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Agriculture

Gender Issues in Plants

Female Guduchi outperforms

Most flowers have both male and female parts. In some species of plant, male and female flowers are distinct and, in yet others, the individual plant may produce only male or only female flowers. In plants such as the papaya, where male and female plants are separate, only one male plant is required in a whole field of female plants. However, farmers cannot know which is male and which female, until flowering. If only farmers could tell earlier, many male plants could be removed and the space used for other productive crops. How does one differentiate between the genders when there are no flowers?

Tinospora_cordifolia

Image: Tmd via Wikimedia Commons

A team from CSIR-Central Drug Research Institute, Lucknow, along with collaborators from NBRI, Lucknow and AcSIR, New Delhi, now reports that male and female plants have distinct phytochemical profiles.

The team selected Tinospora cordifolia (Guduchi), known for its immuno-protective effects. The stem of this medicinal climber is the major raw material in Ayurvedic preparations.  Female stem extracts show higher immuno-modulatory responses in mice. So identifying female plants before they flower can facilitate selective growing of the right gender for use in poly-herbal formulations.

The team selected the stems of male and female plants and developed metabolic fingerprints of the two genders using mass spectrometry.  Then they analysed the chemical profiles of the stems using multivariate and principal component analysis. Using this technique, they could not only identify the gender of the sample, but also its geographical origin.

There are many other plants, besides Tinospora cordifolia, that exhibit sexual dimorphism. Many cucurbits, papaya, and other vegetable and fruit crops can benefit from the same methodology adopted by the scientists at the CSIR-Central Drug Research Institute.

Industrial Crops and Products, 101: 46-53 (2017)

Rekha R Warrier, IFGTB

 

31 January 2018

Predicting Prey and Predators

Population dynamics in fisheries

Not too far below, in the sea, a large number of tuna fish, at the same stage of development, swim together to form interesting patterns – now a whirlpool and now an ellipse that stretches into a line. It is an amazing sight to behold. And a delight for the cod that run in similar tight packs and feed on tuna.

tuna_102948248

Image credit: World Wild Life Fund

This prey predator relationship inside the water makes it difficult for fishermen to anticipate their catch of tuna and cods. And fishery resource managers take action to optimise the harvesting of available resources without jeopardising sustainability.

About 100 years ago, Volterra used equations developed by Lotka to impress his father-in-law who was puzzled by the variations in the magnitude of catches of predatory fish in the Adriatic Sea during World War I. The Lotka Volterra model explains prey predator relationships. Foxes eat rabbits. So the rabbit population goes down. Not having enough prey, the fox population goes down. Now, since the predator population has gone down, rabbits have a hay day and proliferate. Thus the prey-predator populations play yo-yo.

But this model is not really applicable to schools of fish that are prey to human harvesting, say researchers from Kolkata and Howrah. While a fox may eat an unwary rabbit, here it is the case of a school of cods preying on the edges of a school of tuna. Moreover, beyond tuna and cods, there is human exploitation of fish populations. So they have now put forth a more elaborate model that takes these factors into account.

The mathematically minded reader may examine the model and its applicability to sustainable fishery resources management, as well as for forecasting the variations in the amount of different fishes for fishermen.

Appl. Math. Computation, 317: 35-48 (2018)

Nitin and Madhu

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