With one exception, all nuts in the two tests were planted April 3, 1941. One of the two lots stored dry was soaked in water for five days, then planted April 7. Seedbeds were equipped with screen wire cloth at a depth of 10 inches.
~Results~: In both tests, fall nut planting resulted in the best germination. Germination was higher for nuts planted in the fall than for nuts stratified on the same day for spring planting, although the difference was significant only in the second test. Outdoor stratification produced the best results, followed in order by indoor stratification at 38-40° F and 45-50° F. None of the nuts stored dry germinated. Time of stratification proved to be important. Any delay after November 28 resulted in reduced and retarded germination and consequently smaller seedlings.
Depth of Planting and Seed Orientation
The effect of planting depth on germination and on seedling size was investigated by planting black walnuts one, two, three, and four inches deep. Other nuts were planted in three positions: (1) radicle end up, (2) on side, and (3) radicle end down.
~Results~: Germination was unaffected by any of these treatments. The emergence of the seedlings was retarded by deep planting and hence the final diameter of seedlings was smaller. There was little difference in seedlings from nuts planted one and two inches deep but they were noticeably larger than those planted 3 and 4 inches deep. Planting nuts with the radicle end down invariably produced seedlings with undesirable crooks in the root-stem region which made them unsuitable for grafting. Planting nuts radicle end up produced straighter seedlings than planting them on their side. The latter method was the most economical for nursery practice.
Seed Size
To study the effect of kernel size on size of seedling produced in the nursery, nuts from nine wild trees and Thomas nuts were planted. Kernel weights ranged from 1.21 to 5.61 grams; nut weight from 6.5 grams to 24.3 grams.
~Results~: With one exception where germination was poor, nuts with small kernels produced small seedlings and nuts with large kernels produced large seedlings. Under nursery conditions the need for uniformly large seedlings for budding and grafting is apparent. The results of this study indicated the desirability of using seed nuts with large kernels for production of understocks.
Seedbed and Budding Studies
Density of stand in seedbeds influences seedling size. As size of seedling is important in budding and grafting black walnut, information on the most desirable spacing in seedbeds was needed. In three seedbeds Thomas nuts were planted in three nut spacings: 4 x 4 inches, 5 x 5 inches, and 6 x 7 inches. In other plots nuts were planted 4 x 4 inches and after emergence the stand was thinned. All seedlings from the thinning test were set out in nursery rows the following spring and those large enough were budded in the summer.