Terrestrial net primary production (NPP) quantifies the amount of atmospheric carbon fixed by plants and accumulated as biomass. Previous studies have shown that climate constraints were relaxing with increasing temperature and solar radiation, allowing an upward trend in NPP from 1982 through 1999. The past decade (2000 to 2009) has been the warmest since instrumental measurements began, which could imply continued increases in NPP; however, our estimates suggest a reduction in the global NPP of 0.55 petagrams of carbon. Large-scale droughts have reduced regional NPP, and a drying trend in the Southern Hemisphere has decreased NPP in that area, counteracting the increased NPP over the Northern Hemisphere. A continued decline in NPP would not only weaken the terrestrial carbon sink, but it would also intensify future competition between food demand and proposed biofuel production.

Drought-Induced Reduction in Global Terrestrial Net Primary Production from 2000 Through 2009

Agriculture and climate change are internally correlated with each other in various aspects, as climate change is the main cause of biotic and abiotic stresses, which have adverse effects on the agriculture of a region. The land and its agriculture are being affected by climate changes in different ways, e.g., variations in annual rainfall, average temperature, heat waves, modifications in weeds, pests or microbes, global change of atmospheric CO2 or ozone level, and fluctuations in sea level. The threat of varying global climate has greatly driven the attention of scientists, as these variations are imparting negative impact on global crop production and compromising food security worldwide. According to some predicted reports, agriculture is considered the most endangered activity adversely affected by climate changes. To date, food security and ecosystem resilience are the most concerning subjects worldwide. Climate-smart agriculture is the only way to lower the negative impact of climate variations on crop adaptation, before it might affect global crop production drastically. In this review paper, we summarize the causes of climate change, stresses produced due to climate change, impacts on crops, modern breeding technologies, and biotechnological strategies to cope with climate change, in order to develop climate resilient crops. Revolutions in genetic engineering techniques can also aid in overcoming food security issues against extreme environmental conditions, by producing transgenic plants.

Impact of Climate Change on Crops Adaptation and Strategies to Tackle Its Outcome: A Review.

Drought has been a major cause of agricultural disaster, yet how it affects the vulnerability of maize and wheat production in combination with several co-varying factors (i.e., phenological phases, agro-climatic regions, soil texture) remains unclear. Using a data synthesis approach, this study aims to better characterize the effects of those co-varying factors with drought and to provide critical information on minimizing yield loss. We collected data from peer-reviewed publications between 1980 and 2015 which examined maize and wheat yield responses to drought using field experiments. We performed unweighted analysis using the log response ratio to calculate the bootstrapped confidence limits of yield responses and calculated drought sensitivities with regards to those co-varying factors. Our results showed that yield reduction varied with species, with wheat having lower yield reduction (20.6%) compared to maize (39.3%) at approximately 40% water reduction. Maize was also more sensitive to drought than wheat, particularly during reproductive phase and equally sensitive in the dryland and non-dryland regions. While no yield difference was observed among regions or different soil texture, wheat cultivation in the dryland was more prone to yield loss than in the non-dryland region. Informed by these results, we discuss potential causes and possible approaches that may minimize drought impacts.

Global Synthesis of Drought Effects on Maize and Wheat Production

In the current scenario, it is an urgent requirement to satisfy the nutritional demands of the rapidly growing global population. Using conventional farming, nearly one-third of the crops get damaged mainly due to pest infestation, microbial attacks, natural disasters, poor soil quality, and lesser nutrient availability. More innovative technologies are immediately required to overcome these issues. In this regard, nanotechnology has contributed to the agrotechnological revolution that has imminent potential to reform the resilient agricultural system, while promising food security. Therefore, nanoparticles are becoming a new-age material to transform modern agricultural practices. The variety of nanoparticles-based formulations, including, nano-sized pesticides, herbicides, fungicides, fertilizers, and sensors, have been widely investigated for plant health management and soil improvement. In-depth understanding of plant and nanomaterial interactions opens new avenues towards improving crop practices through increased properties like disease resistance, crop yield, and nutrient utilization. In this review, we highlight the critical points to address the current nanotechnology-based agricultural research that could benefit productivity and food security in future.

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Nanoparticle-Based Sustainable Agriculture and Food Science: Recent Advances and Future Outlook

This article reviews recent literature on drought of the last millennium, followed by an update on global aridity changes from 1950 to 2008. Projected future aridity is presented based on recent studies and our analysis of model simulations. Dry periods lasting for years to decades have occurred many times during the last millennium over, for example, North America, West Africa, and East Asia. These droughts were likely triggered by anomalous tropical sea surface temperatures (SSTs), with La Ni˜ na-like SST anomalies leading to drought in North America, and El-Ni˜ no-like SSTs causing drought in East China. Over Africa, the southward shift of the warmest SSTs in the Atlantic and warming in the Indian Ocean are responsible for the recent Sahel droughts. Local feedbacks may enhance and prolong drought. Global aridity has increased substantially since the 1970s due to recent drying over Africa, southern Europe, East and South Asia, and eastern Australia. Although El Ni˜ no-Southern Oscillation (ENSO), tropical Atlantic SSTs, and Asian monsoons have played a large role in the recent drying, recent warming has increased atmospheric moisture demand and likely altered atmospheric circulation patterns, both contributing to the drying. Climate models project increased aridity in the 21 st century over most of Africa, southern Europe and the Middle East, most of the Americas, Australia, and Southeast Asia. Regions like the United States have avoided prolonged droughts during the last 50 years due to natural climate variations, but might see persistent droughts in the next 20–50 years. Future efforts to predict drought will depend on models’ ability to predict tropical SSTs. 2010 JohnWiley &Sons,Ltd.WIREs Clim Change2010 DOI:10.1002/wcc.81

Drought under Global Warming: A Review

Weed-competitive rice cultivars, a viable tool for integrated weed management of rice-field weeds, may greatly reduce the weed pressure and excessive dependence on herbicide in controlling weeds. Based on this premise, field experiments were conducted in 2018 and 2019 during the monsoon and winter rice-growing seasons at the Agronomy Field Laboratory of Bangladesh Agricultural University, Bangladesh, to evaluate the weed competitiveness of the selected rice varieties. A total of 42 monsoon and 28 winter rice varieties from Bangladesh were evaluated under “weedy” and “weed-free” conditions in the puddled transplanted system of cultivation. The field experiments were designed with three replications in a randomized complete block design. The results revealed that weed competition greatly reduces the yield of rice, and relative yield loss was 15–68% and 20–50% in monsoon and winter season rice, respectively. The lowest relative yield losses were recorded in monsoon rice from the variety BU dhan 1 (18%) and from the winter rice BRRI hybrid dhan5 (23.7%), which exhibited high weed tolerance. The weed competitive index (WCI) greatly varied among the varieties in both seasons and the monsoon season, ranging from 0.4 to 2.8, and the highest value was recorded from the hybrid variety Dhani Gold followed by BU dhan 1. In winter season rice, the WCI varied 0.25 to 2.4 and the highest value was recorded from the variety BRRI hybrid dhan3, followed by hybrid variety Heera 6. In monsoon rice, hybrid Dhani Gold was the most productive, but BU dhan 1 was the most weed competitive variety. Among the winter-grown varieties, the hybrid Heera 6 was the most productive, and the most weed competitive. Our research confirmed a high degree of variability in weed competitiveness among the 70 Bangladeshi rice varieties tested.

https://www.mdpi.com/2071-1050/13/9/5091/pdf

Preliminary Reports on Comparative Weed Competitiveness of Bangladeshi Monsoon and Winter Rice Varieties under Puddled Transplanted Conditions

To evaluate the comparative efficacy of different priming techniques and their effect on germination and seedling growth of soybean, a trial was executed in allelopathy laboratory of Department of Agronomy, University of Agriculture, Faisalabad, during 2009-10. The experimental design was completely randomized design (CRD) with three replications. Soybean seeds were subjected to hydro priming, on-farm priming, osmoperiming and moringa leaf extract priming. A control treatment was kept for comparison. The results revealed that all priming techniques were effective in increasing germination and seedling growth of forage soybean compared to control treatment,while moringa leaf extract priming was the most effective one in reducing time to start emergence (1.23 days) and time taken to 50% emergence (2.81 days). Root and shoot lengths were also significantly affected by all priming treatments, while priming with moringa leaf extract gave the highest root length (17.5 cm) and shoot length (19 cm). Similarly the highest root weight (0.19 g) and shoot weight (0.23 g) was also recorded by Moringa leaf extract priming. Regarding all parameters, hydropriming was statistically at par with Moringa leaf extract priming. On-farm priming performed better than osmopriming but was much less significant than Moringa leaf extract priming and hydropriming.

Evaluation of Forage Soybean (Glycine max L.) Germination and Seedling Growth Enhancement by Seed Priming Techniques

Under the changing climate, fertilization regimes and weed infestation management in aromatic direct-seeded fine rice (DSR) remain vital for curbing environmental hazards and ensuring food security. A multi-year field study was undertaken to appraise the influence of fertilization techniques and weed-free periods on weed dynamics, nutrient uptake and paddy yield in a semi-arid environment. Treatments included two fertilization methods (broadcasting and side placement) and five weed-free durations (20, 30, 40, 50 post-seeding days, DAS) along with a weed-free crop for a whole season. Weed competition for a season-long crop (weedy check) was maintained for each fertilizer application method. Our results revealed that the side placement of fertilizers resulted in a significantly lower weed density and biomass, even under season-long weed competition. The highest paddy yield was recorded for a crop without weeds, while weed-free duration of up to 50 DAS followed it. The uptake of nitrogen (N), phosphorus (P) and potassium (K) for a weed-free duration of up to 50 DAS were only 19%, 9% and 8%, respectively, as compared to the weedy check. The uptake of N, P and K by weeds in the broadcast method was 18%, 30% and 24% higher, compared to side-placed fertilizers. The period of 20–50 DAS remained critical in DSR as far as weed control was concerned. Thus, the side placement of fertilizers and controlling weeds for up to 50 days after rice sowing can be recommended for general adoption in semi-arid agro-ecological conditions.

Weed-Free Durations and Fertilization Regimes Boost Nutrient Uptake and Paddy Yield of Direct-Seeded Fine Rice (Oryza sativa L.)

A field trial was conducted to evaluate the effect of benzoic acid (an organic compound) and sorghum water extract (Sorgaab) at the Agronomic Research Area, University of Agriculture Faisalabad, during 2010-2011. Experiment was laid out in randomized complete block design (RCBD) with three replications. Benzoic acid and sorgaab were applied as foliar spray, alone and in different combinations at 22 days after sowing of wheat. All the treatments increased wheat yield as compared to control but the combined effect of benzoic acid and sorgaab was more pronounced than their sole effect. The highest grain yield (4.72 t ha -1 ) was recorded in plots treated with benzoic acid applied @ 6 kg ha -1 + sorgaab @ 12 L ha -1 (T8) which was 48% higher than control. Application of benzoic acid significantly affected all agronomic parameters as number of productive tillers per plant, number of grains per spike, 1000-grain weight, grain yield, biological yield as well as harvest index (HI) as compared to control. Significantly less total weed density, weeds fresh weight and dry weight were recorded in plots that were treated with 6 kg ha -1 + sorgaab @ 12 L ha -1 (T8).

AN APPRAISAL OF BENZOIC ACID AND SORGAAB EFFECT ON WEED MANAGEMENT AND WHEAT (Triticum aestivum L.) YIELD

Bee’s population is declining and disappearing at alarming rate. There are many factors responsible for declining the population of bees including diseases, natural enemies, environmental conditions and pesticides. Insecticides play its role dramatically for their population decline and neonicotinoid insecticides are critically important due to their wide application for pest control. Keeping in view of above problem, effect of neonicotinoid insecticides on olfactory learning behavior in Apis mellifera was observed using Proboscis Extension Reflex (PER) method. In this method, bees were harnessed in centrifuges tubes and feed on insecticides mixed sugar solution after three hours hunger. Bees were checked by feeding on non-treated sugar solution to observe PER response. Minimum proboscis extension was observed for acetamiprid and imidacloprid with 26% and 20% respectively at their recommend field doses while it was maximum for dinotefuran and thiamethoxam with 73% and 60% respectively. Only 40% bees showed response when exposed at 1/10 concentration of field dose for imidacloprid and the least at 11/00 of field dose. At control (Sugar solution) about 90% bees showed PER response. Among these neonicotinoid insecticides tested, imidacloprid and acetamiprid were the most damaging which impaired the olfactory learning performance in Apis mellifera

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Muhammad Aamir Iqbal

Papers

Preliminary Reports on Comparative Weed Competitiveness of Bangladeshi Monsoon and Winter Rice Varieties under Puddled Transplanted Conditions

Evaluation of Forage Soybean (Glycine max L.) Germination and Seedling Growth Enhancement by Seed Priming Techniques

Weed-Free Durations and Fertilization Regimes Boost Nutrient Uptake and Paddy Yield of Direct-Seeded Fine Rice (Oryza sativa L.)

AN APPRAISAL OF BENZOIC ACID AND SORGAAB EFFECT ON WEED MANAGEMENT AND WHEAT (Triticum aestivum L.) YIELD

Do neonicotinoid insecticides impaired olfactory learning behavior in Apis mellifera