(parts per million) N, 50 p.p.m. P, and 



70 p.p.m. K was reached. Usim 



centr^al ,treatm#ifit, tfie|: concenp 



calcul§ted to be: 





f . K 



p.p.m. 



p.p.m 



8 



11 



25 



35 



50 



70 



75 



105 



92 



129 



this as -#16 

 itibns w^e 



average height of seedUngs 

 start of treatment, height 



f t I./ 



64 

 200 

 400 

 600 

 736 



The other elements were supplied in the 

 following concentrations: 



p.p.m. p.p.m. 



Calcium 120 Manganese 0.500 



Magnesium 48 Boron .500 



Sulfur 64 Copper .060 



Iron ' 3 Zinc .060 



Molybdenum .009 



A total of 15 treatments were tested, and 

 each treatment was replicated twice. 



The treatment solutions were not applied 

 until all seedlings had developed their first 

 true leaves. During this period, all pots 

 received periodic alternate applications of 

 de-ionized distilled water and of nutrient 

 solution. This solution (140 p.p.m. N, 100 

 p.p.m. P, and 175 p.p.m. K, and other ele- 

 ments as shown above) was appKed at one- 

 half strength. 



The growth period was 70 days, from the 

 time of the first application of the treatment 

 solutions to seedhng harvest. During this 

 period, the treatment solutions were added 

 twice weekly in 50 ml. amounts, alternating 

 with 50 ml. amounts of de-ionized distilled 

 water. 



The seedling response was measured in 

 terms of height growth and dry weight of 

 foliage. In addition, the amount of each 

 tested element in the foKage was determined. 

 Nitrogen determinations were made by the 

 semimicro-Kjeldahl method (6). Phosphorus 

 determinations were made colorimetrically, 

 using the vanadate-molybdate-yellow meth- 

 od (2). Potassium content was measured by 

 atomic absorption spectrophotometry (7). 

 Element content was expressed as a percent 

 of the dry weight of foliage. 



Height Growth 



if 



t^Bec&ise the 

 llarieilllat the 

 ^^owth^. was used to estimate the effect of 

 *^'treati™nt. On this basis, seedhngs in the 

 600-75-35 (N-P-K) treatment responded best 

 — their average height increased nearly 20 

 times to 339 mm. Seedhngs in the 400-50-129 

 treatment did nearly as well. The average 

 height of these seedhngs increased about 18 

 times to reach 200 mm. 



Ranking treatments in order of average 

 height increase shows that the differences be- 

 tween successive treatments were generally 

 small (table 1). 



Table 1 . — Average height at start of treatment, 

 at harvest, and height increase factor, by treatment 



N-P-K 



Average height 



Increase 



treatment 



Start 



Harvest 



factor 





mm. 



mm. 





600-75-35 



17 



339 



20 



400-50-129 



11 



200 



18 



400-50-11 



17 



234 



14 



400-8-70 



14 



176 



12 



400-50-70 



15 



185 



12 



200-75-105 



15 



177 



12 



600-75-105 



17 



190 



11 



200-25-35 



14 



155 



11 



736-50-70 



17 



188 



11 



600-25-35 



15 



151 



10 



400-92-70 



19 



174 



9 



200-75-35 



14 



126 



9 



600-25-105 



20 



178 



9 



200-25-105 



16 



132 



8 



64-50-70 



18 



115 



6 



Dry Weight of Foliage 



The average dry weight of foliage per seed- 

 hng varied by treatment, but no one level of 

 nutrient supply was best consistently. In gen- 

 eral, the treatments resulting in the greater 

 dry weights tended to have both nitrogen and 

 phosphorus in the middle range of concentra- 

 tions while the concentration of potassium 

 appeared to have little effect (fig. 1). In many 

 cases, the variation in average dry weight of 

 foliage per seedling was greater between reph- 



