Straw mulching with fertilizer nitrogen: An approach for improving crop yield,soil nutrients and enzyme activities

Field experiments were conducted to study soil properties, soil enzymes activities, water use efficiency (WUE) and crop productivity after six years of soya bean straw mulching in the semi‐arid conditions of China. The experiment included four treatments: CK (Control), N (240 kg N ha^‐1), H (soya bean straw mulching at half rate 700 kg ha^‐1 with 240 kg N ha^‐1) and F (soya bean straw mulching at full rate 1,400 kg ha^‐1 with 240 kg N ha^‐1). Soil organic carbon (SOC), soil labile organic carbon (LOC), soil available N (AN), available P (AP) and enzyme activities were analysed after wheat harvesting in 2016 and 2017. Results show that straw amounts had positive effects on the soil fertility indices being higher for treatment F. The SOC, LOC, AN, AP and enzyme activities (i.e. saccharase, urease and alkaline phosphatase) were in the order of F > H > N > CK. High wheat grain yield and WUE were observed for F treatment. A total of six years mulching along with 240 kg ha^‐1 nitrogen fertilizer application is sufficient for wheat yield stability and improving soil properties except urease activities in the semi‐arid condition of China. However, the straw mulching amount should be further studied with minimum nitrogen fertilizer for an environment‐friendly and effective approach for improving the soil biological properties with adequate crop production on a sustainable basis in the semi‐arid region of China.     

Drought Stress Impairs Grain Yield and Quality of Rice Genotypes by Impaired Photosynthetic Attributes and K Nutrition

正Drought is one of the most prevalent abiotic stresses that adversely affect rice productivity(Petrozza et al, 2014). Rice is very sensitive to drought stress and drought can cause 50% reduction in rice production globally(Yang et al, 2008). To meet the food needs for global population, 63% more agricultural production will be required by the year 2050 than     

Biochar Mitigates Salinity Stress in Potato

A pot experiment was conducted in a climate‐controlled greenhouse to investigate the growth, physiology and yield of potato in response to salinity stress under biochar amendment. It was hypothesized that addition of biochar may improve plant growth and yield by mitigating the negative effect of salinity through its high sorption ability. From tuber bulking to harvesting, the plants were exposed to three saline irrigations, that is 0, 25 and 50 mm NaCl solutions, respectively, and two levels of biochar (0 % and 5 % W/W) treatments. An adsorption study was also conducted to study the Na⁺ adsorption capability of biochar. Results indicated that biochar was capable to ameliorate salinity stress by adsorbing Na⁺. Increasing salinity level resulted in significant reductions of shoot biomass, root length and volume, tuber yield, photosynthetic rate (A_n), stomatal conductance (g_s), midday leaf water potential, but increased abscisic acid (ABA) concentration in both leaf and xylem sap. At each salinity level, incorporation of biochar increased shoot biomass, root length and volume, tuber yield, A_n, g_s, midday leaf water potential, and decreased ABA concentration in the leaf and xylem sap as compared with the respective non‐biochar control. Decreased Na⁺, Na⁺/K⁺ ratio and increased K⁺ content in xylem with biochar amendment also indicated its ameliorative effects on potato plants in response to salinity stress. The results suggested that incorporation of biochar might be a promising approach for enhancing crop productivity in salt‐affected soils.     

Determination of the role of salicylic acid and Benzothiadiazole on physico-chemical alterations caused by <Emphasis Type="Italic">Cucumber mosaic virus</Emphasis> in tomato

Shoe-string disease caused by Cucumber mosaic virus (CMV) is one of the major threats to tomato production worldwide. The alteration in some biochemical parameters in leaves of the susceptible tomato genotype (Nagina) associated with CMV infection and the effect of exogenous application of salicylic acid (SA) and benzothiadiazole (BTH) were studied in this paper. Results showed that exogenous treatment with SA and BTH not only led to plants which gave significantly more yield than diseased controls (DC), but also delayed symptom expression and reduced disease severity. Analysis of biochemical parameters indicated that exogenous application of elicitors and viral infection, significantly affected the activity of peroxidase (POD), superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Compared to the DC plants, minimum disease severity and maximum number of fruit were recorded after a single dose of SA + BTH. Maximum plant height was recorded after weekly application of SA and maximum fruit yield per plant was gained with single dose of SA. Moreover, the activity of POD was significantly elicited many-fold after weekly application of SA + BTH, while higher amount of SOD was recorded with single dose of SA. The activity of CAT was also significantly accelerated after weekly application of SA + BTH while increased level of APX was noticed with single dose of BTH. In conclusion, the combined application of SA and BTH played an important role in induction of defense mechanism against CMV infection and can be useful in tomato disease management programs.     

Exploring influential plant traits for enhancing upland cotton yield under salt stress

This research was conducted to explore genetic material that can yield better under salt stress conditions. The experiment was laid out using 27 upland cotton genotypes in a RCBD 2 factorial arrangement with two replications. Saline water (NaCl at 20 dS/m) was applied after satisfactory emergence was achieved. The crop was raised to maturity and data relating to yield, fiber quality and ionic traits were recorded. Analysis of variance showed significant variations in the germplasm. Plant height, bolls per plant, boll weight, GOT%, staple length, staple strength, K⁺ and K⁺/Na⁺ ratio under salinity stress showed a highly significant correlation with seed-cotton yield. The highest direct effect on seedcotton yield per plant was exhibited by bolls per plant and boll weight. The results from the correlation and path coefficient analyses revealed that although the K⁺/Na⁺ ratio had a strong positively significant association with seedcotton yield, its direct effect on the seed-cotton yield was negative and thus selection on the basis of K⁺/Na⁺ may not be fruitful. Hence, only indirect selection through bolls per plant and boll weight may be effective in increasing the seedcotton yield per plant under salinity stress.     

Genetic variability of heat tolerance, and its effect on yield and fibre quality traits in upland cotton (Gossypium hirsutum L.)

Global temperature is rising because of increasing concentrations of CO₂ and other greenhouse gases (e.g. methane, nitrous oxide, etc.) in the atmosphere because of the excessive use of fossil fuels. High temperature causes heat stress which reduces crop productivity. The development of heat-tolerant varieties is feasible and will help mitigate the effects of climate change. Fifty-one cotton accessions were screened in heat-stressed and non-stressed conditions in the glasshouse and field. Relative cell injury percentage (RCI %), a measure of cell membrane thermostability (CMT), was used to assess heat tolerance. Heat-tolerant accessions had more stable yield and yielded more seed cotton with better quality fibre than the heat-intolerant accessions across four environments. The responses of the 51 accessions to all four environments for the measured traits were strongly associated. RCI % of the accessions and hybrids was strongly and negatively associated with yield and fibre traits. CMT was concluded to be a useful technique for identification of heat-tolerant cotton.     

Genetic Variation in Cadmium Accumulation and Tolerance among Wheat Cultivars at the Seedling Stage

Exploitation of genetic differences to select wheat cultivars’ pollution-safe from cadmium (Cd) contamination requires better understanding of Cd uptake and translocation patterns. For this purpose, 15 wheat cultivars were grown in nutrient solution and exposed to four levels of Cd, i.e., 0, 15, 30, and 45 µM. The plants were harvested after 2 weeks of Cd exposure. Root and shoot relative dry matter (DM) was decreased in most of the cultivars, but some cultivars did not exhibit any toxic symptoms. The lowest Cd concentration in shoots was recorded for Lasani-2008 and Iqbal-2000 while the highest for Sehar-2006 and Inqlab-91. Both root absorption and translocation accounted for regulating Cd concentration in shoots. There was no relationship between relative DM and Cd concentrations in roots and shoots. The results suggest that wheat cultivars with low shoot Cd concentration but higher tolerance, i.e. Lasani-2008 and Iqbal-2000, could be used in breading programs for low Cd wheat.     

Effects of organic wastes,Glomus intraradices andPseudomonas putida on the growth of tomato and on the reproduction of the Root-knot nematodeMeloidogyne incognita

Effects of organic wastes (biosolids, horse manure, sawdust and neem leaf litter [NLL]), an arbuscular mycorrhizal (AM) fungusGlomus intraradices, and a plant growth-promoting rhizobacteriumPseudomonas putida, were studied on the growth of tomato and on the reproduction ofMeloidogvne incognita. Pseudomonas putida andG. intraradices promoted tomato growth in nematode-infected and nematode-free plants but growth promotion was higher in the infected ones. WhenP. putida andG. intraradices were applied together, the increase in tomato growth was greater than when either agent was applied alone. Of the organic wastes, NLL was better in improving tomato growth of nematode-infected plants followed by biosolids, horse manure and sawdust. Combined use of NLL withP. putida plusG. intraradices was best in improving growth of the infected plants. Root colonization byP. putida was increased more when inoculated withG. intraradices than when inoculated singly. Of the organic wastes, use of sawdust withP. putida caused a greater increase in root colonization by fluorescent pseudomonads followed by NLL, horse manure and biosolids. Nematode parasitism had an adverse effect on root colonization byP. putida. Inoculation ofP. putida and organic wastes increased the root colonization caused by the AM fungus.P. putida was better in reducing galling and nematode multiplication thanG. intraradices, whereas use of the two together was better than that of either of them alone. Among organic wastes, NLL was better in reducing galling and nematode multiplication followed by biosolids, horse manure and sawdust. Combined use of NLL withP. putida plusG. intraradices was better in reducing galling and nematode multiplication than any other treatment.     

Thermal tolerance, oxygen consumption and haemato-biochemical variables of Tor putitora juveniles acclimated to five temperatures

A 30-day acclimation trial was conducted using Tor putitora to elucidate its thermal tolerance, oxygen consumption, haemato-biochemical variables and selected enzymatic activities at five acclimation temperatures (AT). Juveniles of T. putitora were randomly distributed among five treatment groups (20, 23, 26, 29 and 32 ± 0.5 °C). There was a significant curvilinear increase in critical thermal maxima (CT_max) (y = ?0.0693x ² + 1.7927x + 34.628, R ² = 0.996) and lethal thermal maxima (LT_max) (y = ?0.1493x ² + 2.3407x + 35.092, R ² = 0.991) with increasing AT. The oxygen consumption rate increased significantly with increasing AT. The Q ₁₀ values were 1.16 between 20 and 23 °C, 3.09 between 23 and 26 °C, 1.31 between 26 and 29 °^C and 1.76 between 29 and 32 °C of AT. The acclimation response ratios were ranged between 0.37 and 0.59. Catalase, superoxide dismutase and ATPase activities were increased linearly in liver, gill and kidney, while brain acetylcholine esterase activity decreased linearly with increasing AT. Blood glucose remained unchanged up to AT of 26 °C and increased significantly at AT of 29 and 32 °C. Haemoglobin content was increased linearly with increasing AT. The highest WBC count was observed at 20 °C, and no significant changes found till AT of 26 °C and significantly decreased at 32 °C. Total serum protein and globulin were significantly decreased with increasing AT. Highest values were observed at 20 °C and remained consistent till 26 °C, then decreased significantly. There was no significant change in A/G ratio through the AT 20–29 °C and increased significantly at 32 °C. The increase in CT_max, LT_max and oxygen consumption rate with increasing AT may suggest that the thermal tolerance of T. putitora is dependent on its prior thermal exposure history, and it could adapt to higher AT by altering its haemato-biochemical variables.