Effects Of Combined Apllication Of Nitrogen, Phosphorus And Potassium On The Yield And Quality Of Marigold

The study was conducted to determine effects of nitrogen (N), phosphorus (P) and potassium (K) supply levels on growth, flower yields and xanthophylls content of marigold, using pots in the agroecology net-house of Gansu Agricultural University and field experiments in Gansu Farmland Reclamation Academy of Agricultural Science experiment station, respectively. There were 3 experiments consisting of 2 pots trials and 1 field experiment, one pot trial followed a completely random design with 3 N levels of 0(N0),100 mg N/kg soil(N1),150 mg N/kg soil(N2), respectively) combined with 3 K2O levels of 0(K0),75mg K2O /kg soil (K1),150 mg K2O /kg soil (K2), , another pot used N fertilizer sprayed on leaves with 4 concentration levels of 0.025%(N1),0.05%(N2),0.075%(N3),0.1%(N4). The field experiment followed regression optimized design adapting"3414"treatment model, combined with 4 N supply levels (at rate of 0 kg ha-2, 91.50 kg ha-2, 183.00 kg ha-2, 274.50 kg ha-2, denoting N0, N1, N2, and N3, respectively), 4 P2O5 supply levels (at rate of 0 kg ha-2, 69.00 kg ha-2, 138.00 kg ha-2, 207.00 kg ha-2, denoting P0, P1, P2, and P3, respectively) and 4 K2O supply rate of 0 kg ha-2, 37.50 kg ha-2, 75.00 kg ha-2, 112.50 kg ha-2, denoting K0, K1, K2, and K3, respectively). The results were showed below.1. N application combined with P and K had significant effect on growth of stem and leaf of marigold at all growth stages. N1K2 treatment had the highest plant height,number of leaves,leaf area and dry weight of leaves among treatments at jointing stage (2007-06-05) and budding stage (2007-07-05) in one pot trial, the morphological indexes of leaves and stem were increased significantly with N rates, N2K2 and N2K1 treatments had the highest morphological indexes. N fertilizer requirement of marigold was increased with growth periods, N1 and N2 were optimum options obtained the highest morphological index in early growth stage and medium - later growth stage, respectively.2. N application combined with K had significant effect on chlorophyll content of marigold at all growth stages in one pot trial. The equations between content of chlorophyll-a and chlorophyll-b and growth periods were parabola, increasing with growth stage extension in early, reaching the highest level at budding stage (2007-07-05) and the lowest level at senescence stage (2007-09-20).3. N application combined with K had significant effect on flower yields of marigold at all growth stages in one pot trial. It can be concluded K fertilizer addition advanced flowering process within N1 supply level, delayed flowering process within N0 and N2 supply level.N1K(2middle N and high K level)treatment had the highest number of flowers and dry weight of flower, while N2K2(high N and K level)treatment had the highest fresh weight of flower.4. N application combined with K had significant effect on growth and activity of root in one pot trial. Dry weight of root (DWR), root length (RL), root volume (RV), area of root total absorption (ARTA) ,area of root active absorption (ARAA) and root activity increased with N and K rates. The equations between DWR, RL, RV, ARTA, ARAA and root activity and growth periods are parabola, but the time when root indexes reach the highest differed among the treatments.5. The results of pot and field experiments are showed in following, the xanthophylls content of marigold reached the highest level at initial flowering stage.At the same time it decreased with growth periods.While too much nitrogen application(N3 : 274.50 kg ha-2) would have negative effect of fertilizer marigold on improving yield and quality. Xanthophylls content increased with K rates and P rates, leading K3 (112.50 kg ha-2) and P3(207.00 kg ha-2) treatments had the highest values.6. N application rate 183 kg ha-2 combined with P2O5 rate 138– 207 kg ha-2 and K2O rate 75 -112.5 kg ha-2 had highest flower yields in field experiment, foliar fertilization on concentration of 0.075 % was optimum option in pot trial. Base-fertilizers should be supplied in heavy amount, and topdressing fertilizers added according to crops requirements, the rule is that N fertilizer should be applied mainly before budding stage, while P fertilizer and K fertilizer emphasized during flowering stage. The results also suggested Budding stage and the period from 2nd flower harvest to 3rd flower harvest were optimum time for spraying fertilizer on leaves.