Common flora used traditionally in agriculture ecosystem

 Common flora used traditionally in agriculture ecosystem

One of most common and important plant used in agricultural operations is Neem (Azadirachta indica). The properties of Neem as insecticide, antifeedant, hormonal, antifungal, antiviral and nematicide properties are well known. These activities are brought out with neem use in the form of leaves, leaf extracts, seeds, cakes, oil and fruit extracts (Lokanadhanet al., 2012). This plant control about 200 species of insects i.e. Aphids, leaf miners, looper, thrips, mealy bugs etc. It kills all chewing and sucking insects, also disrupts their life cycle and sexual behavior (Kaur and Ohri, 2018). Azadirachtin, salannin, and other limonoids present in neem oil inhibit ecdysone 20-monooxygenase, the enzyme responsible for catalyzing the final step in conversion of ecdysone to the active hormone, 20-hydroxyecdysone, which controls the insect metamorphosis process (Campos et al., 2016). In addition to that the neem seed cake also contains nitrogen (2-5%), phosphorus (0.5-1.0%), potassium (1-2%), calcium (0.5-3%), magnesium (0.3-1%), Sulphur (0.2%-3.0%), Zinc (15 ppm-60 ppm), Copper (4ppm-20ppm), Iron (500ppm-1200ppm), Manganese (20ppm-60ppm) in pure organic form (Eifediyi et al., 2017).

Several plants which are used frequently in Hindu rituals like members of Ocimum and Aegle marmelos are known to possess metabolites having agricultural significance like antifungal and insecticidal properties and other important bioactivities. Ocimum kilim and scharicum known as camphor basil possess insecticidal property against Helicoverpa armigera (Singh et al., 2014). Leaf extract of another common Tulsi (Ocimum sanctum L.) was observed to have insecticidal property against Pulse beetle (Callosobruchus chinensis L.) in stored green gram (Murasing et al., 2017). Leaf extracts of Ocimum sanctum was also found to have anti plant pathogenic effect against Alternaria solani causal organism (c.o.) of early blight disease on tomato plants, Rhizoctonia solani c.o. of sheath blight of rice, etc. (Dheeba et al., 2014). Many other plants also inhibited mycelial growth and sclerotial formation in Rhizoctonia solanisuch as Allamanda cathertica, Lawsonia alba, Duranta plumeiri, etc. Clove extract completely inhibited the growth of R. solani, R. oryzae, R. oryzae-sativae and Sclerotium hydrophilum. Siam weed extract was found to be effective in reducing severity of blast, brown spot and bacterial leaf blight disease of rice (Islam and Monjil 2016). Number of studies have proved all plant parts i.e. leaves, bark and fruits of Aegle marmelos (Bel) to have fungitoxic and fungicidal effect on many agricultural pathogens like Rhizoctonia solani, R. bataticola, Colletotrichum gloeosporioides, Fusarium oxysporum f.sp. pallidorosem, F. oxysporum f.sp. ciceri, Phomasorghina, Sclerotium rolfsii, Sclerotinia sclerotiorum, Alternaria solani and A. alternate (Kushwah 2013).

Extracts of various parts of common plants like Pyllanthus emblica and Syzygium cumini could impart up to 90% Larvicidal and antifeedant activity against agriculturally important pests like Plutellaxyl ostella which could cause 90% crop loss in crucifers (Riat and Ohri, 2018). Similarly, antifeedant, larvicidal, pupicidal and biochemical effectsof extracts of Solanum xanthocarpum were observed against Helicoverpa armigera, a pest which causes about 40% or more yield loss of vegetables and other crops such as tomato, pigeon pea, rice, chick pea, cow pea, sorghum, alfa alfa and tobacco (Baskar et al., 2018). In addition to their medicinal and therapeutic use, plants like Adhatoda vasica, Acorus calamus and Vitex nugendo also act as a source of phago-antifeedant against cabbage butterfly Pieris brassicae and cabbage aphid Brevicorynebrassicae (Bajpai and Chandel, 2009; Haifa and Ali, 2016).Similarly, ethanolic extract of Thymus vulgaris plant showed 98% of mortality rate towards tomato pest Tuta absoluta where LD90 value was 89383mg/l (Nilahyaneet al., 2012). Plant extracts of Rhododendron luteum was proved to affect the fecundity rate of Tetranychus urticae, a pest of ornamentals and vegetables (Cazaux, et al., 2014). Very common plants are also used to control storage insects which are great threats to stored agricultural products in many countries. wild and cultivated Rosemary (Rosmarinus officinalis) has useful chemical constituents like L-camphor, L-borneol, 1, 8-Cineole and boranyl acetate which were proven to have insecticidal properties against storage peat Trogoderm granarium and Tribolium castaneum (Alvarozet al., 2016). Similarly, plants like Peganum harmala, Aristoelochia baetica, Ajugavia and Raphanus raphanistrum exhibited deleterious toxic effectives against both larvae and adult of Tribolium castaneum, stored grain pest (Riat and Ohri, 2018).

As discussed earlier in this section, many of the botanicals might have less effect than synthetic pesticides but unlike some common plants like Bidenspilosa, Lantana camara, Lippia javanica, Tephrosia vogelii, Tithonia diversifolia, and Vernonia amygdalina, the beneficial and non-target flora and fauna are less disturbed simultaneously enhancing the crop yield. This is most notable with the use of T. vogeliiin Tanzania where the yields were statistically comparable for cowpea (1,016–1,125 kg/ha) and pigeon pea (4,407-4,464kg/ha) and where the bean yield was statistically higher for T. vogelii compared to the positive control (2,044 vs. 1,659kg/ha) (Temboet al., 2018).