treatments. These plants have potential to grow under saline condition and produced more than 50% seed yield up to 11 dS/m and approximately 50% up to 20 dS/m salt treatment. Experiment was repeated next year with two salt tolerant (RL-18 and Sheiaralle) and two salt sensitive cultivars (Brown Raya and Raya Anmol) under above mentioned conditions. Result showed that tolerant varieties have less Na+ content, water potential, osmotic potential while they have greater K+, Ca++ Mg++ content and turgor potential than sensitive ones. Effect of salinity on P content was not much pronounced in all brassica varieties.

Salinity induced changes in α-amylase and protease activities and associated metabolism in cotton varieties during germination and early seedling growth stages

The increase in salinity of the medium resulted in the decrease α-amylase and protease activities in all cotton varieties tested, however it was more pronounced in NIAB-86. Decrease in concentration of reducing and non-reducing sugars, slower mobilization of reserve protein and reduced amino acidslevels were observed with increase in salinity levels. However, varieties K-115 showed better performance than others. The variety K-115 also had a capacity to mobilization and had higher levels of sugars, total free amino acids and reserve protein during germination and early seedling growth stages. However, varieties K-115 showed better performance than others. Variety K-115 showed highest germination followed by NIAB-Karishma and NIAB-86. The variety K-115 also had a capacity to mobilization and had higher levels of total free amino acids and less reserve protein during germination and early seedling growth stages.

IMPROVEMENT IN YIELD AND QUALITY OF KINNOW (CITRUS DELICIOSA X CITRUS NOBILIS) BY POTASSIUM FERTILIZATION

Citrus, especially Kinnow, fruit yield and quality in Pakistan is not competitive with other countries, which could be mainly attributed to a lack of good nutrient management for citrus orchards. Many of the soils under these orchards have been reported as deficient in potassium (K). Therefore, work was initiated for improving citrus fruit yield, size, and quality through K nutrition management. Experiments were conducted in four districts of Punjab including Faisalabad, Toba Tek Singh, Jhang, and Sargodha and four rates of potash, i.e., 0, 50, 75 and 100 kg dipotassium oxide (K2O) ha−1 were applied using sulfate of potash (SOP) along with recommended rates of phosphorus (P) and nitrogen (N). Soils of all the selected sites were clay loam or sandy clay loam and deficient in K. The leaf analysis also showed that all the selected orchards were deficient in K. Application of K increased the fruit yield and quality but K at100 kg K2O ha−1 was more effective in increasing the fruit weight and size, and peel thickness than other K rates in all the selected orchards. Juice volume and percentage significantly increased when K was applied at 75 kg K2O ha−1 at all sites. Nutrient uptake like K, P, and N enhanced with the increase in K application rate, however, the highest calcium (Ca)+ magnesium (Mg) was recorded at 50 kg K2O ha−1. The results indicated that all rates of K application improved the fruit yield and quality and reduced fruit dropping, however, 75 kg K2O ha−1 rate was more effective as juice volume and percentage, total soluble solid (TSS)/acid ratio and nutrient uptake showed significant improvement.

Phytoremediation of Saline Soils for Sustainable Agricultural Productivity

Salinization of soils is one of the major factors which severely affect the agricultural productivity worldwide. Due to salinity, more than half a billion hectares of land are not being properly used for crop production. Thus, there is a need to search means to improve saline soils so that such soils could support highly productive and meaningful land-use systems to meet the current challenges of global food security. Although permanent solution of soil salinity problem necessitates a sound drainage system to manage the rising water table, this option, being energy- and cost-intensive cannot be employed on a large scale on vast areas. Phytoremediation or biological approach, i.e., plant-based strategies for improvement of deteriorated soils is an appropriate option. Phytoremediation of saline soils can be done by cultivating suitable plant species as well as by Exploiting the ability of plant roots to improve the dissolution and enhance levels of Ca in soil solution to efficiently remove Na from the soil cation exchange complex and leach it from the root zone. During the amelioration process, soil-aggregates stability, root proliferation, soil hydraulic properties and availability of nutrients to plants are also improved. Such improvement in soil properties facilitates cultivation of less tolerant plants, improves the environment in general, and the climatic conditions by enhancing carbon sequestration.

EFFECT OF SUPPLEMENTAL POTASSIUM (K+) ON GROWTH, PHYSIOLOGICAL AND BIOCHEMICAL ATTRIBUTES OF WHEAT GROWN UNDER SALINE CONDITIONS

Present experiment was conducted to assess the ameliorative effects of soil and foliar application of potash fertilizers, i.e., sulfate of potash (SOP) and muriate of potash (MOP) on five wheat cultivars (‘Sitta’, ‘Sehar’, ‘Bhakkar-2006’, ‘PFAU#VEE’, ‘S-24’), subjected to salt stress created by applying sodium chloride (NaCl; 10 dS m−1) to the growth medium. Different treatments of potash fertilizers used included: control, SOP (100 kg ha−1) in soil, foliar spray of 1% solution of SOP, MOP (100 kg ha−1) in soil and foliar spray of 1% solution of MOP. Experiment was carried out in completely randomized design with three replications. Imposition of salt stress reduced growth, yield, and related yield attributes, photosynthetic attributes, ionic contents and biochemical activities in all wheat cultivars. However, application of potash fertilizers in soil as well as in foliar spray counteracted the adverse effects of salt stress on all wheat cultivars and the application of SOP in soil and as a foliar spray proved to be more effective in inducing salt stress tolerance. No adverse effect of chloride on plant growth was observed. Among the cultivars, ‘S-24’ and ‘Sehar’ showed the maximum growth, yield and biochemical contents and thus could be used in future for obtaining better yield under saline conditions.

MODULATION OF PHYSIOLOGICAL AND BIOCHEMICAL METABOLITES IN SALT STRESSED RICE BY FOLIAR APPLICATION OF ZINC

An experiment was conducted to evaluate the effect of zinc (Zn) application on five rice cultivars grown under salt stress conditions. Two salinity levels of 0 and 10 dS m−1 were created with sodium chloride (NaCl) and foliar spray of Zn (0.05%; Chelated-Zn) was applied. A decrease in growth and yield related parameters were observed under salt stress, which was ameliorated in plants that received Zn foliar spray. Similar effects of salinity and Zn foliar spray were noted on photosynthetic rate, transpiration rate, stomatal conductance, water use efficiency, and water relations of plants. Salt induced increase in sodium (Na) content and decrease in other macro- and micronutrients contents were also reversed by Zn. Other salt tolerance indicating parameters likSe total free amino acids and total soluble sugars increased under Zn spray, clearing its role in improving salt tolerance.

Cadmium (Cd) and Lead (Pb) Induced Changes in Growth, Some Biochemical Attributes, and Mineral Accumulation in Two Cultivars of Mung Bean [Vigna radiata (L.) Wilczek]

ABSTRACT Addition of cadmium, lead, and cadmium + lead (Cd, Pb, and Cd+Pb) to growth medium leads to a reduction in seed germination, length, fresh and dry biomass of shoots and roots, total chlorophyll, chlorophyll a, chlorophyll b, and soluble proteins in plants. This study was undertaken on two mungbean cultivars (MN-92 and MN-98). Application of these metals in the growth medium reduced the bioabsorption of calcium (Ca), magnesium (Mg), and potassium (K). Concentrations of all the metals were greater in the roots than in the shoots except for K, which was greater in the shoots. Mungbean cultivar NM-98 performed better than NM-92 in response to heavy-metal toxicity. Overall, the metal-induced physiobiochemical changes resulted in reduced growth of both mungbean cultivars.

MODULATION IN YIELD AND JUICE QUALITY CHARACTERISTICS OF CITRUS FRUIT FROM TREES SUPPLIED WITH ZINC AND POTASSIUM FOLIARLY

Citrus, especially K innow (Citrus deliciosa × Citrus nobilis), fruit yield and quality in Pakistan is not competitive with that of other countries which could be mainly attributed to the lack of good nutrient management for citrus orchards. The yield losses in this fruit crop occur mainly due to heavy fruit dropping. Experiments to overcome these problems were conducted at four different sites one each in Faisalabad, Toba Tek Singh, Jhang and Sargodha districts of Punjab, Pakistan. The soil and leaf chemical analysis showed severe deficiency of Zn and our pervious results have shown that soil amendment with potassium (K) at 75 K2O kg ha−1 improved the citrus fruit yield and quality at all selected sites. In the present experiments, effect of foliar application of Zn and K alone or in combination was studied on nutrient uptake, fruit yield, fruit dropping and juice quality. The fruit trees were pretreated with a selected K level of sulfate of potash (SOP) or muriate of potash (MOP), i.e., 75 kg K2O ha−1 along with recommended nitrogen (N) and phosphorus (P) doses. Zinc [Zn, 1% zinc sulfate (ZnSO4) solution], K [1% potassium sulfate (K2SO4) solution] and Zn + K (solution containing 0.5% each of ZnSO4 and K2SO4) were sprayed at the onset of spring and flush of leaves or flowers, fruit formation and at color initiation on fruit. Overall, application of Zn, K or Zn + K was effective in improving the nutrient uptake, yield and quality parameters of citrus fruit at all sites. Fruit dropping was also reduced by the foliar spray of Zn, K or Zn + K but the most promising results were recorded with foliar spray containing both Zn and K.

Impact of chelators induced phytoextraction of cadmium on yield and ionic uptake of maize

ABSTRACT Enhanced phytoextraction uses soil chelators to increase the bioavailability of heavy metals. This study tested the effectiveness of ethylenediaminetetraacetic acid (EDTA) and citric acid in enhancing cadmium (Cd) phytoextraction and their effects on the growth, yield, and ionic uptake of maize (Zea mays). Maize seeds of two cultivars were sown in pots treated with 15 (Cd15) or 30 mg Cd kg−1 soil (Cd30). EDTA and citric acid at 0.5 g kg−1 each were applied 2 weeks after germination. Results demonstrated that the growth, yield per plant, and total grain weight were reduced by exposure to Cd. EDTA increased the uptake of Cd in shoots, roots, and grains of both maize varieties. Citric acid did not enhance the uptake of Cd, rather it ameliorated the toxicity of Cd, as shown by increased shoot and root length and biomass. Cadmium toxicity reduced the number of grains, rather than the grain size. The maize cultivar Sahiwal-2002 extracted 1.6% and 3.6% of Cd from soil in both Cd+ EDTA treatments. Hence, our study implies that maize can be used to successfully phytoremediate Cd from soil using EDTA, without reducing plant biomass or yield.

Salicylic Acid–Induced Growth and Biochemical Changes in Salt‐Stressed Wheat

The interactive effect of salicylic acid and sodium chloride (NaCl) salinity on wheat (Triticum aestivum L.) cv. ‘Inqlab’ (salt‐sensitive) and cv. ‘S‐24’ (salt‐tolerant) was studied in a sand‐culture pot experiment in a net house. Wheat seeds soaked in water and 100 ppm salicylic acid solution for 6 h were sown in sand salinized with 0, 50, and 100 mM NaCl. Pots were irrigated with quarter‐strength Hoaglands nutrient solution. Fourteen‐day‐old seedlings were harvested, and growth parameters (leaf and root length, leaf and root dry weight) were recorded. Chlorophyll a and b content; soluble sugar (reducing, nonreducing, and total sugars) content; nitrate (NR) and nitrite reductase activity (NiR); soluble proteins, and total soluble amino acid content of fresh leaves were determined. Sodium chloride salinity significantly reduced growth parameters. Salicylic acid treatment alleviated the adverse salinity effect on growth. Salinity decreased the chlorophyll a and b content and chlorophyll a/b ratio in both varieties, but a decrease in the chlorophyll a/b ratio was less in salt‐tolerant wheat variety (‘S‐24’), which could be a useful marker for selecting a salt‐tolerant variety. Salinity (NaCl) stress considerably increased the accumulation of reducing sugars, nonreducing sugars, and total soluble sugars in leaves of 14‐day‐old wheat seedlings of both varieties. The salt‐tolerant variety (‘S‐24’) accumulated a higher sugar content, which also could be a useful marker for selecting a salt‐tolerant variety for slat‐affected areas. Salinity caused a reduction in nitrate reductase and nitrite reductase activity. The salt‐tolerant variety (‘S‐24’) showed resistance to a decrease of nitrate reductase activity under salinity. This could be a useful criterion for selecting salt‐tolerant varieties. In response to salinity, wheat seedlings accumulated soluble proteins and amino acids, which might reflect a salt‐protective mechanism.