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

Flowering in Tagetes minuta L. takes place in the month of September. Crop har- vesting is carried out from October till November when the crops fully bloom. At the end of November, seed harvesting is done. It is recommended to remove apical meristem during the mid of month of August, which will check the growth and pro­duction of lateral branches [14].

Propagation by seed can be done by two methods i.e., direct sowing and transplanta­tion of plants.

2. Transplantation Preferable time for the transplantation of plant in main eld is from the month

The owering period of plant is February, June and November (Table 13.1). Whereas, fruiting can take place three times during a year that are from December to January, March to April and July to September [18] (Fig.13.3).

invitro propagation techniques have been opted. In research conducted by Mohamed etal. (1998) the cotyledons and hypocotyls of Tagetes minuta L. were cultured on MS medium containing IAA or NAA and BA.Adventitious shoots developed from the hypocotyl-derived callus. However, these adventitious shoots failed to generate further. Contrarily, cotyledon-derived callus cultured on MS medium containing IAA generated adventitious shoots which later developed into plantlets. Highest number of shoots were obtained by culturing cotyledons initially on medium con­taining 71μM IAA+44.4μM BA and later transferring them to MS medium. From the developing shoots nodal segments were taken which were micro- propagated on half-strength MS medium containing 2.58 μM IAA. 95% of plantlets developed from these nodal segments successfully adapted to greenhouse conditions. The plantlets produced from invitro culturing of nodes had many shoots whereas those micropropagated from shoot tips consisted of a single main stem. Morphological differences were studied after 2months growth in greenhouse. However, no signi­cant difference was noticed in dry weight of leaf and shoot. After six times subcul­turing of cotyledons-derived callus on medium containing IAA and BA all explants lost their regeneration capacity except those growing on 17.23μM IAA and 44.4μM BA.This research developed a novel protocol for shoot regeneration from cotyle­dons of Tagetes minuta L [25].

Wild marigold because of their highly avored and fragrant essential oil are in great demand by industries. They can be grown in wide range of climates but due to changing climatic conditions their growth is now becoming restricted as a result of different abiotic stresses. These abiotic stresses at elevated level results in reduced germination, growth and low quality essential oil. Wild marigold is vulnerable to following abiotic stresses.

and mesophyll conductance in limited water availability [30]. In drought stress sto­mata while acclimatizing to their environment varies in their anatomical features such as size and density. This affects the transpiration rate in wild marigold. Reduction in growth of Tagetes minuta L due to drought is the result of formation of ROS in cellular compartments of chloroplast, peroxisomes and mitochondria [31]. Due to accumulation of ROS in plants, degradation of membranes starts. Photosynthetic activity also reduces due to these ROS.To survive in water stress conditions wild marigold increases its root biomass and length, reduces growth of its shoot and alters leaf orientation to minimize the loss of water. Severe drought conditions prevents wild marigold from absorbing Photosynthetically Active Radiations (PAR) thus preventing it from accumulating dry matter. It is suggested that root traits should be thoroughly studied to make the crop drought tolerant. In response to dehydration abscisic acid (ABA) activates. It protects the plant by clos­ing stomata, reducing leaf size and promoting root elongation [32].

selection strategy in natural populations of wild marigold under waterlogged condi­tions is necessary. Under oxygen stressed conditions ethylene production changes the tolerance mechanism in plants by expression of certain genes which induces formation of aerenchyma. However, much literature is not available on oxidative stress due to waterlogging in wild marigold.

Heavy Metal Stress in Wild Marigold Because Wild marigold produces essential oil thus it can accumulate heavy metals. These can extract harmful heavy metals from the environment together with providing economic benets to the growers. Wild Marigold accumulates lead (Pb) from the atmosphere thus they can be employed for phytoextraction of lead. In an experiment conducted by Sosa etal. (2016) wild marigolds growing at ve different sites were observed. These sites were Pb contaminated as they contained former battery plants. It was found that despite of wild marigolds growing in lead contaminated soil with their leaves accu­mulated with lead, their essential oil didn’t contain any traces of lead [39].

In this disease, collar portions of the plants are affected by fungus (Sclerotiana scle­rotium). The infection results in damping-off and aggravation. As the result of infec-

Flower Bud Rot is caused by Alternaria dianthi. Young ower buds are susceptible to attack. The infected buds appear dark brown in color. The pathogen also infects leaves, causing blight in them. On margins and tips of older leaves, brown necrotic spots can be seen. Bud and leaf infections can be control by Mancozeb spray [23].