Phosphorous Nutrient Deficiency of Sunflowers, Helianthus Annuus

Phosphorous Nutrient Deficiency of Sunflowers, Helianthus annuus

Ngoc Chau Tran

Cal State Fullerton

Abstract: The objective of this experiment was to determine whether or not a complete nutrient solution would have increased stem width, height, and leaf length compared to 25% phosphorous. My hypothesis was that sunflowers with a complete solution of nutrients would have the same growth compared to sunflowers with 25% phosphorous deficiency. The experiment was conducted by setting up two groups of sunflower seeds, control and treatment. Each group contained five seeds. The nutrients were added when the seeds had germinated. The controls were treated with a complete nutrient solution, whereas the treatment was treated with 25% phosphorous deficiency. Both groups were watered regularly with the nutrient solutions until harvest time. The measurements of both groups were taken periodically. During harvest time, the healthiest plant in each pot was measured for stem width (mm), height (cm), and leaf length (mm). The results indicated that there was no significant change in the controls and treatments because the p-values of all three types of measurements were greater than 0.05. Therefore, the null hypothesis was accepted. Despite the insignificant results, observations and measurements of growth in both groups of sunflowers in terms of stem widths, lengths, and leaf lengths suggested that the presence or absence of phosphorous did influence the plant growths.

Introduction: The objective of this experiment was to determine the effects of nutrient deficiency in sunflower, H. annuus. My null hypothesis was that sunflower plants that were treated with a complete nutrient solution would be the same as plants that were 25% deficient in phosphorous. My alternate hypothesis was that sunflower plants with a complete nutrient treatment would have increased growth compared to plants with phosphorous deficiency with respect to stem height, width, and leaf length. Phosphorous is an essential nutrient for root formation, flowering, fruiting and ripening (Gayle et al. 2001). Ten elements that are required for normal growth in plants are carbon, hydrogen, oxygen, potassium, calcium, magnesium, nitrogen, phosphorus, sulfur, and iron. The absence of any one of these elements causes plants to display characteristic abnormalities of growth known as deficiency symptoms. Often such plants do not reproduce normally (Raven et al. 1999). One reason why phosphorous is essential in plants is because it is responsible for the general health and vigor of all plants. Some specific growth factors that have been associated with phosphorus are: stimulated root development, increased stalk and stem strength, improved flower formation and seed production, more uniform and earlier crop maturity, increased nitrogen N-fixing capacity of legumes, improvements in crop quality, and increased resistance to plant diseases (Webb 2002). One reason why sunflowers were chosen in the experiment was because sunflowers are easy to grow, the only single flower that grows as high as three meters at a rate of about 30 centimeters a week, and are really the most beautiful flowers in the world (Webb 2002). A study of nutrient deficiency was done by a group of two scientists to determine the effect on dwarf sunflowers.

Materials and Method: The sunflower deficiency experiments began on February 19, 2002 in the Cal State Fullerton green house and were harvested on May 3, 2002. Two groups of plants were made, the control and treatment. Each group contained five sunflower seeds. A complete nutrient solution of Ca(NO3)2, KNO3, KH2P04, MgSO4, Fe, and Micros was used in the control group to compare the differences with the treatment plants that were twenty-five percent phosphorus deficiency. Both groups were watered regularly (every 2 days) and the nutrient solutions were made four times throughout the experiment. The table below showed how the control and treatment solutions were done. The plants were checked periodically. Measurement of the longest leaf in (mm), stem in (mm), and height of each plant in (cm) were inserted into the Mann Whitney test to obtain the p-value of the nutrient deficiency experiment.

Table 1. Nutrient Experiment Deficiency of 25% phosphorous in Sunflower plants

Control Treatment of 25% phosphorous deficiency

Ca(NO3)2= KNO3=KH3PO4=MgSO4=Fe=Micros=Fill in half regular water in milk jar tank, and for every liter of water of the other half of the tank, five milliliter of each nutrient was added5 x 3.78 = 18.918.9 x 5 (number of nutrients) +18.9 = 113.4 Ðo complete nutrient solution Ca(NO3)2= KNO3=KH3PO4=MgSO4=Fe=Micros=P= 25%Fill in half regular water in milk jar tank, and for every liter of water of the other half of the tank, five milliliter of each nutrient was added excluding phosphorous.5 x 3.78 = 18.918.9 x 5= 94.9 + (5 x 3.78 x .25%) = 99.26

Results: As a result of the experiment, my null hypothesis accepted. Sunflower plants that were treated with a complete nutrient solution did not exhibit a significant increase in growth compared to the 25% phosphorous nutrient deficiency plants. The mean and variance in a complete solution for leaf lengths were 5.07 and 1.08 compared to 6.62 and 3.38 for the 25% phosphorous deficiency (Figure 2); mean and variance in a complete solution for stem widths were 0.35 and 0.01 compared to 0.33 and 0.01 for the 25% phosphorous deficiency (Figure 1); mean and variance in complete solution for stem heights were 7.80 and 0.27 compared to 12.9 and 0.24 for the 25% phosphorous deficiency (Figure 3). It was determined that there was not a significant change between a complete and 25% of phosphorus nutrient deficiency solution because the p-values for stem width, height, and leaf length were 0.44, 3.97, and 0.11 respectively, which were greater than 0.05.

Discussion: The results of the experiment showed that there was not a significant difference between the two groups of sunflower plants, a complete solution group (control) and, a 25% of phosphorous nutrient deficiency group (treatment), because the p-values of stem width, height, and leaf length were all greater than 0.05. In a complete solution, the stems were shorter and thinner compared to the treatment plants. Excess phosphorous may result in micronutrient deficiencies in iron and zinc (Webb 2002). One of the symptoms resulting from nutrient deficiency is chlorosis, which shows up first in young leaves, and is also reduced in size. Leaves are often closely spaced, forming a rosette and may be malformed (Gayle et al 2001). As such, chlorosis in iron deficient plants begins at the top of the plant and works its way down with leaves