PHYSIOLOGY AND MINERAL NUTRITION 99 



PHOTOSYNTHESIS. CARBOHYDRATE 

 AND NITROGEN METABOLISM 



It is assumed that photosynthesis and the carbohydrate and nitrogen 

 metabolism of the peanut are similar to that of other plants and a general 

 discussion of these topics may be omitted. However, it seems desirable to 

 mention the work of Moore (59) regarding the carbohydrate-nitrogen 

 balance in the metabolism of the peanut because of its possible importance 

 in relation to yields of field-grown plants. Moore produced plants with 

 various carbon/nitrogen ratios by altering the light and nitrogen supply. 

 High-nitrogen plants were succulent, dark blue-green in color, with 

 slender stems. High-carbohydrate plants were firm in texture, light in 

 color, with thick stems. Both types were weakly vegetative and non- 

 fruitful. Plants with a carbon/nitrogen ratio intermediate of the extremes 

 gave satisfactory yields. However, it was pointed out that the fruiting 

 tendency of the peanut was less sensitive to a change in the carbon/nitro- 

 gen ratio than that of the tomato plant. Results given in other papers 

 (10, 18, 37) suggest that the carbon/nitrogen ratio as affected by nu- 

 trient supply has considerable influence on flower and fruit production. It 

 is possible that many of the conflicting results in peanut experimenta- 

 tion would be explainable if such interrelations were better understood. 



GROWTH-PROMOTING SUBSTANCES 



Hormones or growth-promoting substances have not been used ex- 

 tensively on peanuts. Shibuya (73) reported that P-indole acetic acid in 

 lanolin, (proportion of 1 to 10), hastened germination when applied to 

 the scratched testa of seed of freshly harvested peanuts. He also reported 

 (75) that the number of flowers per plant was increased when sprouted 

 seed were soaked Yz and 2 hours, and unsprouted seed soaked 24 hours 

 in a water solution of 0.02 percent of that compound. A lanolin prepara- 

 tion of the hormone applied to sprouted seed hastened flowering and in- 

 creased the number of flowers. 



Naphthalene acetic acid and five commercial hormone preparations 

 were used with field-grown Spanish peanuts at the Alabama Station ( 1 ) . 

 The former and possibly one or two of the latter compounds slightly 

 increased nut production. However, there seemed to be little advantage in 

 their use and in some cases nodulation was depressed. Best results oc- 

 curred when the compounds were used in association with seed 

 inoculation. 



