Collins: Pueblo Indian Maize Breeding 



261 



varies in different varieties of maize. 

 As the mcsocotyl elongates, the coleop- 

 tyle with its firm, sharp point is pushed 

 upward through the soil. As soon as 

 the coleo])tyle emerges from the soil the 

 elongation of the mesocotyl eeases and 

 elongation of the internode bearing the 

 first true leaf begins, forcing open the 

 coleoptyle. 



If the seed is planted so deep that the 

 maximum elongation of the mesoeotyl 

 fails to bring the coleoptyle to the 

 surface the task of penetrating the soil 

 and reaching light devolves upon the 

 first true leaves. In comparison with 

 the sharp coleoptyle, these leaves are 

 but poorly adapted for forcing their 

 way through the soil, and if the tip of 

 the coleoptyle stops more than a few 

 centimeters below the surface these 

 leaves usually crumple and never reach 

 the light. 



In the varieties of maize commonly 

 grown the mesocotyl can seldom be 

 forced to a length greater than four 

 inches, while in the Hopi and Navajo 

 varieties this usually minute organ may 

 reach the relatively enormous length of 

 10 or even 12 inches, thus making it 

 possible for these Indians to plant their 

 maize deep in the ground where the soil 

 is moist and germination is assured. 



The mesocotyl is a beautifiil con- 

 trivance for removing the young seed- 

 ling from the seed and planting it at the 

 proper depth from the surface. The 

 true base of the plant is the base of the 

 coleoptyle, the point from which the 

 permanent roots arise. Since elongation 

 of the mesocotyl ceases when the tip 

 of the coleoptyle reaches the light, the 

 length of the coleoptyle determines the 

 depth at which the first permanent 

 roots develop. 



Figure 6 shows a seedling of Hopi 

 maize as it developed when planted 

 eight inches below the surface of the 

 ground. The first permanent roots can 

 be seen developing at the base of the 

 coleoptyle l}/2 inches above the seed. 



germination of NAVAJO MAIZE. 



In the fall of 1912, W. T. Swingle 

 and K. F. Kellerman of the Bureau of 

 Plant Industry visited the region about 

 Shiproek, N. M., in the Navajo reserva- 

 tion, and secured specimen ears of the 



maize grown by the Navajos. This col- 

 lection was kindly placed at the dis- 

 posal of the writer. Additional ' seed 

 was later secured through the courtesy 

 of Wm. T. Shelton, agent at Shiproek. 



It has been frequently stated that 

 the Navajos, like their neighbors the 

 Hopi and Zunis, plant maize at unusual 

 depths, 6, 12 and even 18 inches 

 having been reported. Since planting 

 at such depths was known to be im- 

 practicable with other varieties, an 

 experiment was planned to test the 

 ability of the Navajo maize in piercing 

 the soil. A box, 70 cm. by ZZ cm. and 

 34 cm. deep was sunk in the ground. A 

 quantity of sandy loam soil sufficient to 

 fill the box was slightly moistened and 

 carefully sifted. At one end the box 

 was filled to within one cm. of the top, 

 the soil sloping in a straight line to 

 within one cm. of the bottom at the 

 other end. 



Five seeds each of Navajo, Boone 

 County White, and Chinese maize were 

 placed in a row transverse to the 

 inclined surface of the soil, two cm. 

 from the top of the box. 



A similar row was planted at four cm. 

 from the top, and so on at the following 

 depths: 6, 8, 10, 12, 16, 20, 24, 28 and 

 32 cm. The box was then filled with 

 the soil and struck off level with the 

 top. The seeds germinated promptly, 

 and when the most advanced seedling 

 had reached a total height of about 60 

 cm. the plants which appeared above 

 the surface were dug up and the 

 mesocotyl and coleoptyle were measured 

 (see Fig. 7). 



Twelve cm. was the greatest 

 depth from which Chinese seedlings 

 appeared at the surface. Boone seed- 

 lings appeared from all depths up to 

 20 cm. while Navajo plants appeared 

 from all plantings to the very deepest, 

 32 cm. 



There were numerous instances where 

 the combined length of the mesocotyl 

 and coleoptyle was less than the depth 

 at which the seed was planted. This, of 

 course, means that the upper layers of 

 the soil were penetrated by the true 

 leaves. The maximum depth of soil 

 thus penetrated by the true leaves of the 

 plants of the Chinese variety was five 

 cm. One Boone plant forced its leaves 



