Effects of N、P、K Nutrient on Growth and Development of Helianthus Annuus and Flowering Regulation of Basical Research
|School||Nanjing Agricultural College|
|Course||Ornamental Plants and Horticulture|
|Keywords||Helianthus annuus N.p.K Vegetative growth Photosynthesis Flower Bud Blooming date regulation|
Ornamental sunflower (Helianthus annuus), originating in North America, an annual herb of Compositae, Because it’s type dances, lush foliage and large, colorful, flowers can serve as a potted plant, cut flowers, ground plant flowers and widely used. At present, the research of mineral nutrition on vegetative growth and regulation of ornamental sunflower has not been reported up to now. In this study. we use ’Fuyang’ as materials, discussed the effect of N,P,K nutrients to their growth and development. And through the development of Helianthus annuus bud differentiation process, master Helianthus annuus flower bud differentiation period, to using appropriate methods to control flowering purposes. The results are as follows:1. Mineral nutrition requirement of ornamental sunflower on growth and development were studied. The results showed that:sunflower seedling growth stage, nitrogen fertilizer had on the greatest impact plant height and stem diameter, and when it was 180mg/L had the largest plant height, maximum leaf area and maximum stem diameter, P and K had no significant effect. In the budding stage, Nitrogen had the significant effects on plant height, when N was 180mg/L, sunflower have a maximum height value, And fresh and dry weight and soluble sugar also have the greatest impact. K had the most effect on chlorophyll content and soluble protein. P effect on flowering reached a significant level and with 120mg/L enter the earliest flowering. Flowering period. N had a significant effect on plant height and chlorophyll content, and the nitrogen with 180mg/L has a maximum height value. P affected fresh and dry weight, soluble sugar, soluble protein most, to reach a significant level, and with 120mg/L has a maximum height, maximum leaf area values. K with 200mg/L had a maximum leaf area, maximum stem diameter, maximum height. Therefore, the experimental conditions for ornamental sunflower growth and development is N(180mg/L)、P(120mg/L)、K(200mg/L). 2. Nitrogen, phosphorus and potassium different levels on the effect of photosynthetic characteristics of Helianthus annus was analysised. The results showed that:under the condition of this experiment, N was the most important factor influencing on the photosynthetic ability of Helianthus annuus, including the net photosynthesis rate (Pn)、intercellular CO2 concentration (Ci)、transpiration rate (Tr) and stomatal limitation (Ls),was remarkably affected by N and treatment with 280 mg/L gave the best effects. K had remarkable effects on stomatal conductance (Gs) and the most significant effects shown when the K concentration reached 200 mg/L. Water use efficiency was also affected by K. But P effects on all character of photosynthetic parameters and water use efficiency was not significant. Therefore, N,P.K fertilizers can be reasonably effective in improving Helianthus annuus photosynthesis and photosynthetic rate.3. Using Helianthus annuus buds as materials, we took the observation on histological structure of different stages of flower bud differentiation process by paraffin sections and anatomical observations. The results showed that:under the condition of this experiment. 15 days after planting, Three pairs of true leaf buds begin to enjoy sunflower bud differentiation; 18 days after planting. That is,4 pairs of leaves to the faceplate when viewing the original body of sunflower bud differentiation; At 20 days after planting, the five pairs of true leaves into the floret differentiation stage of ornamental sunflower.4. Regulation of flowering time of Helianthus annuus with the treatment of shading and Gibberellin was conducted. The results showed that:the appropriate shading treatment could delay the blooming date of Helianthus annuus, to the best effect of shading 6h, respectively, under normal conditions compared with squaring period, flowering period was delayed 14d, 10d. shading treatment also had a certain influence on growth and development of Helianthus annuus, inhibit the growth of plant height, leaf number increased, stem diameter and flower stem diameter. Gibberellin spraying made the blooming date earlier, The concentration of 150mg/L spraying once a day had much better effect compared with the control, squaring period, flowering period was ahead of 11d,13d respectively. In addition, with the gibberellin treatment, plant height、leaf number were greater than control plants, stem diameter values、flower-bearing stem diameter values compared with control plants decreased.