Ghulam Mustafa Shah

Potassium applied under drought improves physiological and nutrient uptake performances of wheat (Triticum Aestivun L.)

The physiological and nutrient uptake performance of two wheat (Triticum aestivum L.) cultivars (Lasani-2008 and Auqab-2000) to foliar application of 1% potassium (K) at three different growth stages (tillering, flower initiation and grain filling) was investigated under water limited environment in a wire house experiment at the Nuclear Institute for Agriculture and Biology, Faisalabad. The aim was to find out the best K application stage for improvement in drought tolerance potential. Drought stress was created by withholding irrigation at the three growth stages and then K was sprayed with carboxymethyl cellulose as a sticking agent, whereas Tween-20 was used as a surfactant for foliar spray. At maturity, aboveground nitrogen, phosphorus, K, sodium and calcium uptakes by the crop were measured. Besides, water potential, osmotic potential and turgor potential of crop were also estimated. The results indicated that the drought stress at all three critical growth stages of wheat adversely affected plants nutrient uptake, water potential, osmotic potential and turgor potential of wheat plants. The exogenous application of K under drought stress at all three critical growth stages enhanced tolerance of wheat by reducing toxic nutrients uptake and improving the physiological efficiency. In this regards, both varieties showed uniform behavior. Maximum improvement in all the recorded nutrients uptake and physiological parameters was achieved when K was applied at grain filling stage of both cultivars.

Exogenous application of glycinebetaine and potassium for improving water relations and grain yield of wheat under drought

Compatible solutes rescue plants in the hour of intense water deficit conditions. Glycinebetaine (GB) and potassium (K) are main solutes, playing role in improving plant water potential and ultimately the crop yield. However, only a few attempts have been made so far to study their optimum dozes and interactions to ameliorate the drought stress in wheat. To explore this, GB solutions of 0, 50,100 and 150 mM concentration and K solutions of 0, 0.5, 1.0, and 1.5% concentration were sprayed at milking stage of two wheat varieties under stress (Auqab-2000; drought sensitive and Lasani-2008; drought resistant). The stress was created by withholding water up till appearance of wilting symptoms and then the solutes (alone and/or in combination) were sprayed with carboxymethyl cellulose as a sticking agent, whereas Tween-20 was used as a surfactant for foliar spray. At maturity, ten random plants from field-experiments and three in case of pot experiment were selected to estimate plant height, spike length, number of spikelets spike-1 , number of grains spike -1 , and grain yields. Besides, water potential, osmotic potential and turgor potential of crop were also estimated. The results indicated that the drought stress adversely affected all the above parameters. The exogenous application of GB and K to wheat significantly improved spike length, number of grain per spike and grain yields. Moreover, a significant interaction between these solutes was observed since at a given level of GB all these yield parameters were increased (p < 0.05) with K concentration. The highest values were obtained when GB and K were applied in combination at 100 mM and 1.5%, respectively. The same treatment also improved the leaf water potential, osmotic potential and turgor potential to maintain plant water potential gradient under stress. These findings lead us to conclude that application of GB and K (100 mM and 1.5%, respectively) is the best strategy to ameliorate the drought impact on wheat at milking stage with improved production.

Simulation of Long-Term Carbon and Nitrogen Dynamics in Grassland-Based Dairy Farming Systems to Evaluate Mitigation Strategies for Nutrient Losses.

Many measures have been proposed to mitigate gaseous emissions and other nutrient losses from agroecosystems, which can have large detrimental effects for the quality of soils, water and air, and contribute to eutrophication and global warming. Due to complexities in farm management, biological interactions and emission measurements, most experiments focus on analysis of short-term effects of isolated mitigation practices. Here we present a model that allows simulating long-term effects at the whole-farm level of combined measures related to grassland management, animal housing and manure handling after excretion, during storage and after field application. The model describes the dynamics of pools of organic carbon and nitrogen (N), and of inorganic N, as affected by farm management in grassland-based dairy systems. We assessed the long-term effects of delayed grass mowing, housing type (cubicle and sloping floor barns, resulting in production of slurry and solid cattle manure, respectively), manure additives, contrasting manure storage methods and irrigation after application of covered manure. Simulations demonstrated that individually applied practices often result in compensatory loss pathways. For instance, methods to reduce ammonia emissions during storage like roofing or covering of manure led to larger losses through ammonia volatilization, nitrate leaching or denitrification after application, unless extra measures like irrigation were used. A strategy of combined management practices of delayed mowing and fertilization with solid cattle manure that is treated with zeolite, stored under an impermeable sheet and irrigated after application was effective to increase soil carbon stocks, increase feed self-sufficiency and reduce losses by ammonia volatilization and soil N losses. Although long-term datasets (>25 years) of farm nutrient dynamics and loss flows are not available to validate the model, the model is firmly based on knowledge of processes and measured effects of individual practices, and allows the integrated exploration of effective emission mitigation strategies.

Zinc oxide nanoparticles affect carbon and nitrogen mineralization of Phoenix dactylifera leaf litter in a sandy soil

We investigated the impact of zinc oxide nanoparticles (ZnO NPs; 1000mgkg-1 soil) on soil microbes and their associated soil functions such as date palm (Phoenix dactylifera) leaf litter (5gkg-1 soil) carbon and nitrogen mineralization in mesocosms containing sandy soil. Nanoparticles application in litter-amended soil significantly decreased the cultivable heterotrophic bacterial and fungal colony forming units (cfu) compared to only litter-amended soil. The decrease in cfu could be related to lower microbial biomass carbon in nanoparticles-litter amended soil. Likewise, ZnO NPs also reduced CO2 emission by 10% in aforementioned treatment but this was higher than control (soil only). Labile Zn was only detected in the microbial biomass of nanoparticles-litter applied soil indicating that microorganisms consumed this element from freely available nutrients in the soil. In this treatment, dissolved organic carbon and mineral nitrogen were 25 and 34% lower respectively compared to litter-amended soil. Such toxic effects of nanoparticles on litter decomposition resulted in 130 and 122% lower carbon and nitrogen mineralization efficiency respectively. Hence, our results entail that ZnO NPs are toxic to soil microbes and affect their function i.e., carbon and nitrogen mineralization of applied litter thus confirming their toxicity to microbial associated soil functions.

Effect of water management and silicon on germination, growth, phosphorus and arsenic uptake in rice

Silicon (Si) is the 2nd most abundant element in soil which is known to enhance stress tolerance in wide variety of crops. Arsenic (As), a toxic metalloid enters into the human food chain through contaminated water and food or feed. To alleviate the deleterious effect of As on human health, it is a need of time to find out an effective strategy to reduce the As accumulation in the food chain. The experiments were conducted during September-December 2014, and 2016 to optimize Si concentration for rice (Oryza sativa L.) exposed to As stress. Further experiment were carried out to evaluate the effect of optimum Si on rice seed germination, seedling growth, phosphorus and As uptake in rice plant. During laboratory experiment, rice seeds were exposed to 150 and 300µM As with and without 3mM Si supplementation. Results revealed that As application, decreased the germination up to 40-50% as compared to control treatment. Arsenic stress also significantly (P < 0.05) reduced the seedling length but Si supplementation enhanced the seedlings length. Maximum seedling length (4.94cm) was recorded for 3mM Si treatment while, minimum seedling length (0.60cm) was observed at day7 by the application of 300µM As. Silicon application resulted in 10% higher seedling length than the control treatment. In soil culture experiment, plants were exposed to same concentrations of As and Si under aerobic and anaerobic conditions. Irrigation water management, significantly (P˂0.05) affected the plant growth, Si and As concentrations in the plant. Arsenic uptake was relatively less under aerobic conditions. The maximum As concentration (9.34 and 27.70mgkg DW-1 in shoot and root, respectively) was found in plant treated with 300µM As in absence of Si under anaerobic condition. Similarly, anaerobic condition resulted in higher As uptake in the plants. The study demonstrated that aerobic cultivation is suitable to decrease the As uptake and in rice exogenous Si supply is beneficial to decrease As uptake under both anaerobic and aerobic conditions.

Effect of storage conditions on losses and crop utilization of nitrogen from solid cattle manure

The objectives of the present study were to quantify the effects of contrasting methods for storing solid cattle manure on: (i) total carbon (C) and nitrogen (N) balances during storage, and (ii) crop apparent N recovery (ANR) following manure application to arable land, with maize as a test crop. Portions of 10 t of fresh solid cattle manure were stored for 5 months during 2009/10 in three replicates as: (i) stockpiled heaps, (ii) roofed heaps, (iii) covered heaps and (iv) turned heaps at Wageningen University, the Netherlands. Surface emissions of ammonia (NH 3 ), nitrous oxide (N 2 O), carbon dioxide (CO 2 ) and methane (CH 4 ) were measured regularly using a static flux chamber connected to a photo-acoustic gas monitor. Total C and N losses during storage were determined through the mass balance method. After storage, the manures were surface-applied and incorporated into a sandy soil, and maize ANR was measured as a proportion of both N applied to the field (ANR F ) and N collected from the barn (ANR B ). During the storage period, the average losses of initial total N (N total ) were 6% from the covered, 12% from the roofed, 21% from the stockpiled and 33% from the turned heaps. Of the total N losses, 2–9% was lost as NH 3 -N, 1–4% as N 2 O-N and 16–32% through leaching. However, the greatest part of the total N loss from the four storage methods was unaccounted for and constituted in all probability of harmless dinitrogen gas. Of the initial C content, c. 13, 14, 17 and 22% was lost from the covered, stockpiled, roofed and turned heaps, respectively. Maize ANR F was highest from covered (39% of the applied N) followed by roofed (31%), stockpiled (29%) and turned manure (20%). The respective values in case of maize ANR B were 37, 27, 23 and 13%. It is concluded that from a viewpoint of on-farm N recycling the storage of solid cattle manure under an impermeable plastic cover is much better than traditional stockpiling or turning heaps in the open air.

Yield and nitrogen use efficiency of rice-wheat cropping system in gypsum amended saline-sodic soil

It is critical to determine nitrogen use efficiency (NUE) to find to which extent higher rates of nitrogen can improve crop yield with effective management practices. Two-year field experiments were conducted to investigate yield and NUE of rice-wheat cropping system on saline-sodic soil. Treatments included were two nitrogen (N) application rates, i.e. 15% (N115) and 30% (N130) higher than the recommended rates for normal soil, along with gypsum at the rates of 50% (SGR50) and 100% (SGR100) of soil gypsum requirement. Results revealed relatively highest NO3 leaching for rice (161 and 145 mg L-1) and for wheat (97 and 93 mg L-1) during 2011-12 and 2012-13, respectively in N130 + SGR100. In this treatment, crop yield and NUE were the highest as compared to the other combinations. This resulted in reduction of yield gap by two-fold (53% to 26%) between saline-sodic and normal soils for rice-wheat. Interestingly, N130 + SGR100 proved most effective during the first year, however, N100 + SGR100 became more profitable in the subsequent year. Pearson correlation coefficients predicted significant positive correlation (p < 0.01) of yield and NUE with soil organic matter, cation exchange capacity and infiltration rate while inverse relationship was observed with electrical conductivity, pH, CaCO3, and bulk density. Based on data, it is concluded that the recommended N application together with SGR100 would be environmental-friendly and economically viable option for rice-wheat cropping system in saline-sodic soils.

Cadmium tolerance and phytoremediation potential of acacia (Acacia nilotica L.) under salinity stress

ABSTRACT In this study, we explored the effect of salinity on cadmium (Cd) tolerance and phytoremediation potential of Acacia nilotica. Two-month-old uniform plants of A. nilotica were grown in pots contaminated with various levels of Cd (0, 5, 10, and 15 mg kg−1), NaCl (0%, 0.5%, 1.0% (hereafter referred as salinity), and all possible combinations of Cd + salinity for a period of six months. Results showed that shoot and root growth, biomass, tissue water content and chlorophyll (chl a, chl b, and total chl a+b) contents decreased more in response to salinity and combination of Cd + salinity compared to Cd alone. Shoot and root K concentrations significantly decreased with increasing soil Cd levels, whereas Na and Cl concentrations were not affected significantly. Shoot and root Cd concentrations, bioconcentration factor (BCF) and translocation factor (TF) increased with increasing soil Cd and Cd + salinity levels. At low level of salinity (0.5%), shoot and root Cd uptake enhanced, while it decreased at high level of salinity (1.0%). Due to Cd tolerance, high shoot biomass and shoot Cd uptake, this tree species has some potential for phytoremediation of Cd from the metal contaminated saline and nonsaline soils.

Anaerobic degradation of municipal organic waste among others composting techniques improves N cycling through waste-soil-plant continuum

This study aimed to examine the effect of composting techniques of municipal organic solid waste (MSW) for (i) total carbon (C), nitrogen (N) losses, and changes in its chemical characteristics during composting phase and (ii) value of the composted materials as fertilizer when applied to vegetables. Treatments included: aerobic composting (AC), anaerobic composting (ANC), co-composting (CC) and open dumping (OD) for 4 months. During the composting phase, about 61, 50, 35, and 13% of the initial N was lost from CC, AC, OD, and ANC, respectively. The respective values in case of total C loss were 17, 13, 14 and 11%. After field application, about 41% of the applied organic N was mineralized from ANC material, whereas the respective values for OD, CC and AC were 25-26, 15-16, and 12-19%. Consequently, dry matter (DM) yield and vegetable N uptake from the resultant compost were in the order ANC>OD>CC>AC. Moreover, vegetable apparent N recovery (ANRf) was the highest from ANC (spinach: 36 and carrot: 45%) followed by OD (26 and 34%), CC (18 and 26%) and AC (18 and 24%) material. When composting N losses were taken into account during calculations, about 31-39, 17-22, 9-10, and 7-12% of the N collected from filth depots ended up in plants from ANC, OD, CC and AC, respectively. We concluded that ANC results in least C and N losses during the composting phase and greatest N mineralization in the soil, which enhances vegetable yield, N recovery and thereby the N cycling through waste-soil-plant continuum.

Amelioration of saline–sodic soil with gypsum can increase yield and nitrogen use efficiency in rice–wheat cropping system

ABSTRACT A 2-year field experiment was conducted to determine crop yield and N use efficiency (NUE) from a saline–sodic soil (clay loam) with and without application of gypsum. Treatments included two N application rates (15% and 30%) higher than the recommended one to the normal soil, and gypsum added at 50% and 100% of soil gypsum requirement (SGR) to the saline–sodic soil, both cultivated with rice and wheat during 2011–2013. Results revealed a decrease in pH of saturated soil paste (pHs), electrical conductivity of saturation extract (ECe), sodium adsorption ratio (SAR) and exchangeable sodium percentage with N fertilizer along with gypsum application in saline–sodic soil. However, the effect was most prominent when gypsum was added at 50% of SGR. Crop yield and NUE remained significantly lower (p < 0.05) in saline–sodic-soils as compared to normal soil. However, gypsum application reduced this difference from 47% to 17% since both yield and NUE increased considerably. Crop yield and NUE remained higher for wheat than for rice. During first year, higher doses of N with gypsum application at 50% SGR proved most effective, whereas, in subsequent year, recommended N along with gypsum at 50% SGR became more profitable. All these results lead us to conclude that gypsum application can ameliorate saline–sodic soil thereby increasing crop yield and NUE.