A REVIEW ON OVERVIEW ROLE OF MUTATION IN PLANT BREEDING

Genetic diversity is the basis for plant breeders to develop new and improved cultivars with desirable, suited, and adaptive characteristics. Several factors such as hybridization, recombination, and mutation (Spontaneous and induced) are useful measures for providing variation in plants. However, naturally occurring mutation rate offers less for their optimum utilization. Hence induced mutation is considered to be a prime alternative other than naturally occurring variation. It has been considered a verified way of creating new variation within a crop variety which offers a possibility for the induction of desirable attributes which either can’t be expressed in nature or have been faded away during the process of evolution. Some of the mutant varieties of several crop species have led to a global contribution to crop improvement. The fate of the induced mutation largely depends on how induced mutagenesis underpins plants’ functional genome. Plant mutagenesis is had already played a significant role in crop improvement by successful enhancement of the yield, better nutritional quality, and wider adaptability. This review article is primarily centered around mutation, selection of mutant, how and when to use induced mutation, their treatment dose, and roles of mutation in Plant Breeding. Lastly, there still lies a huge potential aspect for future crop improvement through the application of induced mutation in plant species. In barley, a mutant that is resistant to mildew was 1st recorded in 1942. From the 170 diverse plant species, 3222 mutant varieties are evolved in 60 countries across the world officially. That release of varieties is possible due to the extensive use of induced mutation for 50 years in plant breeding activities all over the world. The modification of the nucleotides sequence of the genetic material of an organism, virus, extrachromosomal DNA is called a mutation. Mutagen is the agent causing mutation. There is extensive use of mutants in different subjects such as genetics, plant breeding, and plant physiology. Hugo deVries coined the term ‘mutation’ in 1901 to show sudden alteration in character considered to be heritable. Hence transmittable to the offspring while an agent causing mutation is called a mutagen. Mutation can occur naturally (spontaneous mutation) or by different agents such as chemical mutagen, ultraviolet light, x-rays, gamma rays, and so on (induced mutation). Mutagenesis is defined as the process in which the genetic information of an organism changed in a stable manner resulted in mutation.

CURRY LEAF: A REVIEW

Curry Leaf (Murraya koenigii) is native to South Asia famous among various cuisines for its flavor and aroma. Herbal drugs being relatively low cost with minimal side effects are used extensively in treating various diseases since ages. Curry Leaf occupies a huge space in traditional Ayurveda medicine. Small deciduous shrub with every part of medicinal properties and nutrition makes it a potential future industrial crop. Literatures suggest the antibacterial, antifungal, antiprotozoal activity of Murraya koenigii especially in leaf, stem, bark, and oil. The whole plant is used as tonic and stomachic properties. The aim of the present study is to review classification, origin, morphological characters, traditional use of curry leaf around the globe.

MUTATION BREEDING FOR CROP IMPROVEMENT: A REVIEW

Despite the fact that the world is at the rapid phase of agricultural modernization, but we are still concerned about food security. To meet the demand of exponential increase in population there is requirement of 70% more food by 2050. To overcome this situation we have to improve our existing crop varieties and make them genetically diverse, adaptive to climate change, input use efficient, high yielding, enhanced nutritional attributes, and better adaptable to a wide range of agro-ecosystems and should not deteriorate existing environment. Among the various methods of breeding to improve crop varieties mutation breeding (induced mutation) plays a crucial role for the development of genetic variation among themselves. Over past five decade mutation breeding is getting more popular and till now 3,362 mutant plant varieties from 240 different plant species in more than 75 countries are released. Different types of physical, chemical and combined mutagens have been used by various breeder to induce genetic variability in various crops. 2635 varieties are developed by physical mutagens, 398 varieties are developed by chemical mutagens and 37 varieties are developed by combination of physical and chemical mutagens. Continent wise, 82 varieties are developed by Africa, 2049 by Asia, 10 by Australia and Pacific, 959 by Europe, 53 by Latin America, and 209 by North America. Similarly, 1602 major cereals, 501 major legumes and 86 major oil seed mutant crop varieties are developed by mutation breeding/induced mutation. Mutation breeding improve several qualitative and quantitative characters of crop plant and is successfully applied in several cereal, grain legume, oil seed, vegetable, fruits, medicinal plant, ornamental plants and fodder crops. With the advancement of various plant breeding, genetics, and biotechnological tools mutation breeding contribute toward the increase in global food and agriculture production which ultimately overcome global hunger and improve the nutritional status of the globe.

INTEGRATED NUTRIENT MANAGEMENT IN MAIZE PRODUCTION – A REVIEW

Maize is one of the main staple crops of Nepalese diet grown throughout the country during summer season as single crop or relayed with millet. This short review article analyses the previous works & studies on impact of INM in maize production. Long-time research which was conducted in different areas has shown that in addition to natural resources deterioration, abiotic-biotic stress, deficiency of several macro & micro nutrients is also an essential factor which influences yield reduction, productivity declination, and shrinkage in net profit. Therefore, Integrated use of chemical and organic fertilizer on yield and yield attributes component of maize is very crucial for assurance of food security & food self-sufficiency. Integrated Nutrient Management (INM) aims at adjustment of soil fertility and plant nutrient supply to an optimum level for sustaining the desired crop productivity through optimization of benefit from all possible sources of plant nutrients. The integrated use of major plant nutrients (nitrogen, phosphorus, and potash) along with different organic carbon sources (animal manures and plant residues) together with bio-fertilizers (beneficial microbes) significantly improves maize growth, yield and yield components together with grower’s income.

REVIEW ON WEED CONTROL IN GLYPHOSATE TOLERANT MAIZE

Weeds are a constant nuisance for farmers, which steal space and nutrients from the crops. Weed management is the botanical component which attempts to stop noxious weeds from competing with desired flora and fauna including domesticated plants. It is preventing of non-native species competing with native species. Growth of various weeds has been major problem in the yield of many plants. It has also affected the growth and development of maize as it competes with the space and nutrients. Different weed management techniques have been introduced till date to increase the yield and to control the weeds, also, aiming less effect of the techniques on the main plant. Generally, preventive, biological, cultural, mechanical and chemical weed control methods are used. Advancements in plant biotechnology have allowed the development of a number of herbicide resistant crops which is a success in chemical weed management of the crops. They have provided the requisite tools to transform the plants to contain the foreign genes. Genetically engineered herbicide resistant crops have been widely planted globally since their introduction in 1995. These developments offer new approaches to managing weeds in cropping systems. This technology offers some advantages over currently used systems.

IMPACT OF POSTHARVEST OPERATIONS ON RICE GRAIN QUALITY: A REVIEW

An efficient postharvest system aims to minimize the loss and obtained the good quality rice gain. This review summarizes the information regarding the postharvest processing published by various authors and outline the evidence that support the impacts of the postharvest handling on rice grain quality. Grain quality, includes a summary of the physical and chemical characteristics of rice grain. It has many components such as nutritional value, appearance, cooking and eating quality. Drying of rice mainly affects the milling quality, as most breakage of rice occurs because of grain fissuring. Rice ageing occurs during storage is responsible for the changes in pasting properties, color, flavor and chemical composition such as starch, protein, lipid etc. that affect rice quality. Therefore, research on various drying methods, storage conditions and milling methods should be maximized and maintain the desired rice grain quality. This review may contribute to understand the impacts of postharvest processes on grain quality and can increase the head rice yield.

HOME GARDEN, ALONG WITH ITS FUNCTIONAL CATEGORY AND KEY SPECIES REPORTED IN NEPAL: A REVIEW

Home gardening is performed from an ancient period in Nepalese societies. More than 74.5% of the population of the country is involved in an agriculture-based profession in Nepal. Home gardens include the versatile species of trees, vegetables, annual and perennial vegetables, birds and animals, medicinal herb plants on the same land units in a geometric or dimensional proportion. this paper focuses on the presentation of home garden status and present scenario and its interlinkages with home garden. Though sufficient work on home garden has been done but still focus on self-sufficiency and their role in food security has not been reported. The home garden species was found to be of great importance as they play a vital role in conservation of key species.

COMPARATIVE ADVANTAGE OF ARECA NUT OVER RICE IN JHAPA, NEPAL

This study was conducted to assess comparative economic analysis of the areca nut and rice production. This study also aimed to assess the major governing factors and overall economy involved in the production, major problems leading to shift rice farming, key determinants of areca nut production in the study area. Seventy areca nut growers were selected by simple random technique and thirty rice growers were selected by purposive sampling technique. Three potential areas of Jhapa district: Mechinagar municipality 1, 2, 3, 4; Buddhashanti and Arjundhara were selected as the survey site where there is major shifting of rice cultivation for commercial areca nut farming. The data collection was done from both primary and secondary sources. Descriptive statistics benefit cost analysis, resource use efficiency through Cobb-Douglas economic model was used to analyze data using SPSS. It was found that areca nut production had significantly higher gross return in comparison to rice whose production was affected by factors viz. labor, manure, chemical fertilizers, pesticides and irrigation in areca nut while machineries use, chemical fertilizers, seeds, manure and labor for rice production. The major reason for adopting areca nut cultivation was easier in cultivation practice, low cost of cultivation and high economic return. The B/C ratio of areca nut and rice was 2.02 and 0.99 respectively which was statistically significant. The productivity of the areca nut can be increased by adopting improved cultivation practices and scientific technology. Since, agro climatic conditions favors the production of areca nut cultivation, it should be shifted from small scale to commercialized form.

SEED HYDROPRIMING TECHNIQUE IN CEREAL CROPS: A REVIEW

Cereals contribute to 50% of total caloric intake and 95% of the total food requirement globally. Increasing climate change and population has increased the food demand and endangered the productivity of food crops due to various biotic and abiotic stresses and within these conditions’ world is trying to push itself towards increasing the grain yield per unit of land. Several methods of seed priming are practiced to rejuvenate the seeds and remove the environmental stress. Hydro priming, a method of seed priming, has prominent advantage of stresses resistance, better crop stand, and emergence. In order to cope with the future challenges of crop productivity knowledge on the beneficial effects of hydro priming is important. Hydro priming induces DNA repair processes and Antioxidant responses associated as pre-germinative metabolism that leads to early and better seedling growth. Seed Hydro priming may be the best solution to the germination related problems especially in crops grown in unfavorable conditions and enhanced activation of the plant defense mechanism describes this process. Defining the exact treatment duration, water volume, and temperature of water during Hydro priming can revolutionize the farming system with better results.

AN OVERVIEW OF AZOLLA IN RICE PRODUCTION: A REVIEW

Azolla is a free-floating water fern which in symbiotic association with cyanobacterium Anabaena azollaefixes the atmospheric nitrogen. Nitrogen fixing ability of cyanobacterialsymbiont varies between 30 and 60 kg N ha−1 which designates Azolla as an important biological nitrogen source for rice ecosystem. Inoculation of Azolla is an alternative and sustainable source of nitrogen to increase the rice productivity and it also can decrease the use of synthetic fertilizer. A number of past researches prove that Azolla has been used as apotential biofertilizer for rice production. Azolla is either incorporated in the soil before rice transplanting or grown as a dual crop along with rice. The objective of this paper is to provide a brief account of importance as well as developments in the utilization of Azolla-Anabaena system in agriculture, mainly rice production.