eChapters

Weeds are unwanted and undesirable plants which interfere with the utilization of land and water resources and thus adversely affect human welfare. They can also be referred as plants out of place. Weeds rank first among different agricultural pests causing crop loss. About 30,000 species of weeds have been listed in the world, out of which 18,000 cause serious damage in different ways resulting in considerable loss to agricultural production.

1. DEFINITIONS

Various definations of weed have been proposed. Weed is defined as a valueless plant growing wild, especially one that grows on cultivated ground to the exclusion or injury of the desired crop. Weed means any undesirable or troublesome plant, especially one that grows profusely where it is not wanted. The weed have also been defined a plant considered undesirable. Weeds are commonly unwanted plants in human-controlled settings, such as farm fields, gardens, lawns and parks. A weed may be any plant that grows or reproduces aggressively, or is outside its native habitat. Some plants that often are considered to be weeds are Bermuda grass, creeping Charlie, dandelion, golden rod, poison ivy, ragweed, wild carrot, wood sorrel, nutsedge etc.

The term weed can be described in many ways. In general, it is said that weed is a plant, which is not sown by the farmers or which is out of place. Weed is defined as the unwanted, undesirable plant, growing out of its proper place, which interferes with the utilization of natural resources, is prolific, persistent, competitive, harmful and even poisonous in nature and can grow in adverse climatic conditions.There are more than 30,000 species of weeds distributed world over, out of which 18,000 are noxious and cause serious losses. Around 250 species are causing serious economic losses. Weeds in orchards reduce crop yields by competing for moisture, nutrients, light and space. They also act as a host for insect pests and diseases. When they become large, they interfere with orchard operations as well as water bodies. There are some weeds, which are parasitic partially or completely on the host tree e.g. striga and loranthus, in mango.

Objectives

1. To study the weeds and its control.
2. To study the herbicides, their types, timing and methods of application.

Weed: A wild plant growing where it is not wanted and in competition with cultivated plants.

Or

Weed is such undesirable plant grown in association with crop which snatches major parts of nutrients, water, light, place and CO₂ available to the crop.

Due to tough competition crop suffers adversely and the production is reduced.

Weed

Weed in orchards reduce crop yields by competing for moisture, nutrients, light and space. They also harbour insect pests and diseases. When they become large they interfere with orchard operations. Some of weeds climb on the trees and shade the foliage. There are some weeds which are parasitic partially or completely on the host tree e.g. Striga and loranthes on mango.

Different crops are grown in a field. Any plant growing in a place where it is not desired competing with the main crops, has to be weeded out and such plants are called ‘weed’.

Effect of weed menace The weeds

Reduce crop yield and production efficiency. It competes with the main economical crop for space, water and nutrients.

Reduce crop quality.

Hamper intercultural operations.

Reduce crop quality.

Obstruct the flow of water in the irrigation channels.

Exert allelopathic effect on crops.

Harbour insect and pests, which affect the main crop of interest.

Increase the cost of production.

Introduction

In a research laboratory, we frequently need weigh chemicals and prepare different solutions of varying strength, as per the requirements. Accuracy in weighing and preparation of solution, with respect to weight/volume and strength, determines the success of experiment. In turn, the accuracy depends on weighing of solid chemical and/or measuring the volume of liquid chemical/making up the volume. In this Chapter, weighing of chemicals using appropriate weighing balance, preparation of solutions of different strength, their dilution, and precautions while preparing will be discuss in brief.

Weighing of Chemical

The primary method to determine the amount of chemicals to be used is weighing the chemical by using a balance.

In general, there are two types of balances to weigh chemicals in a laboratory:

1. Standard laboratory balance

2. Analytical balance

Standard Laboratory Balance

Generally, a standard laboratory balance is used for weighing a chemical when an error of ±0.02 g is acceptable. It is also used for pre-weighing, where approximate mass needs to be determined. Precise mass of the chemical is then determined using an analytical balance. Following are the steps in using a weighing balance in a laboratory.

Rust
The rust of wheat has been studied more than any other disease in the world. K.C. Mehta and colleagues conducted exceptional research on the disease in India. There are three recognized wheat rusts. These include Puccinia graminis tritici, which causes black stem rust; Puccinia recondita, which causes brown rust (leaf rust); and P. striiformis, which causes yellow rust. Considering their later seasonal arrival, brown and yellow rusts inflict more damages than black rust.
1. Black or Stem Rust
Diagnostic Symptoms
• Symptoms are produced on almost all aerial parts of the wheat plant but are most common on stem, leaf sheaths.
• Brown pustules of uredina appear on lower surface of the leaves, leaf sheaths and the stems, and on the spikes. which give them a rusty appearance.
• Uredina form urediniospores , which are the repeating spores.
• Uredina gradually start producing teliospores and finally transform into telia.

Loose smut of wheat occurs worldwide but is more abundant and serious in humid and sub – humid regions. In India, this disease is found in all wheat growing areas but the incidence is generally more in comparatively cooler and moist parts of north India than south India. The yield loss may go up to 30% due to this disease.

Scientific name: Ammi majus L.
Family: Apiaceae
Ammi majus L., a member of the Apiaceae family, is a valuable medicinal plant. Its botanical name is derived from the Greek words "Ammi" and "majus," meaning "sand" and "larger," respectively. This plant has been used for centuries in traditional medicine, particularly for its antispasmodic and anti-inflammatory properties.
Origin and distribution
Ammi majus L. is native to Egypt and is now cultivated in various parts of the world, including India, Europe, and North Africa. It has been introduced to many countries for its medicinal and ornamental value.
Botany
This herbaceous annual plant grows up to a height of 0.75 to 1.15 meters. It has a round, erect, and solid stem with a tap root system. The large leaves are 5-8 cm long, alternate, and light green, with a compound, pinnately divided, and lanceolate shape.
The inflorescence is an umbel, axillary, and terminal in position, bearing white flowers. The calyx tube is adnate to bracts, with 5 teeth. The petals are 5 in number, epigynous, distinct, and bifid. There are 5 stamens, epigynous, and alternate with petals. The ovary is inferior, 2-celled, disk epigynous, 2-lobed, with a solitary ovule in each cell. The style has 2 branches, with a minute and capitulate stigma.

Morphological characteristics

It is a moderately deciduous tree with straight trunk and numerous spreading branches, which form large shady crown with whitish grey corky lenticellate bark, exfoliating in thin flakes. It has a clear bole of 6.0-9.0 meter, and a girth 1.5-2.5m. Branchlets and young parts are clothed with fine white mealy pubescence. Leaves are simple, opposite, broadly ovate, cordate, glandular, glabrous above when mature and fulvous-tomentose beneath. It attains its largest dimension in the mixed forests of moist region as in the eastern sub Himalayan track, Assam and elsewhere in south India.

Floral characteristics

Flowers are 2.5-5.0 cm in diameter, brownish yellow that ends in terminal panicle. Calyx is campanulate, pubescent outside and with 5 lobes. Corolla is showy, brownish yellow with short tube and oblique limbs. Stamens are 4 in number and didynamous. Ovary is 4 chambered with one ovule each; style slender ending in a bifid stigma. Fruits are drupe and obovoid in shape, 1.8-2.5 cm long, pericarp leathery, shining yellow outside when dry; endocarp bony, embedded in an aromatic sweetish pulp. Seeds are 1 or 2, hard and oblong ex-albuminous. The panicles of flowers appear from February to April.

Distribution

Though it is a native of Asia, it has extensively been planted in tropical areas of Africa, Asia, Australia, America, West Indies, and on several islands in Pacific Ocean. In India, it is naturally distributed in Eastern SubHimalayan tract, Aravali Hills, Western Peninsula, Indo-Gangetic plains, Western Himalaya and Central India. It occurs naturally from 5° to 30°N longitude and between 50 to 1300 m elevations.

Curcuma zedoaria (zedoary or white turmeric) is a perennial herb and member of the genus Curcuma, family Zingiberaceae. The plant is native to South Asia and Southeast Asia but is now naturalized in other places including the US state of Florida. Zedoary was one of the ancient food plants of the Austronesian peoples. They were spread during prehistoric times to the Pacific Islands and Madagascar during the Austronesian expansion. Its use as a spice in the West today is extremely rare, having been replaced by ginger, and to a lesser extent, yellow turmeric. Curcuma Zedoaria (Berg.) Rosc.syn. C. zerumbet Roxb; Amomum zedoaria Christm., the Kasthurimanjal of commerce, is also known as Round zedoary in English, Kachura in Sanskrit and Kakhur in Hindi.

Morphological characteristics

Zedoary is a rhizomatous annual or biennial herb with a long, scented stem. It stands at 1.8 metres tall. On the inside, the rhizomes are large and pale yellow or yellowish. The roots are fragrant, and the tubers are ellipsoid in shape. With the exception of a bitter aftertaste, the edible root of the zedoary has a white interior and a mango-like scent; however, its flavour is more similar to ginger. Although there is no obvious aerial stem, the shoot has a pseudo stem made up of four to six long and densely overlapping sheathing leaf bases. The leaves are enormous, up to 1 m long, rectangular and strongly veined, and frequently violet in colour in the centre.

White yams are food plants belonging to genus Dioscorea and family Dioscoreaceae with about 600 species. White yams are among the 10 species of edible yam and belong to species rotundata (D. rotundata Poir). It originated in West Africa.

White yams are herbaceous annual climbers. Its vine arises from large underground stem that is technically called tuber rather than root (Armstrong, 1996). The underground stem thickens to produce one or more tubers which vary in size and shape. The plant bears green flowers that turn brown on maturity and when dry. The aerial stem may be smooth or thorny which could be round/cylindrical (O’ Hair, 1984). Vines can grow to sizeable lengths if provided with a rigid support. Vine length varies within and among species. The leaves could be alternate or opposite, usually heart shaped and may be smooth or hairy. In some varieties, bulbils are formed but this is real in white yam.

Whooping cough is highly infectious specific disease, commonly of children characterized by respiratory catarrh and a special type of cough with inspiratory laryngeal spasm producing a characteristic sound.

This is common in children below 6 years, females are attacked more. Atypical cases are sometimes seen in adolescents and adults.

The disease occurs sporadically and less commonly in epidemics. It occurs mostly in winters and spring and is more common in temperate areas. The causative organism is Haemophillus pertusis present in the upper respiratory tract, conveyed by the infected sputum droplets of the patient to the contacts during the earlier stages of catarrh and paroxysmal cough.

The incubation period is 7 to 15 days or more.

A moderate degree of laryngeal, tracheal and bronchial catarrh with peribroncholitis and acute localized emphysema of the lungs are often associated. The tracheobronchial glands are sometimes enlarged. Rarely the right heart may be dilated and there may be haemorrhage in the brain and the meninges.

24.1 Introduction

When crosses are made between two different species of a genus or between two different genera, they are known as distant hybridization (also called wide hybridization). It includes both interspecific and intergeneric hybridization. Thomas Fairchild (1717) was the first man to do distant hybridization. He produced a hybrid between two species of Dianthus, viz., D. caryophyllus and D. barbatus (Carnation and Sweet William). Intergeneric hybrid produced by Karpechenko, a Russian scientist, in 1928 is Raphanobarssica. It is the amphidiploid of cross between radish (Raphanus sativus) and cabbage (Brassica oleracea var. capitata). Unfortunately, it had roots like cabbage and leaves like radish. Triticale was produced by Rimpau in 1890 itself. It is an amphidiploid obtained from a cross between wheat and rye (Triticum and Secale). Another example is Saccharum nobilisation involving Saccharum officinarum, S. barberi, S. sinensis, S. spontaneum. Wide hybridization has been used in the genetic improvement of some crops. It is an effective means of transferring desirable genes into cultivated plants from related species and genera.

Introduction
Wild marigold (Tagetes minuta) is also famous as African marigold and mint marigold, valued for its higher content and superior in essential oil quality among all the cultivated species undergenusTagetes. Marigold/Genda (Tagetes species) are mostly grown for scented flowers for utilization in functions all over the world. The flowers and leaves are of different varieties, which are identified by their distinct odouriferous oil.
Origin
It is inhabitant to the grasslands of temperate region in South America and now become widespread throughout the world. In India, it has been customized in the North-West Himalayas up-to an altitudes ranging from1000-2500 meters in H.P., U.P. and J&K. Now-a-days, Tagetes minuta is considered as an extensive weed in South Europe, Africa, South Asia, Australia, and Madagascar (Chalchat et al., 1995). It is found growing naturally as a noxious
weed in the wild and arable farming systems. The high demand of its essential oil may leads into reduction of the wild resources, thus it is essential to start systematic cultivation in sub-tropical to temperate agro-climatic zones all over the world, mainly in the region of Indian subcontinent (Singh et al., 2003).

Edible legumes are excellent sources of dietary protein and oils. Winged bean, otherwise known as Goa bean, Manila bean, princess pea, asparagus pea or four angled bean is becoming popular as a tropical legume vegetable. It is a multivitamin and multimineral packed legume. This wonder vegetable was considered as the vegetable of the twentieth century. It is also known as ‘soya’s rival’ or ‘God sent vegetable’. All parts of the plant are edible namely leaves, flowers, immature pods, immature seeds, mature seeds and tubers. It is also named as ‘a supermarket on a stalk’ because the plant combines the desirable characteristics of common bean, pea, spinach, mushroom, soya bean and potato. Its vernacular names are:  Bengali, Chara-koni-sem or lakar-sem; Tamil, Morisuavarai; Kannada, Shambe kayi; Malayalam, Chaturapayar or irachipayar and Marathi, Chavdhari ghevda.

ABSTRACT

Herbal systems of medicine have been acceded by various drug regulatory authorities across the globe. In modern days, people prefer herbal medicines for the cure of various gentle to extreme and chronic disease, and another option is of allopathic system of medicine. In the present communication, the herbal formulations utilize extracted constituents of the various parts of Withania somnifera (L.) Dunal, a member of the famly Solanaceae, and commonly known as Ashwagandha, Indian ginseng, Asgand or winter cherry. This is a principal medicinal plant that has been used in various Ayurvedic formulations from more than 3000 years. Wide distribuion of this species have been reported from the various Indian states like are Gujarat, Madhya Pradesh, Maharashtra, Rajasthan, Uttar Pradesh, Punjab and mountainous regions of Himachal Pradesh and Jammu. This plant is commonly used, either alone or in combination, with other herbs for the cure of various conditions e.g stress and inflammation. The major phytochemicals of this species are alkaloids and steroidal lactones, and due to presence of various bioactive compounds, this plant species possess various multitudinous biological activities such as adaptogenic, antibiotic, aboritifacient, aphrodisiac, astringent, anti-inflammatory, diuretic, sedative, deobstruent, anti-stress, anti-oxidant, anti-carcinogenic, anti-aging, cardio protective, hypothyroid activity, immunomodulatory. Keeping these aspects into consideration, this herb has enormous potential for the management of a number of diseases. In the market, W. somnifera is available in various forms including decoctions, infusions, ointments, powder, tablet, capsule and syrup. This communication provides an account of various chemical constituents and their associated various biological functions.

Wood apple (Feronia limonia (L) Swingle) is a thorny tree commonly found in dry deciduous forests. In India, it is known by several common names like elephant apple, curd apple, monkey fruit, kavat, curd fruit and kath bel. In Malaysia, it is known as gelinggai or belinggai; in Thailand, ma-khwit; in Cambodia, kramsang; in Laos, ma-fit; in French, pommed’ elephant, pomme de bois or citron des mois. The tree is very hardy and has tolerance to drought and salinity. Its cultivation as a fruit tree is rare, but fruits of naturally occurring trees in community lands, forests and on roadsides are  used for chutney and pickle making. Fruits being rich in pectin, minerals and vitamins offer unique opportunity to utilize them extensively for processing. Extensive root system and synchronization of its reproductive phase with high moisture availability make it a suitable crop for arid zones.

Origin and Distribution
The wood-apple is native and common in  wild in dry plains of India and SriLanka and cultivated along roads and edges of fields and occasionally in orchards. It is also grown throughout Southeast Asia, in Northern Malaysia and on Penang Island. In India, the fruit was traditionally a “poor man’s food” until processing techniques were developed in the mid-1950’s. It is one of the very hardy trees  growing all over the plains of India, especially in the semi-arid and arid regions. It is more common in Deccan, Maharashtra, Madhya Pradesh, Uttar Pradesh, Chhatishgarh, Bihar and Jharkhand. Iit also occurs in the Western Himalayas upto an elevation of about 500 m amol.

ABSTRACT

Traditional herbal drug preparations are known for centuries to protect several human diseases such as peptic ulcer, diarrhea, piles and dysentery. Current days knowledge about the underlying biochemical mechanism for most of the gastric ulcers and majority of the duodenal ulcers deserve appropriate consideration and due weightage while consolidating regarding the efficacy of a plant extract. The present investgation relates to a pharmaceutical composition comprising an effective amount of lyophilized extract or at least one bioactive fraction obtained from flowers of Woodfordia fruticosa (L.) Kurz, along with one or more pharmaceutically acceptable additives or carriers. The present results provides a composition for treating ulcers such as stress induced ulcer, peptic ulcer, cold restraint induced ulcer, drug induced ulcer and acid induced ulcer, and also the composition used as specific inhibitor of gastric H+, K+-ATPase. Herbal formulation in the form of capsules were conducted on marker-based stability studies as per ICH Q1 guidelines at accelerated and real time stability studies (40±2°C, 75% ± 5% RH and 30±2°C, 65%±5% RH, respectively), and also stability testing investigation was done as per stability specifications at intervals of 0, 3, 6 months for accelerated stability studies and 0, 3, 6, 9, 12, 18, 24, 36 months for real time stability. The present data reveals that this species is one of the potent Indian medicinal Plant which helps in curing ulcer and associated diseases.

ABSTRACT

Medicinal plants are known to contain innumerable bioactive compounds that play an important role in conventional as well as western medicine. These bioactive molecules occur in plants as secondary metabolites, which have pharmacological relevance and aid in defense mechanism. In India, herbal medicines have been the basis of treatment and cure for various diseases. Conventionally, natural products have been tested as crude extracts containing complex mixtures of compounds, which if showing a desired activity, require a process of purification and identification of the active components, which can be lengthy and efficient.

In order to understand the function of these active compounds, X-ray crystallographic studies are carried out.

The present study involves the three dimensional structure analysis of purified compounds from the plants Phyllanthus amarus, Sphaeranthus indicus, Scoparia dulcis and Mangifera indica and Leonotis nepetaefolia.

Yam bean (Pachyrhizus erosus) is a leguminous tuber crop of immense production potential. The crop has high rate of dry matter production / day / unit area and is known for its high degree of photosynthetic efficiency. Besides contributing significantly as a source of food to  weaker sections, the crop has immense industrial value for extraction of starch and production of animal feed. Yam bean is well suited to small and marginal holdings and has the capacity to withstand adverse biotic and abiotic stresses. It comes up well in comparatively marginal lands and does not require intensive care. It has  great potential in developing and underdeveloped countries where most of the farmers are small and marginal . This crop is very important in the context of food and nutrition security and assumes great significance due to ever-increasing human population. Still the importance of this crop is underestimated and unlike most staples, the crop fails to attract attention of  agricultural researchers throughout the tropical and subtropical countries of the world. The crop is still largely under-exploited and is subjected to little selection pressure. A large degree of variability exists for several agronomic characteristics in the existing germplasm. With a little attention from the scientists ,this crop could usefully be exploited by genetic improvement and development of crop ideotypes which would meet a wide range of needs in developing countries.

Yam bean(Pachyrrhizus erosus), a leguminous crop, native of North America is cultivated for its edible tubers. Though six species of Pachyrrhizus are grown for tuberous roots, P. erosus, P. tuberosus and P. aphipa are important.

While P. erosus(L.) Urban(2n = 22) has pods of 7.5-13 cm long, P. tuberosus has longer pods of 13-30 cm. P. aphipa is a non climbing plant with fusiform tubers and this species is mainly cultivated in Bolivia.  Synonyms for P. erosus are P. angulatus, P. bulbosus and Dolichus erosus.  P. erosus is the species commercially cultivated in India.

Wild forms of yam bean are seen in Mexico and northern parts of Central America, where its cultivation is reported during pre-Coloumbus period.  Yam bean is believed to have spread from Mexico to Philippines, Amboina before 17th century.  Now, yam bean is cultivated in China, Thailand, Singapore, India and Hawaii.

In India, it is grown in Bihar, West Bengal and Orissa.  In Hindi, it is called as “Miskri kand” and in Bihar as “Kesaru”.

ABSTRACT

Zanthoxylum armatum DC. is a plant species belonging to flowering family Rutaceae which has medicinal application in traditional Ayurvedic system of medicine. It is characterized by trifoliolate leaves with leaf-stalk winged, branches with straight prickles, and fruits are small reddish brown. In India, tribal community used this species as carminative, dyspepsia, tooth curing, treating malaria fever, stomach pain and expelling roundworms. Chemistry indicates that Z. armatum is a repository of many chemical compounds such as alkaloids, flavonoids, sterols and triterpenoids. Zanthonitrile, berberine, α-sitosterol, armatamide, limonene and linalool are major constituents. Leaves and young shoots yield essential oils which act as anti-bacterial, antifungal and anthelminthics, and has tremendous potential in development of value added products. Volatile oils are active constituentsof linalool, limonene and ligan. Z. armatum has been declared as an endangered species as per International Union for Conservation of Nature and Natural Resources(IUCN) Red List category. Conservation practices needs to be adopted to conserve this valuable medicinal plant. There is a need to study on ecology, adaptive biology, chemistry and biotechnological intervention for future propagation and conservation of this medicinal plant species.