Research

A comparative study on blue, green and red light frequencies and the effects on tomato proliferation

The use of photoselective films is fast becoming popular within the horticultural industry. In times of austerity growers and researchers need to be able to manipulate plants to increase production rates and thus profits. A possible solution is to enhance development by using these films. To examine this solution, model species Lycopersicum esculentum ‘Money Maker’ was grown under blue, green and red light to investigate their effects. Under blue and red there were no significant differences in plant development. 

Under green photoselective film plants altered their growth rates resulting in wilted foliage. However, blue light was found to modify the production of fibrous roots. Under red photoselective film, root length was unaffected. On the contrary under green light, roots were significantly reduced. This study demonstrates that photoselective films can be used to manipulate plant growth with a strong response to green irradiance. However more research is required to gain more quantitative data for analysis so that more conclusions can be drawn.

A comparative study on blue, green and red light frequencies and the effects on tomato proliferation - Revisited 

 The use of photoselective films is fast becoming popular within the horticultural industry. In times of austerity growers and researchers need to be able to manipulate plants to increase production rates and thus profits. A possible solution is to enhance development by using these films. To examine this solution, model species Lycopersicum esculentum ‘Money Maker’ was grown under blue, green and red light to investigate their effects. Under green and blue there were no significant differences in plant development. 

Under green photoselective film plants reduced their growth rates resulting in wilted foliage. However, red light was found to modify the production of fibrous roots. Under red photoselective film, root length was increased as well as leaf span. Similarly under blue light leaf span was increased as expected. This study demonstrates that photoselective films can be used to manipulate plant growth with a strong response to red irradiance.

The sustainability of sunflower proliferation under chemiluminescence

The horticultural industry and scientists have investigated millions of pounds in research to understand the processes of photosynthesis and how it could be manipulated to increase its efficiency. A possible low cost solution could be the use of chemiluminescence. This investigation has demonstrated that chemiluminescence could sustain plant growth. 

Thirty-six Helianthus annuus were used for this experiment over a period of 3 months. Under chemiluminescence there was a significant difference in the height of plants when compared to the control by 1.61 cm. When root length and dry weight were compared to the control there was no significant difference. 

When the health of the plants was rated there were no colouration or abnormalities issues. Thus proving that chemiluminescence can sustain plant growth and could even increase it. There is a wide range of practical applications for this discovery such as emergency lighting for nurseries or it could even be used as a source of supplementary lighting. This has been backed up by the findings of another study using cyan light.

Increasing and sustaining the freeze tolerance of three green algae which have the potential for bioremediation in the tertiary stage of wastewater treatment within the UK horticultural industry

In recent years bioremediation has been set to replace the tertiary stage of wastewater treatment as a more sustainable and environmental friendly process. Additionally microalgae in wastewater treatment could be harvested for biofuels. Major species which are the most efficient at water filtration include: Chlorella vulgaris, Scenedesmus subspicatus and Nannochloropsis oculata which are all green microalgae. C. vulgaris is considered the most used and studied species for bioremediation and biofuels.

However, these microalgae have a limitation to their growth as they cannot tolerate subfreezing temperatures. As a possible solution, glycerol was added to a sample of these microalgae to see if it increased their freeze tolerance. A cell count, biovolume and chlorophyll a and phaeophytin a determinations were carried out to verify this hypothesis. In fact the cell count and biovolume of C. vulgaris increased by 96.57% and chlorophyll a content by 72.90% when subjected to temperatures from 0 to -10ºC. 

When compared with Chlamydomonas nivalis, a type of ice algae, the algae had a 2.09% decrease in yield; nevertheless they are not adapted to survive at temperatures as low as -10ºC. This new technique could enhance sustainable methods of wastewater treatment within the UK horticulture industry.

Examining the water filtration of duckweed for use as a source of wastewater treatment for the domestic sector

Lemna major (duckweed) has been identified by several major papers within the field of bioremediation as a promising means of water filtration. This simple free-floating plant has attracted the attention of governments around the world who have heavily invested in this new avenue of research as a possible means of grey-water reconditioning. 

It has also become a future source of domestic wastewater treatment as an environmentally friendly process. To test the ability of Lemna major to treat domestic grey-water three different concentrations were used: 40%, 60% and 80% as well as a control. It has been demonstrated that L. major can remove 74% of nitrogen and 77% of phosphorous from a 100 m2 sewage lagoon within a 21 day period. As a plant for wastewater treatment, Lemna major has several advantages over other macrophytes and microphytes. Lemna produces 50% more 02, capturing 40% more C02 as other studied genus and has a high rate of NH4+ uptake. NH4+ as waste organic source of nitrogen can encourage excess blooms of microalgae and phytoplankton resulting in eutrophication. 

The results of this experiment demonstrated L. major’s ability to process grey-water. The different concentrations showed a similar progression compared to the control however, the 80% concentration decreased in turbidity by 95.50%, leaf count only increased by 0.04%, biomass increased by 3.70% and finally water pH was an 8.05% increase when compared with the control, thus demonstrating the filtration capacity of L. major.

Examining the root penetration rate of peat pots for the commercial culture and sale of nasturtium

Recently biodegradable plant pots have been popularised by professionals and amateurs alike due to the growing trend of sustainability and environmental awareness. The effect of transplanting on the root systems of annual plants has been greatly studied. Many have found that the stress of transplanting could delay plant development by as much as 21% as the fibrous roots; essential to water uptake can easily get damaged or broken off. 

To generate energy roots use sugars that have been produced by the photosynthetic apparatus in the process of cellular respiration, requiring the presence of 02 and the expulsion of C02. As plastic containers do not allow the exchange of these gases it further contributes to the stress of transplanting. 

To test the viability of these peat pots this study compared the performance of Tropaeolum majus yield when it was grown for three months with and without these peat pots. It was found that when T. majus was cultivated in peat pots there was a 0.47% difference in plant height, 0.23% difference in leaf span and a 3.85% difference in dry weight; resulting in no significant differences. However, when comparing the root density differential from weeks 1 and 4, the control decreased by 2.32%. When weeks 1 and 4 were compared within the trial there was a 12.02% increase in root density; resulting in a significant increase in root density.

Influence of plant nutrition on the polysaccharides secreted by Arabidopsis and wheat roots

Roots secrete a mixture of polysaccharides in the form of mucilage which possibly initiates fungi symbiosis during macronutrient deficiencies. Key research has been undertaken to determine the composition of mucilage. However, this research occurred 30 years ago. More recent investigations have been undertaken but none have utilised antibodies to directly target each epitope of these polysaccharides. This study has utilised a battery of antibodies in ELISAs, EDCs and RE prints to directly detect polysaccharide alterations in Arabidopsis thaliana and Triticum aestivum in N, K and P deficient media. 

This study uncovered that LM14, LM19, LM21 and LM25 were the major epitopes of Arabidopsis and Triticum root mucilage indicating the presence of AGP, pectin, mannan and xyloglucan. The LM25 signal detected, increased or remained constant in both species when subjected to macronutrient deficiencies, particularly in –N and -P. Other epitopes declined or remained in a similar concentration. The rapid increase in LM25 signal was also present in the RE prints which revealed higher concentrations throughout Arabidopsis roots. LM25 is widely known to be concentrated towards the root caps. 

By excluding N, K and P this led to LM25 being evenly detected throughout the roots. The RE prints also uncovered that LM19’s signal rapidly diffused out of the roots without P but increased in concentration within the roots without K. LM25’s signal was heightened within the nutrient deficiencies, becoming more neutral in Triticum and more acidic in Arabidopsis, alluding to mucilage’s role in modifying the surrounding media’s pH and charge state.

Analysis of polysaccharides secreted by Arabidopsis and wheat roots

Plant roots are dynamic organs, which exchange molecules to and from the soil. Roots secrete a mixture of low molecular weight substances such as amino acids, and sugars, and high molecular weight substances including proteins, and polysaccharides, known as root exudate. A subset of these polysaccharides secreted, forms a gelatinous layer surrounding roots, known as root mucilage. 

To determine polysaccharides present within mucilage, polysaccharides had to be hydrolysed into their monosaccharides for linkage analysis. This investigation used monoclonal antibodies (MAbs) to directly detect the secreted polysaccharides. These MAbs were able to determine that arabinogalactan proteins (AGPs), homogalacturonan, heteromannan and xyloglucan were the major polysaccharides secreted by Arabidopsis thaliana and Triticum aestivum roots. When A. thaliana secreted polysaccharides were probed, pectin and xyloglucan were detected matching its cell wall polysaccharide profile. Xylans were only detected within T. aestivum, matching its cell wall profile. 

There was an abundance of xyloglucan secreted from T. aestivum. This was surprising as T. aestivum cell walls contain low amounts of xyloglucan. Using nitrocelulose sheets, secreted polysaccharides were differentially secreted along the roots of A. thaliana. AGPs were visible at the lateral roots, while homogalacturonan was visibly punctate. Xyloglucan was detected along the roots, suggesting that root hairs secreted xyloglucan. Possible interactions between AGPs, extensin, and xyloglucan were identified within T. aestivum and A. thaliana secreted polysaccharides, which have not previously been demonstrated. 

Neutral xyloglucan, acidic xyloglucan and pectic-xyloglucan were detected from A. thaliana and T. aestivum. These forms of xyloglucan occur separately in cell walls; however, they have not been shown to occur together or within secreted polysaccharides.

Analysis of polysaccharides released by plant roots

Plant roots have a dynamic relationship with the surrounding soil, which forms a vital interface for the terrestrial biosphere. Without a strong interface with soil, plants could not extract the necessary resources needed for growth. As a part of a multifaceted strategy, plant roots release a variety of high and low molecular weight compounds into the soil. This exudate is believed to increase water and nutrient uptake, form the first barrier of defence, and aid in the symbiosis with fungi and bacteria. 

This investigation reports on the identity and biochemistry of the polysaccharides released from the roots of several crops and one basal land plant, and explores their possible functions. Crops were grown hydroponically in order to isolate the polysaccharides released by their roots. After growth, the hydroponic media were screened with a library of monoclonal antibodies (MAb). The MAbs revealed the presence of arabinogalactan-protein (AGP), extensin, xylan and xyloglucan. 

Signatures of these polysaccharides were also determined by monosaccharide linkage analysis. By using anion-exchange Epitope Detection Chromatography, polysaccharides released into the hydroponic medium of the crops were separated for further immunochemical analysis. This analysis demonstrated that the polysaccharides released by wheat were part of a multi-polysaccharide complex, Root Exudate Complex 1 (REC1). A similar polysaccharide complex, formed of AGP-xyloglucan (REC2) was also found to be released by liverworts, which were not previously known to secrete polysaccharides. 

Novel soil analytics were developed in this study to decipher the effects of polysaccharides released by roots on soil aggregate status. Tamarind seed xyloglucan, xylan from birchwood, and isolated REC1 from wheat were each demonstrated to increase the abundance of soil aggregates, with REC1 shown to be most effective. This increase in the abundance aggregates may help plants to bioengineer the rhizosphere resulting in increased uptake of resources required for growth.