Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5847_Библиотеки_им_академика_М_И_Перельмана

during plantation and are mostly expensive, irrespective of their high productivity. Cuttings have length under 80cm are best managed as nursery plants before their transfer to land. Cuttings may be directly planted on top of growth substrate and mulch prepared from different sources, before the healing of cut sites. The top of the longer cuttings may be attached/tied to a support and make sure that at least 1–2 nodes are in contact with the substrates. Similarly, leaves that are in contact with substrate, must be removed from nodes [22]. Moreover, tissue culture V. planifolia Jacks. ex. Andrews plants are also available from selected stores/companies in vari­ous countries. No doubt, tissue culture plants are very much appealing as a clean source of starting material, but it will take 3 or 4years to mature enough to ower [23]. Vanilla is not usually cultivated by seeds because of germination challenges. The lignied thick seed cover inhibits germination as well as its seed also take con­siderably longer time to grow into a young and mature plant as compared to cut­tings. Similarly, seed germination tends to associate with fungi and with another microorganisms. Such type of constraints has played a critical role to use cuttings as the primary propagation method [16].

In Asian regions, particularly in Pakistan, the best season is July and August when irrigation lands can be used more freely, except beyond the favourable tempera­tures [7].

Humus is the primary source of nutrition for vanilla plant that results from decom­position of organic matter by bacteria, microorganisms, and worms. It consists of plants and animals’ residues i.e., mulch. Using mulch has various advantages. It keeps the humidity of soil maintained. Mulch keeps the soil aerated and does not hinder the growth of roots. Maintained temperature is available and growth of weed is inhibited. Decaying leaf mulch is best for vanilla growth. Mulch should be placed 10–20cm deep on both sides of the root. New mulch is added 2–3 times a year [22, 26].

Developing a composting system is a useful method to full the nutritional require­ments of vanilla plant. There are several ways of making compost but the best one is to use pine sawdust and sheep manure. Vanilla plants grow on orange tree sup- ports. By mixing 70%-line sawdust and 30% sheep manure, compost could be made. For moisture purpose, 40–65% water is applied to it. The compost should be covered with plastic to protect it from rain. The temperature should not be more than 65°C. For aeration and decomposition, the compost should be mixed after each 15days. In 3months, the compost gets ready for use. At this point it should contain 30% moisture. It is applied one to two times each year, after which the growers irrigate immediately so that maximum absorption of nutrients take place [10, 18].

In vainillales, shade is controlled by pruning of support trees such as Erythrina sp. Usually 2–3 times a year. Pruning should be done in rainy season i.e., July to November to prevent disease development in vanilla. During rainy season, shade is around 30–50%. In dry season, the canopy of support trees is dense that provides 70–80% shade. This protects the vanilla plant from burning and early fruit drop. When orange trees act as support trees, young buds are also pruned that obstructs the growth of vanilla [19, 27].

pollinators of vanilla. Hummingbirds (Cynniris sp.), bees (Melipona beechii), and bats are considered natural pollinator for a long time. The most popular hypothesis accept that common pollinator is Euglossa viridissima, a shiny green orchid bee [35, 36]. Moreover, these bees have been observed visiting the owers irregularly and their effect on pollination is too small, approximately just 1 fruit per 100 or 1000 owers [35, 37]. Furthermore, only single fruit is normally observed per raceme with natural pollination. A few orchid insects, namely, individuals of Eulaema sp. (jicotes) occasionally visit the owers of Vanilla sp in northern Veracruz, Mexico. Rarely, they may also pollinate the owers upto 5% while search­ing for nectar along the base of the labellum. The mechanism through which above mentioned bees originally pollinate the vanilla owers is not determined yet [6].

Normally, 6–8 owers per inorescence must be pollinated to produce at least 4–5 fruits of good quality (pollination is not always 100% successful). There is need of at least 8–5 pollinated owers per inorescence to obtain 100–120 fruits per plant. No doubt, these estimations are rough because much depends on the position of ower, vigour of the plants, and environmental conditions as well as the biological traits of selected cultivar.

Moreover, vanilla producers also estimate the number of owers to be pollinated by observing both market demand and pricing because over-pollination causes abundance of smaller fruits of less economic value. Similarly, it also increases the labour cost of pollination of inorescence. Over-pollination also causes major vari­ations in crop volume from year to year [34].

The curing of vanilla is done to produce an aromatically attractive and microbio­logically resistant product from dark green pods harvested just before complete ripeness. Before curing it has no special aroma apart from a vague plant odor. The curing techniques are of broad range and may vary from region to region, but gener­ally complete in four separate stages.

In the second step, the heat stored during the initial step is maintained, if possi­ble, by keeping the pods in closed wooden boxes that are used as heat insulator. This step is called “sweating”. Some authors [41] report that during the second step the pods may release a blackish uid due to drying and sweating of pods [6, 42]. The blackish uid is released due to excess condensation.

The initial heat cures and initiate the aroma development in vanilla, that is a ongoing process till the completion of curing. The breakdown of various glycosylated pre­cursors is the most recognized phase in the improvement of the aromatic excellence of vanilla. However, it is worth noting that several aromatic chemicals, such as p­hydroxybenzoic, p-hydroxybenzaldehyde, Acid, vanillin, vanillic acid, etc. are pres­ent in green vanilla pods in glucoside type and their breakdown is necessary to make them enable to release fragrance or aroma [6].

Viruses are obligatory cellular parasites that infect all the living organisms. They have most likely appeared and evolved in their hosts along the emergence of tree life [53]. Viral diseases are one of the major hurdles in increasing the vanilla production since few decades probably due to diversity in crop elds and intensied cultivation [6]. There are more than 20 virus species that infect orchids [54] and Wilser was the rst person to demonstrate vanilla viral infection in French Polynesia. Sometimes, it is much difcult to identify the infected plants because some plants do not exhibit clear symptoms or are asymptomatic [55]. Currently, 10 positive-sense RNA viral species belonging to four families are reported to infect vanilla. Cucumber Mosaic Virus (CMV), Cymbidium Mosaic Virus (CymMV), Odontoglossum Ringspot Virus (ORVV) and Potyviruses are the most common viruses that infect vanilla crop. However, viruses have great ability to evolve faster and the emergence of new viral strains in vanilla elds are likely to occur probably due to speedy environmen­tal mutations caused by climate change [56, 57].