USING SOME ISOLATES AND TRANSFORMANTS OF AZOTOBACTER TO REDUCE CHEMICAL NITROGEN FERTILIZER RATES IN GARLIC PRODUCTION

Document Type : Original Article

Authors

1 HortJ. Res. Institute., Giza

2 Dept. of Genetic; Fac. of Agrlc., Mlnla Univ

3 Hortlcultural Depart. (Vegetables), Fac. of Agrlc., Mlnia Univ., Minia, Egypt,

4 HortJ. Res. Institute., Giza,

Abstract

The present investigation was conducted at the laboratories of Genetics and
Horticulture departments. Fac. of Agric .• Minia University and farm of Mallawy
Horticulture Research Station. This study was carried out during the two successive
winter seasons of 200012001 and 200112002 to study the effect of application
dl1ferent genotypes of Azotobacter(Transformatlon procedure) and dl1ferent rates of
chemical N fertilizers in-gartic production (cv. Chinese). Wild type. four transtormants
of two Azotooocterspecies (two from each species) and three nitrogen rates i.e. 25%.
50% and 100% of the recommended dose (120 kg NlFed.) were used. The effects of
Azotobacter transformants and chemical nitrogen fertilizers and its interactions on
growth characters fresh and cured yield. yield components and nitrate and nitrite
content In cloves were studied.
The obtained results demonstrated that: (1)· DNA extract from two
Azotobacter species (A. vinelandii and A. chroococcum) grown under 200 mg/ml
chloramphenical was used to transform resistant to antibiotics isolates of the same
species sensitive to antibiotics. The highest frequency of transform ants (1 00X10~
was obtained when A. chroococcum was a donor and A. cnroococeum was a
recipient. Therefore, the highest frequencies were obtained from the intraspecific
transformation and the lowest frequencies 'oIIere obtained from the interspecific
transformation. (2)- Inoculation garlic plants cv "Chinese" with either transformants or .
wild type strain of Azotobacter improved most growth characters and yield addition to
reducing nitrate content in cloves. (3)- Fertilization with 60 and 120 kg. NlFed. gave
significantly higher values compared with 30 kg. NlFed. in respect of bulb weight and
clove weight. as well as total fresh and curd yields. (4)- The differences between 60
and 120 kg. NlFed. were insignifi~nt in most growth and yield measurements. (5)
The Azotobacter transformants differed significantly each from other in their effects
. on garlic growth and yields. The transformants (T3) and (T4) showed the highest
values in both seasons. (6) The nitrate contents in garlic cloves samples were
increased with increasing the applied N-chemical fertilizer' to the combined
biofertilizer treatment. An Increase (21.8%) In nitrate level was detected In garliC
samples produced from plants treated with chemical fertilizers compared with the
Azotobacter wild type treatment. Generally the plants fertilized with chemical fertilizer
contained highest value' of nitrate (217 mglkg) than those biofertilized with
Azotobacter.
In conclusion, inoculation garlic plants with Azotobacter bacteria
particularly transformants could be reduced using the chemical nitrogen
fertilizer by about 25% from the recommended dose to obtain the same
values of growth and yield. Moreover. nitrate content in cloves was reduced
after inoculation garlic plants with Azotobacter transformants.