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Abstract
The study was carried out during 2003 and 2004 seasons on a clay loamy soil at the Experimental Farm of Faculty of Agriculture, Moshtohor, Benha University, to study the responses of dragonhead plant to eight fertilization treatments. The seeds were planted on October 28th and on November 1st for 2003 and 2004 seasons, respectively and transplanted to the open field in December on rows at 60x40 cm distance.
Three sources of fertilizers were applied: 1) Mineral as ammonium nitrate (33.5% N); 2) Organic as compost (2.15% N); and 3) Biofertilizer to coat the seeds by a mixture of Azotobacter + Azospirillum + phosphate dissolver bacteria.
All treatment of biofertilizer contained unmeasured amounts of nitrogen. The soil received 150 kg calcium super phosphate + 50 kg potassium sulphate during its preparation. The suggested amount of nitrogen was added 15 and 45 days after transplanting as ammonium nitrate. The organic fertilizer was added after 15 days of transplanting.
Four kinds of data were recorded at six stages of the plant age: 1) plant growth; 2) oil production; 3) oil composition; and 4) nutritional status. The obtained results can be summarized as follows:
I. Plant growth
1) Plant length and number of branches per plant exhibited unclear and unstable responses.
2) The root weight per plant was not positively affected by any of the fertilization treatment.
3) The treatment of “¼ Min + ¼ Org + Bio” gave the highest weight of the aerial parts.
4) Average of the maximum growth rate occurred at 109 and 118 days after the transplanting for 2003 and 2004 seasons, respectively.
5) The “Bio” treatment tended to extent the growth season, while the “Org” one tended to shorten it.
6) The highest leaf production was observed on plants of “½ Min + Bio” treatment.
7) The highest flower production was obtained from “½ Min + ½ Org” treatment.
Volatile oil production
1) The percentage of volatile oil in leaves increased gradually as plant age progressed to reach its maximum value at 123 and 129 days after transplanting (at full bloom) for 2003 and 2004 seasons, respectively, then decreased at end of the season.
2) The maximum percentage of leaf oil was observed on “½ Min + ½ Org” treatment.
3) The highest yield of leaf volatile oil was obtained from the plants of “½ Min + ½ Org” treatment at the full bloom.
4) The highest percentage of flower oil was obtained at full bloom from “Org” treatment in 2003 season, while it was observed at full bloom from “½ Min + ½ Org” in 2004 season.
5) The highest oil yield of flowers was obtained from “½ Min + ½ Org” treatment after the full bloom and at the full bloom for 2003 and 2004 seasons, respectively.
6) The “½ Min + ½ Org” treatment gave the highest total yield (leaf + flower oil) at the full bloom.
1. Essential oil composition
i). General view
1. At full bloom, eight constituents were identified in the volatile oil by GLC investigation and amounted – in average, to 87.54 and 96.45% of the total oil constituents in leaf and flower essential oil, respectively.
2. Five constituents were considered as the majors (geraniol, neral, geranial, neryl acetate and geranyl acetate), which constituted 84.10 and 93.45% of the total oil of leaves and flowers, respectively.
3. Three constituents were considered as the minors (eucalyptol, linalool and nerol), which amounted to 3.44 and 3.00% of the total oil constituents of leaf and flower essential oil, respectively.
4. Citral (neral and geranial) was the main constituent and amounted to 34.93 and 37.96% in leaf and flower oil, respectively.
5. No qualitative difference was obtained between the essential oil of leaves and flowers.
6. There were some distinctive quantitative differences between the essential oil of leaves and flowers and could be summarized as follows:
a) Total relative amounts of the eight identified constituents were much higher in flowers oil than in the leaves one.,
b) The relative amount of citral was higher in flower oil.,
c) The relative amount of neryl acetate in leaf oil was more than twice as much in flower oil.
d) The flower oil was much less affected by the fertilization treatments than the leaf oil.
ii). Leaf oil
1. Total relative amount of the identified constituents in leaf oil reached to maximum values under the effect of “Min” treatment.
2. In general, formation of the minor constituents and the main constituents was favored by “Min” treatment.
3. Formation of citral (neral + geranial), which is responsible for the finest odor of the essential oil was favored by the “Bio” treatment.
). Flower oil
1. In general, constituents of the flower essential oil responded with less extent to the fertilization treatments. Only neral and linalool were obviously affected.
2. “Org”, “Bio” and “½ Min + Bio” treatments gave the highest values of neral in flower oil, whereas the “Bio” treatment gave the highest value of linalool.
i) NPK percentages
1. Average NPK percentage decreased in the leaves as the plant age developed to reach the minimum level at the full bloom, then rose again at end of the season.
2. There was an inverse relationship between the growth curves of the aerial parts or the leaf production and the NPK trends.
3. All the fertilization treatment increased the NPK percentages with nearly proportional to the amount of applied nitrogen either in the mineral and organic treatments (Con, and ½ Min + Bio, ½ Org + Bio and ¼ Min + ¼ Org + Bio).
4. The behavior of potassium either during the different stages of plant growth or at the end of season was different to the behavior of nitrogen and phosphorus.
ii) NPK uptake
1. All the fertilization treatments increased the NPK uptake in leaves with nearly proportion to the amount of applied nitrogen either in the mineral and organic treatments or in the bio-treatments
2. The highest NPK uptake was in “ ½ Min + Bio” treatment.
3. The highest oil yield was not proportional to the highest NPK uptake or percentage in leaves.