Aquatic weeds are higher plants found in the aquatic ecosystem and in anaerobic rice fields, where they have no economic benefits. The continuance of aquatic weeds is more widespread than terrestrial weeds because in aquatic ecosystems there is very little fluctuation in the environmental conditions compared with terrestrial ecosystems. Scientists have been working to address the harmful allelopathic effects of aquatic weeds on the aquatic ecosystem, but limited information is available on the allelopathic influence of aquatic weeds on agro-ecosystems through the release of phytotoxic compounds. Phytotoxic chemicals released by different aquatic weeds into irrigation water and/or directly into rice ecosystems might have a significant inhibitory influence on germination, growth and yield field crops, soil properties and nutrients availability, population and community structure, and weed invasion. However, aquatic weeds might also be used as a potential organic alternative to chemical weed-control, due to the higher susceptibility of terrestrial weeds to the phototoxic chemicals released by aquatic weeds. Natural alternatives to chemical weed control are need of time and are crucial for a sustainable weed control. Chemical weed control is challenged, due to recent increases in herbicides resistance from weeds and to the harmful side-effects of herbicides on the environment. This review is focused on the influence of aquatic weeds on agro-ecosystems, with examples of common weeds in aquatic ecosystems and invasive aquatic weeds found in anaerobic rice.
Drip irrigation has long been proven beneficial for fruit and vegetable crops in Pakistan, but the only barrier in its adoption is the high cost of installation for small landholders, which is due to overdesigning of the system. In the present study, the cost of a conventional drip irrigation system was reduced by redesigning and eliminating the heavy filtration system (i.e., hydrocyclon, sand media, disc filters (groundwater source), pressure gauges, water meters, and double laterals).Purchasing the drip system from local vendors also reduced the cost. Field trials were conducted during 2015 and 2016 to observe the productive and economic effects of low-cost drip irrigation on vegetables (potato, onion, and chilies) and fruits (olive, peach, and citrus). The low-cost drip irrigation system saved 50% cost of irrigation and increased 27–54% net revenue in comparison with the furrow irrigation system. Further, water use efficiency (WUE) was found from 3.91–13.30 kg/m3 and 1.28–4.89 kg/m3 for drip irrigation and furrow irrigation systems, respectively. The physical and chemical attributes of vegetables and fruits were also improved to a reasonably good extent. The present study concluded that low-cost drip irrigation increased the yield by more than 20%, as compared with traditional furrow irrigation, and thus, it is beneficial for the small landholders (i.e., less than 2 hectares).
Three rusts are destructive, diminishing produce and nutritious value significantly, affect food availability and consequently food security through reductions in yield. In agricultural research institutes with mandate of wheat improvement, incorporating genes resistant against rust is matter of routine. The dilemma of rusts in wheat has been addressed the most, leading to discovery of principles of plant breeding for resistance e.g. gene disease genes inherit following Mendelian genetics, concept of genetic diversity and concept of gene for gene theory. Two strategies of breeding wheat for disease resistance are being followed. 1- Conventional and 2- Advanced. Among conventional approaches selection and hybridization are well known. However rust resistance has been found short lived and may also be durable in certain cases. Durability of disease resistance is desired and has been explored widely. Durability of resistance is generally attained through incorporation of genes effective at adult plant stage and combination of quantitative genes. Application of biotechnology to improve productivity of rust resistance breeding is the usage of molecular markers in pyramiding genes and substantiates the existence of genes in, and confirming released cultivars are pure. This involves molecular markers that are precise and pertinent across extensive ranges of breeders’ germplasm. This review article encompasses all features of wheat development through application of different techniques of wheat improvement. However, despite development of novel approaches that has accelerated wheat breeding, breeding in pathogen leading to producing more virulent strains. Consequently, wheat breeding is a continuous process.
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