Some Aspects of Growth of Adansonia Digitata L.

The effects of three nitrate sources on the growth as well as the effects of water stress and the antitranspirant, Vapor Gard (VG), on trans-pirational water loss and on the growth of Adansonia digitata were investigated. All three sources of nitrate, potassium nitrate (KNO₃), ammonium nitrate (NH₄NO₃) and magnesium nitrate (Mg(NO₃)₂) significantly enhanced shoot heights with NH₄NO₃ giving the highest growth at an application rate of 175 kg ha⁻¹. Only KNO₃ significantly enhanced root growth when it was applied at 100, 125 or 150 kg ha⁻¹. The highest dry weight values for both below-and above-ground tissues were obtained with KNO, application at 200 kg ha⁻¹ followed by NH₄NO₂ at 125 kg ha⁻¹.

The oldest leaves of all plants subjected to water stress senesced and abscised while the remaining leaves showed acute symptoms of wilting and transpired lest towards the end of each stress cycle. In contrast, plants which were sprayed with VG before being water-stressed did not shed their leaves, showed only minor symptoms of wilting and transpired much less. However, untreated plants and plants which were sprayed with VG but which were well watered had higher fresh and dry weights than the former two treatments. The application of KNO₃ ar NH₄NO₃ as a nitrogen source in raising young plants of this species is recommended and the foliage treatments with VG during periods of water stress will prolong their survival in the field.