Plant Growth And Development: Factors And Stages

Stages of Plant Growth and Development

In plant anatomy and physiology, plant growth and development is the process by which the plants develop new tissues and new structures from the meristems which are located at the tips of the plants’ organs or between the fully developed tissues of the plants. The growth process occurs throughout the whole life of the plants (Hunt, 2012). Plant growth and development involves various stages which the plant undergoes in its entire life. The main stages are:

Cellular differentiation, morphogenesis, and plant embryogenesis. This is the first stage in the life cycle of a plant. A plant begins to form after the fertilization of the egg cell and the sperm cell. After the process of fertilization, the division process starts which leads to the formation of the plant embryo through the process of embryogenesis. The process of embryogenesis leads to the formation of a complex cell which forms a root on one end while the other end forms the shoot. At the end of the embryogenesis process, the plant will have all the necessary parts which are needed for the life of the plant to start. Once the plant starts to shoot, it will develop the other organs (roots, stems, and leaves) through organogenesis process (Sanchez, Biancardi, and Goes, 2014, pp.458-466).

Morphological variation stage. This is the stage in the growth and development of the plants where different plants exhibit some natural variations in their forms and structures. The variations are openly witnessed on the leaves of the plants. The stems and the roots also undergo some variations, although in some plants it may be difficult to see the variations.

Leaf development stage. This is the stage where the plant starts massive development of leaves and branches. The plants develop leaves of different shapes and sizes depending on the type of the plant. The leaves are very important in plants as they are the major organs of photosynthesis (Dubey, Dwivedi, and Lahtinen, 2013, pp.134-142)

Flower development stage. In this stage, the plants develop the flowers used for the reproduction process. The flowers contain the male and the female reproductive organs of the plants, and therefore, help in the reproduction process. In some plants, the male and the female reproductive organs are found in the same flower while other plants have them separate in different plants (Takhtajan, 2009).

Fruits development stage. This is the stage where the plant produces some fruits and comes after the flowering stage. All the flowering plants produce fruits. However, it is important to note not all the plants produce some fruits as we have some non-flowering plants which produce spores or seeds instead of fruits (Pang, Luo, and Sun, 2012, pp.839-844). 

Having discussed the process of growth and development in plants, it is important to discuss some factors which affect the process of growth and development in plants. The major factors which affect the growth and the development of plants can be broadly classified into the genetic factors and the environmental factors.

The genetic factors are determined by the genes of different plants. The genes play an important role in the growth and development of the plants. The natural genes have been combined with some artificial genes improve the performance of some crops. The resulting hybrid crops have higher yields and have some improved traits as compared to the natural plants. Some of the desirable traits which can be observed in hybrid crops include good quality, higher resistance to different diseases, and great tolerance to dry conditions (Mallet, 2007, pp.279-283).

Factors Affecting Plant Growth and Development

The environmental factors also affect the growth and the development of plants in a great way. The environmental factors are the external conditions in the environment which affect the growth of plants. Some of the major environmental factors which affect the growth of plants include the temperature of the region, carbon (iv) oxide (CO₂) concentration, the moisture supply, the radiant energy, the soil structure, and aeration. The atmosphere composition, the biotic factors, the supply of the required nutrients from the soil, and existence or absence of some growth restricting substances also affect the growth of plants (Kramer and Kozlowski, 2012).

In this scientific report, we are going to discuss some factors which affect the growth rate of plants. We shall do a detailed analysis to examine how these factors affect the relative growth rate (RGR) of different plants. Relative growth rate is the rate of mass growth per unit mass which is already present. Relative growth rate is one of the major measures which are used to determine the growth potentials of different plants. The RGR is considered valid when the conditions of light, nutrients, and water are kept constants in all the plants under consideration (Rees, Osborne, and Turnbull, 2010). We shall use ten different native species, and each species will be represented by ten different seedlings. The results which we shall obtain will help us to come up with a comprehensive conclusion on some factors which affect the growth and development of plants and how they affect it. 

Objectives of the experiment

The major objectives of our experiment are to study some of the major factors which affect the growth and development of plants. The growth of the plants is competitive and is affected by various factors. In this research, we shall consider the species and the concentration of CO₂ as the major factors influencing the growth of the selected plants. These factors will be the major reasons behind the differences observed in the relative growth rates of the different plants under consideration.

The main objectives of our research are:

To investigate the relative importance of the differences among the species in physiology, tissue-traits, and biomass as the drivers of the relative growth rate.

To investigate whether the relative growth rate is affected by the concentration of CO₂. To be able to get a solution to this question, we shall expose the plants under consideration to different concentrations of CO₂ in greenhouses. The first set of plants will be grown in a greenhouse with an ambient CO₂ concentration of 400 ppm while the second set of plants will be grown in a greenhouse whose CO2 concentration has been elevated to 700 ppm.

To determine how these factors affect the relative growth rate, we shall use ten different species of plants. Each of the species will be represented by ten different seedlings as discussed above. Our relative growth rate experiment will be done under favorable conditions of non-limiting light, adequate water, and nutrients to ensure uniformity of the available conditions. The species of the plants to be used and their families are shown in the table below:

Methods and Materials

Table 1: A table showing the species and the families of the plants used in the experiment

S/N	Study species	Family
1	Alloxylon flammeum	Proteaceae
2	Angophora floribunda	Myrtaceae
3	Banksia aemula	Proteaceae
4	Corymbia maculate	Myrtaceae
5	Eucalyptus microcorys	Myrtaceae
6	Eucalyptus robusta	Myrtaceae
7	Lophostemon confertus	Myrtaceae
8	Melaleuca quinquenervia	Myrtaceae
9	Telopea speciosissima	Proteaceae
10	Tristaniopsis laurina	Myrtaceae

The seedling growth practical

Tube stocks of ten different native plant species were bought in early June.

Ten seedlings of each of the species were harvested to help in getting the initial data of the mass of the plants (the initial mass of the leaves, the stems, the roots, the total mass of the plants, and the total area of the leaves was taken into account)

The seedlings were then planted in large pots and were placed in greenhouses. Half of the seedlings were placed at ambient CO₂ concentration while the other half was placed at an elevated CO₂ concentration (400 vs. 700 ppm).

After 5 to 7 weeks, the photosynthetic rates of the plants was measured. The plants were also harvested to determine the new masses of the leaves, the stems, the roots, the total mass of the plants, and the total area of the leaves were measured. 

This section takes into account of all the results obtained in the experiment. In our case, the results of the experiment will be represented in table forms for easier analysis in the discussion section. We shall consider our results to be the data which was collected after the experiment. For a better understanding of this data, we shall first take the available data before the experiment is carried out. A comparison of the two types of data will help us to make the necessary observations and deductions from our experiment. We shall have various tables to represent the data before and at the end of the experiment. 

A summary of the data collected at the start of the experiment (15-June) is shown in the table below.

Table 2: A table showing the initial data of the plants collected at the start of the experiment on 15-June

S/N	Study species	Family	Leaf Mass(g)	Stem Mass(g)	Root Mass(g)	Total Plant Mass(g)	The total leaf area (cm2)
1	Alloxylon flammeum	Proteaceae	1.103	0.58	0.752	2.435	181.317
2	Angophora floribunda	Myrtaceae	0.589	0.295	0.45	1.334	106.788
3	Banksia aemula	Proteaceae	1.484	0.176	0.469	2.129	106.788
4	Corymbia maculata	Myrtaceae	0.358	0.139	0.179	0.675	47.009
5	Eucalyptus microcorys	Myrtaceae	0.56	0.338	0.471	1.369	75.48
6	Eucalyptus robusta	Myrtaceae	0.487	0.256	0.374	1.117	86.19
7	Lophostemon confertus	Myrtaceae	0.478	0.139	0.158	0.775	68.79
8	Melaleuca quinquenervia	Myrtaceae	1.271	0.774	1.267	3.312	120.1
9	Telopea speciosissima	Proteaceae	0.794	0.427	0.606	1.826	66.318
10	Tristaniopsis laurina	Myrtaceae	1.162	0.707	1.52	3.389	71.83

After recording the initial data at the start of the experiment, the plants were planted in different levels of CO₂ concentration. The levels of 400 ppm and 700 were used to help to show the effects of CO₂ concentration on the growth of plants. After 5 to 7 weeks, the plants were harvested, and the new masses of the leaves, the stems, the roots, the overall mass of the plant, and the total area of the leaves were recorded. The data recorded in the tables below was obtained.

Table 3: A table showing the new masses of the plants which were grown at a CO2 concentration of 400 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Stem Mass(g)	Root Mass(g)	Leaf Mass(g)	Total Plant Mass(g	The total leaf area (cm2)
1	Alloxylon flammeum	Proteaceae	11 Sep	88	1.878	1.912	6.322	10.112	808.304
2	Angophora floribunda	Myrtaceae	14 Sep	91	2.67	3.61	9.41	15.69	1037.748
3	Banksia aemula	Proteaceae	11 Sep	88	2.43	2.072	14.093	18.595	803.285
4	Corymbia maculate	Myrtaceae	14 Sep	91	5.497	5.767	24.482	35.746	1620.379
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	3.56	1.701	9.182	14.444	1198.551
6	Eucalyptus robusta	Myrtaceae	9 Sep	86	10.316	11.155	25.089	46.56	1881.375
7	Lophostemon confertus	Myrtaceae	14 Sep	91	7.647	6.444	24.521	38.613	2404.305
8	Melaleuca quinquenervia	Myrtaceae	6 Sep	83	9.923	11.476	22.636	44.035	1452.03
9	Telopea speciosissima	Proteaceae	11 Sep	88	1.9	2.4	8.203	12.503	554.205
10	Tristaniopsis laurina	Myrtaceae	14 Sep	91	2.204	2.708	9.776	14.688	653.203

Table 4: A table showing the new masses of the plants which were grown at a CO2 concentration of 700 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Stem Mass(g)	Root Mass(g)	Leaf Mass(g)	Total Plant Mass(g	The total leaf area (cm2
1	Alloxylon flammeum	Proteaceae	11 Sep	88	2.103	2.197	5.759	10.059	772.2
2	Angophora floribunda	Myrtaceae	14 Sep	91	3.566	4.421	13.623	21.61	1124.463
3	Banksia aemula	Proteaceae	11 Sep	88	1.778	1.995	12.464	16.237	617.965
4	Corymbia maculate	Myrtaceae	14 Sep	91	3.848	4.339	22.541	30.728	1246.906
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	2.442	1.075	6.332	9.848	714.015
6	Eucalyptus robusta	Myrtaceae	9 Sep	86	9.714	11.371	26.623	47.709	1758.23
7	Lophostemon confertus	Myrtaceae	14 Sep	91	5.196	5.987	18.33	29.512	1483.527
8	Melaleuca quinquenervia	Myrtaceae	6 Sep	83	13.011	11.06	24.329	48.4	1274.55
9	Telopea speciosissima	Proteaceae	11 Sep	88	1.559	2.619	7.444	11.622	373.274
10	Tristaniopsis laurina	Myrtaceae	14 Sep	91	2.226	3.531	10.159	15.916	588.632

 
After taking the data of the masses, we shall now take the data of the photosynthesis rate, the relative growth rate (RGR), and the net assimilation rate at the CO₂ concentration of 400 ppm and the concentration of 700 ppm to see how they relate.

Table 5: A table showing the photosynthesis rate, the relative growth rate (RGR), and the net assimilation rate at the CO₂ concentration of 400 ppm

Results

S/N	Study species	Family	Harvest date	Growth period (days)	Photosynthesis (?mol/m2/s)	Relative growth rate (g/g/d)	Net assimilation rate (g/cm2/d)
1	Alloxylon flammeum	Proteaceae	11 Sep	88	4.458	0.0162	0.00021
2	Angophora floribunda	Myrtaceae	14 Sep	91	4.184	0.0271	0.00040
3	Banksia aemula	Proteaceae	11 Sep	88	17.307	0.0246	0.00054
4	Corymbia maculata	Myrtaceae	14 Sep	91	3.216	0.0436	0.00087
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	6.642	0.0284	0.00039
6	Eucalyptus robusta	Myrtaceae	9 Sep	86	7.882	0.0434	0.00091
7	Lophostemon confertus	Myrtaceae	14 Sep	91	8.363	0.0430	0.00063
8	Melaleuca quinquenervia	Myrtaceae	6 Sep	83	7.463	0.0312	0.00092
9	Telopea speciosissima	Proteaceae	11 Sep	88	10.245	0.0219	0.00053
10	Tristaniopsis laurina	Myrtaceae	14 Sep	91	3.401	0.0161	0.00047

Table 6: A table showing the photosynthesis rate, the relative growth rate (RGR), and the net assimilation rate at the CO2 concentration of 700 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Photosynthesis (?mol/m2/s)	Relative growth rate (g/g/d)	Net assimilation rate (g/cm2/d)
1	Alloxylon flammeum	Proteaceae	11 Sep	88	7.97	0.0161	0.00021
2	Angophora floribunda	Myrtaceae	14 Sep	91	6.625	0.0306	0.00053
3	Banksia aemula	Proteaceae	11 Sep	88	22.319	0.0231	0.00055
4	Corymbia maculata	Myrtaceae	14 Sep	91	8.777	0.0420	0.00090
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	11.181	0.0238	0.00036
6	Eucalyptus robusta	Myrtaceae	9 Sep	86	15.169	0.0437	0.00098
7	Lophostemon confertus	Myrtaceae	14 Sep	91	10.553	0.0400	0.00069
8	Melaleuca quinquenervia	Myrtaceae	6 Sep	83	11.672	0.0323	0.00111
9	Telopea speciosissima	Proteaceae	11 Sep	88	14.212	0.0210	0.00063
10	Tristaniopsis laurina	Myrtaceae	14 Sep	91	6.74	0.0170	0.00056

From the results section, we can see how various factors affect the overall growth of the plant. In this section, we shall discuss how different concentrations of CO₂ affect the growth and development of plants. We shall consider the total masses of the plants, the photosynthesis rate, and the relative growth of different plants grown for about 5 to 7 weeks at CO₂ concentrations of 400 ppm and 700 ppm. We shall use five plants to make our analysis easier and have a clear visualization of the graphs to be used.

From the tables in the results section, we can see that the masses of the stems, the leaves, and the roots of most of the plants which were grown at a CO₂ concentration of 400 ppm were generally higher as compared to those grown at a concentration of 700 ppm. This means the overall plant masses of the plants which were grown at a CO₂ concentration of 400 ppm were higher than the overall masses of the plants which were grown at a concentration of 700 ppm.

We shall tabulate the data of five plants and represent the data in line graphs to have a clear visualization of the masses of the plants grown at the CO₂ concentrations of 400 ppm and 700 ppm.

Table 7: A table showing the masses and total leaf area at the start of the experiment

S/N	Study species	Family	Leaf Mass(g)	Stem Mass(g)	Root Mass(g)	Total Plant Mass(g)	The total leaf area (cm2)
1	Alloxylon flammeum	Proteaceae	1.103	0.58	0.752	2.435	181.317
3	Banksia aemula	Proteaceae	1.484	0.176	0.469	2.129	106.788
5	Eucalyptus microcorys	Myrtaceae	0.56	0.338	0.471	1.369	75.48
7	Lophostemon confertus	Myrtaceae	0.478	0.139	0.158	0.775	68.79
9	Telopea speciosissima	Proteaceae	0.794	0.427	0.606	1.826	66.318

Table 8: A table showing the masses and leaf area after 5 to 7 weeks of growth in a greenhouse with a CO2 concentration of 400 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Stem Mass(g)	Root Mass(g)	Leaf Mass(g)	Total Plant Mass(g	The total leaf area (cm2)
1	Alloxylon flammeum	Proteaceae	11 Sep	88	1.878	1.912	6.322	10.112	808.304
3	Banksia aemula	Proteaceae	11 Sep	88	2.43	2.072	14.093	18.595	803.285
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	3.56	1.701	9.182	14.444	1198.551
7	Lophostemon confertus	Myrtaceae	14 Sep	91	7.647	6.444	24.521	38.613	2404.305
9	Telopea speciosissima	Proteaceae	11 Sep	88	1.9	2.4	8.203	12.503	554.205

Table 9: A table showing the masses and leaves’ areas after 5 to 7 weeks of growth in a greenhouse with a CO2 concentration of 700 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Stem Mass(g)	Root Mass(g)	Leaf Mass(g)	Total Plant Mass(g	The total leaf area (cm2
1	Alloxylon flammeum	Proteaceae	11 Sep	88	2.103	2.197	5.759	10.059	772.2
3	Banksia aemula	Proteaceae	11 Sep	88	1.778	1.995	12.464	16.237	617.965
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	2.442	1.075	6.332	9.848	714.015
7	Lophostemon confertus	Myrtaceae	14 Sep	91	5.196	5.987	18.33	29.512	1483.527
9	Telopea speciosissima	Proteaceae	11 Sep	88	1.559	2.619	7.444	11.622	373.274

From the tables above, we can draw five line graphs to show the comparisons of the total masses of various plants which were grown at the CO₂ concentrations of 400 ppm and 700 ppm. The resulting line graphs will give a clear visual representation which will help us to make some useful deductions about the contributions of the concentration of CO₂ in the growth of plants (Jensen and Nielsen, 2007).

Figure 1: Line graphs showing the comparison of the total masses of various plants after growth in the CO2 concentration of 400 ppm and 700 ppm

 

From the line graphs, it is clear that the masses of the plants which were grown at a CO₂ concentration of 400 ppm were slightly higher than the masses of the plants which were grown at a CO₂ concentration of 700 ppm.

The total masses of the plants were minimum at the start of the experiment. When the plants were grown for 5 to 7 weeks in a CO2 concentration of 400 ppm, their total masses increased significantly. This increase in mass results from the increase in the number of leaves and roots and increase in the sizes of the leaves, roots, and the stem as the plant had undergone some growth and development process. The growth and development process is characterized by an increase in the number of roots and leaves and an increase in the sizes of the leaves, roots, stem, and the overall size of the plant (Abendroth, Lori, and Roger, 2011).

The masses of the plants obtained by growing the plants at a CO₂ concentration of 700 ppm were slightly lower as compared to the masses obtained after growing the plants at a CO₂ concentration of 400 ppm. It is expected that as the concentration of CO₂ increases from an ambient concentration of about 390 ppm, the rate of growth should increase exponentially with the increase in the concentration of CO₂ up to a CO₂ concentration of about 1000 ppm. However, we have some other factors which affect the growth of plants. Such factors include the presence of some growth restricting substances in the soil or the air and the differences in the species of the plants involved (Winner, Mooney, and Pell, 2012). These could be the major factors which resulted in lower masses of the plants after growing the plants at a CO₂ concentration of 700 ppm.

From the tables, it is also clear that the total areas of the leaves in the plants which were grown at a CO₂ concentration of 400 ppm are slightly higher than the areas of the plants which were grown at a CO₂ concentration of 700 ppm. This results from the fact that the growth which occurred in the plants which were grown at a CO2 concentration of 400 ppm was slightly more as compared to the growth which occurred in the plants which were grown at a CO2 concentration of 700 ppm.

A comparison of the photosynthesis rates of various plants after growing in CO₂ concentrations of 400 ppm and 700 ppm

From the available data, it is clear that the rate of photosynthesis in the plants which were grown at a CO₂ concentration of 700 ppm is higher than the photosynthesis rate of the plants which were grown at a CO₂ concentration of 400 ppm. The data of the photosynthesis rates of five plants at the CO₂ concentration of 400 ppm and 700 ppm is shown in the tables below:

Table 10: A table showing the photosynthesis rate, the relative growth rate (RGR), and the net assimilation rate of various plants at the CO2 concentration of 400 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Photosynthesis (?mol/m2/s)	Relative growth rate (g/g/d)	Net assimilation rate (g/cm2/d)
1	Alloxylon flammeum	Proteaceae	11 Sep	88	4.458	0.0162	0.00021
2	Angophora floribunda	Myrtaceae	14 Sep	91	4.184	0.0271	0.00040
3	Banksia aemula	Proteaceae	11 Sep	88	17.307	0.0246	0.00054
4	Corymbia maculata	Myrtaceae	14 Sep	91	3.216	0.0436	0.00087
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	6.642	0.0284	0.00039

Table 11: A table showing the photosynthesis rate, the relative growth rate (RGR), and the net assimilation rate of various plants at the CO2 concentration of 700 ppm

S/N	Study species	Family	Harvest date	Growth period (days)	Photosynthesis (?mol/m2/s)	Relative growth rate (g/g/d)	Net assimilation rate (g/cm2/d)
1	Alloxylon flammeum	Proteaceae	11 Sep	88	7.97	0.0161	0.00021
2	Angophora floribunda	Myrtaceae	14 Sep	91	6.625	0.0306	0.00053
3	Banksia aemula	Proteaceae	11 Sep	88	22.319	0.0231	0.00055
4	Corymbia maculata	Myrtaceae	14 Sep	91	8.777	0.0420	0.00090
5	Eucalyptus microcorys	Myrtaceae	6 Sep	83	11.181	0.0238	0.00036

From the tables above, we can draw line graphs showing the comparison of the photosynthesis rates of the plants at a CO₂ concentration of 400 ppm and 700 ppm. The line graphs will help us to get a clear comparison of the photosynthesis rates of the plants at the CO₂ concentration 400 ppm and 700 ppm.

Figure 2: Line graphs showing the comparison of the photosynthesis rates of various plants grown at CO2 concentrations of 400 ppm and 700 ppm

 

From the line graphs above, it is clear that the photosynthesis rates at a CO₂ concentration of 700 ppm are higher than the photosynthesis rates at a CO₂ concentration of 400 ppm. Photosynthesis is the biological process through which the plants manufacture energy (food) using sunlight. The major requirements for photosynthesis to take place are sunlight, water, chlorophyll and CO₂ (Govindjee, 2012). If all the other factors (sunlight, water, and chlorophyll) are held constant, the rate of photosynthesis will be directly proportional to the concentration of CO₂ (Souza et al., 2008, pp.1116-1127). Therefore, a higher concentration will result in a higher rate of photosynthesis as illustrated in this experiment where the rate of photosynthesis was higher at a CO₂ concentration of 700 ppm and lower at a CO₂ concentration of 400 ppm.

The relationship between the relative rate of photosynthesis and the concentration of CO₂ can be represented by the graph below:

Figure 3: A graph showing the relationship between relative rate of photosynthesis and concentration of CO2 in ppm

 

A comparison of the relative growth rates of various plants after growing in CO₂ concentrations of 400 ppm and 700 ppm

From the tables above, we can the relative growth rates of most of the plants grown at a CO2 concentration of 400 ppm were slightly higher as compared to the growth rates of the plants which were grown at a CO2 concentration of 700 ppm. This is clearly illustrated in the line graphs below:

Figure 4: Line graphs showing the comparison of the relative growth rates of various plants grown at CO2 concentrations of 400 ppm and 700 ppm

From the line graphs, we can see the relative growth rates of most plants are lower at a CO2 concentration of 700 as compared to the CO2 concentration of 400 ppm. The lower relative growth rates can be caused by the differences in the species used or some other growth restricting substances which could be available in the soil or the air (Winner, Mooney, and Pell, 2012).

Generally speaking, the growth process of plants is a very complicated process as it is affected by very many factors, some of which are genetic factors and others are environmental factors. Therefore, coming up with good curves to represent the growth process is usually a very hard task as you can’t accommodate all the factors which affect growth (Lindenmayer and Prusinkiewicz, 2012). However, after a series of research in this field, the scientists have come up with an exponential curve which represents the growth process. The scientists argue that the growth process is a very complicated process but can be represented with some exponential curves satisfactorily.

Just like the growth rate, the relative growth rate (RGR) is also exponential and can be represented using exponential curves (Beadle, 2014, pp.20-25). Given all the data, the exponential curves can be drawn using the following mathematical formula:

Where:  RGR is is the relative growth rate

ln is the natural logarithm

M0 is the initial mass of the plant

M1 is the final mass of the plant after growth

t1 is the starting time

t2 is the harvesting time

Figure 5: A figure showing typical RGR curves

 

The gradient of the exponential curves gives the value of the maximum relative growth rate (RGRmax).

The growth of plants is also affected by the differences in biomass allocation. As seen in the data in the excel files, the ratios of the root-mass ratio, the stem mass ratio, the leaf mass ratio, the specific leaf area, and the leaf area ratio are the major biomass allocations which affect the growth and the relative growth rates of plants. 

A summary of the discussion

From the discussion section, we can make the following summary:

The growth rate of plants can be measured by the increase in the masses or sizes of the leaves, stems, roots or increase in the overall masses of the plants.

The relative growth rate can also be used as a measure of growth in plants.

The growth rates of plants are affected by various factors. Among the major factors which affect the growth rates of plants as discussed above are:

The concentration levels of CO₂ in ppm.

The differences between the species of the plants.

The differences in physiology, for example, the photosynthetic rates of the plants.

Some growth-restricting factors which could be present in the soil or the air where the plants are growing.

The differences in the biomass allocation, for example, the ratios of the leaves to roots as elaborated further in the data in the excel files.

Conclusion

The growth and development process of plants is a very complex process as we have discussed above. We have very many factors which affect the growth and development of plants. Some of the major factors which affect the growth and development of plants which have been discussed above are CO₂ concentration, photosynthetic rates, species, biomass allocation, and growth restricting factors in the soil or the air. We have many other factors which affect the process of growth and results in the observable differences in the growth of various plants. The scientists have been carrying an extensive research in the field of plants to have an extensive knowledge on the growth of crops as this knowledge will help them to come up with the best species of crops which will be of great importance to the farmers.

CO2 concentration is one of the major factors which affect the growth of plants. Plants require elevated levels of CO2 concentration to boost the process of CO2. Therefore, people should adopt greenhouse farming to supply the plants with high levels of CO2 as this will help to improve the photosynthesis rates and the growth rates of the plants if all the other factors are kept constant. Improved photosynthesis and growth rates will yield into higher produce which will be beneficial to the people (Clarke, 2011).

References

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