eChapters

In grape growing areas in many parts of the world this illness is a very popular disorder. In this disorder, a bold beer is surrounded by shoot berries, and the name of the hen and of the chicken disorder is like a hen, as bold berry and chicken. The fruit has a sour taste. The signs are the death of rising tips, falling leaves and the fragility of new shoots. With the development of interveinal chlorosis between the edges, the leaves may be deformed, and this is particularly evident after fruiting.

Bronzing is a complex nutritional condition in guava (Psidium guajava L.). It manifests in the interveinal tissue of older leaves as bronze or copper colour development, while terminal leaves remain green. This is attributable to the inadequacy of elements P, K and Zn. Bad management and low soil fertility coupled with soil acidity are often due to it.

Physiological disorders are abnormalities in plants which are associated to non-pathogenic factors. A plant or its parts may show unusual growth, function or deformity. Such abnormalities are widely referred to as disorders. These may be incited by nutrients deficiency or excess, hormonal imbalance, abnormal growing conditions etc. Some commonly observed disorders have been dealt in here suitably.

Tip-burn is the marginal collapse and necrosis of rapidly spreading inner lettuce leaves, at or near the leaf margins. Typically, the condition occurs near harvest, when it may lead to complete crop failure. Early signs include discoloration of the veins and/or the growth of dark brown to black spots near or at the margins of the leaves. The necrotic areas coalesce as the disease progresses, creating a lesion up to several centimeters long.

Problems are low fruiting / non fruiting / irregular fruiting in the country’s litchi farming area. The potential of bear litchi has been identified as variety, although some of the bearing terminals in the present year will be more active in the next year (70-95 percent).

This is one of the most serious difficulties in mango farming since it makes mango agriculture less rewarding for farmers. In one year (a year) and very little or no harvest next year, mango trees appear to bear huge crops (off year). This bieniality is therefore also present in normal ranges (Singh, 1990). 

When the soil temperature stays at or below 20 0 C, seeds germinate poorly. During early spring-summer planting, this issue of seed germination occurs when seeds are to be sown at low temperature conditions.

Twitching is a condition occurring predominantly on the surface of the fruit which is exposed to direct sunlight; however, it is not well understood what the source of the disease is. Growth in immature fruits cannot be detected during later stages of fruit maturity. On cv. Golden Solo Party there are a few examples. This is termed the “frog skin” or “fox skin.” It shows on the fruit’s surface as the Dark Brown Flecks. 

Ordinarily, fruit bears a single crown, but fruit bears more than one in some cases. The top of the fruit will therefore be smooth and wide and the fruit will not be ideal for canning. These fruits have an insipid taste and are corky. It is intended to be an inherited character, often found in the Cayenne group to which the Kew variety belongs.

Fruit cracking is a serious problem of pomegranate (Punica granatum L.) particularly in arid climate. Cracked fruits are sweet but unfit for long distance transportation. Incidence of cracked fruits varies from 10 to 70 % depending upon the prevailing environmental conditions. Longitudinal or radial splitting of rind surface occurs.

There is secondary elongating growth in the roots that gives a form of fork like structure to the root. This occurs in heavy soil due to soil compactness. An elongated radish root is encouraged by un-decomposed organic manure. It can be fixed by decreasing field moisture, balanced irrigation and also by sowing radish and carrot in sandy loam or light soil with loose and friable soil in nature.

The normal blooming stem on the greenhouse rose has fully developed sepals, petals and reproductive organs. The inability to build a bloom at the apical end of the stem is a typical phenomenon which in such shoots is termed blind. There are sepals and petals; however, they are not complete or aborted in the reproductive portions.

Blossom end rot is a very common problem on green and ripe tomatoes. It started with light tan, water-soaked lesion, and then increased to black and tough. Although blossom blight itself caused only local damage, secondary biological invasions frequently lesions caused fruit rot complete.

Symptoms of pale or yellow-green leaves (chlorosis) first occur in the older leaves. At the leaf margins reaching toward the midrib or central vein, reddish tints gradually emerge. The leaves are thin. Growth overall is markedly reduced. Deficiency results in rhizome yield loss.

In addition to pathogenic diseases, numerous abiotic disorders may also arise during growth, development and post-harvest storage of solanaceous vegetables. The physiological disorders of vegetables that have been included in this chapter are directly or indirectly associated with genetic, cultural, nutritional, physiological and environmental factors, and in most of the cases, the definite cause of disorder is not well understood due to the association of numerous factors together. These disorders may be related to colour, shape and form/condition of the produce. The genesis of physiological maladies was earlier poorly understand due to complexity in their characteristic symptoms but at present is relatively more transparent. The characteristic symptoms of abiotic disorders discussed below have not been attributed solely to a single agent or to a single cultural or environmental factor. The environmental factors correlated with the incidence of these disorders include high light intensities and low or high temperature of that growing area. For many abiotic disorders, very limited research work has been done, and the causes are poorly understood both in terms of why cultivars differ in susceptibility and why certain environmental factors predispose the plants or parts of the plant to the disorder. The growers feel concerned with the incidence of abiotic disorders as these cause huge economic loss. Therefore, the control of these abiotic disorders is essential for profitable production of solanaceous vegetable crops. In this chapter, emphasis has been given on practical aspects of diagnosis and potential control measures.

Harvesting is one of the agronomic management practices that require technical knowledge on maturation of the crops. This knowledge is much important in seed production than in commercial production.

Physiological maturation

• It is the stage of accumulation of maximum dry matter within the seeds. The moisture content of the seed at this stage will be in decreasing order (25-30%) and is expressed with maximum dry weigh of seed, germination and vigour potential. The physiological maturation is represented for individual seed and this maturation will not be the same for the population, due to differential flowering habit.
• The attainment of physiological maturation is represented by sigmoid curve of growth pattern. The physiological maturation can be represented both as duration and visible symptoms.

Most of the plants undergo a period of rest, and in this period, the growth activities temporarily halt. The whole plant looses its aerial parts and undergoes a rest period in the form of rhizome, corm, or tuber. Researchers who study fruit trees use the term rest for dormancy (Samish, 1954). This period is sometimes called as quiescence. The term rest and quiescence can be included under common category dormancy. Some workers differentiate the term dormancy and rest period (Burton, 1964). Wareing and Co-workers (Robinson and Wareing, 1964; Wareing et al., 1964) isolated dormancy inducing substance in sycamore seedlings (Acer pseudoplatanus) which was named as dormin. Further, analysis of this substance by Cornforth et al. (1965) reveals that dormin was identical to Abscisin-II (a substance speeding the abscission of the young flowers of Lupinus luteus and have antiauxin effect).

Dormancy can be defined as an arrest in development of buds, seeds, embryos, or spores under conditions otherwise suited for growth (Taylorson and Hendricks, 1977). It is a survival strategy (exhibited by many plant species), which enables them to survive in climates where part of the year such as winter or dry seasons is unsuitable for growth. The dormancy may be due to the factors within the dormant organ or seed itself and it is called spontaneous dormancy. This type of dormancy is found in seeds, buds and perenating organs like tubers, bulbs, bulbils, corms and rhizomes. In some weeds, dormancy is caused by high or low temperature and this type of dormancy is called as imposed dormancy. Seeds normally germinate in darkness but are inhibited by light are considered to become dormant after exposure to light (Bewley and Black, 1982; 1985). Seeds that require light for germination are said to be photo dormant.

In general terms, dormancy can be defined as a period during the biological cycle of the plant in which growth of the whole organism (seed) or a plant organ (bud, tuber, corm etc.) is suspended eventhough the environmental conditions for growth may be favourable. More specifically, dormancy refers to a condition in which growth is inhibited by a restriction of essential metabolic processes, such as water uptake, gas exchange and cell division, either as a result of endogenous dormancy-controlling factors or in response to exogenous factors such as changes in the environment. It is distinct from a transient state of quiescence or rest imposed by an unfavourable environment in that dormancy persists even when the environment becomes favourable for growth whereas quiescence ceases.

For wild plants, dormancy has evolved as a means of enabling the plant to endure periods of stress due to drought or low temperatures and is therefore critical for the survival of the species. In cultivated arable or vegetable crops, breeding has generally led to a loss of dormancy or a reduction in the length of the dormant period. In arboreal crops of temperate climates, however, bud dormancy is still an essential feature of the annual growth cycle of the tree.

Flowering is the most important phenological event in the phyotogerontology, as it is the key factor contributing to fruit production and profitability to the orchardists. Under favourable growth conditions the timing and intensity of flowering greatly determine the quantum of production. However, several times there are very contrasting florigenic events where despite prolific flowering, resultant fruit set remains low leading to low yields. Therefore understanding of the various external and internal factors involved in flower induction in mango is crucial for developing suitable orchard management practices to achieve regular and high yield.

Growth: Growth involve cell division subsequently cell elongation. Increase in volume that is associated with fruit growth largely result of cell division or cell elongation or both. In some fruit such as apple, extension of intercellular space may also contribute the growth. Generally growth by cell division in early stage whereas, cell elongation during later stage.

Two distinct type of growth curve are observed when increase in such variable such as fresh weight, volume and dry weight of fruit.

1. Single sigmoid curve
2. Double sigmoid curve

In case of single sigmoid growth curve firstly there is rapid increase in size then after decline so there is only one rapid growth is observed e.g. Apple, pear, tomato, cucumber and strawberry.

In case of double sigmoid two rapid growth period are separated by an intermediate period that is less growth or no increasing growth curve. Double sigmoid growth curve can be used as two successive sigmoid curve thus there are three clearly define stage of growth.