This study was prompted by the huge feed grain deficits which increase annually in the Southeast. The need exists to find ways of increasing grain production efficiently. Cropping‐tillage systems designed to accomplish this were studied. Soybeans [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench.] were double cropped following wheat (Triticum aestivum L.) on a Blackbelt soil. No‐tillage and conventional tillage methods were compared for soybeans and grain sorghum; Conventional tillage was used for wheat. The 2‐year average yield of soybeans was 1,708 kg/ha (25.4 bu/acre) for no‐tillage and 2,250 kg/ha (33.4 acre) for conventional tillage. This difference was significant (P = .05) and was due mainly to lack of nutsedge (Cyperus sp.) control by herbicide alone in no‐tillage plots. In the third year when the crop was hand‐hoed, no yield differences occurred due to tillage methods. The 2‐year average yield of grain sorghum was 3,249 kg/ha (48.3 bu/acre) for no‐tillage and 3,868 kg/ha (57.5 bu/acre) for conventional tillage. When the crop was handhoed yield of grain sorghum was significantly higher for no‐tillage (5,072 vs 4.335 kg/ha). Wheat grown after soybeans yielded significantly (P = .05) more than wheat grown after grain sorghum. This difference was attributed primarily to the bneficial effect of residual N from the previous crop of soybeans. Based on current costs and prices, the soybean‐wheat double cropping system produced significantly higher net returns over specified production costs than the wheat. grain sorghum system.

Cleistogamous spikelets in sorghum [Sorghum bicolor (L.) Moench] form when the inner glume is rolled, clasping the internal flower structures and preventing normal opening of the glumes. Cleistogamy is controlled by two independently‐inherited genes. Indurate (hard) glume is dominant to papery glume. The rolled glume condition is dominant to unrolled. Indurate glume is epistatic to rolling, and only papery glumes can exhibit rolling. The F2 ratios from the cross (indurate glume × cleistagamous) show a good fit to a 12:3:1 ratio of induratercleistogamous (papery‐rolled): papery‐unrolled. This cleistogamy cannot be used to breed hybrids resistent to sorghum midge because one parent would be cleistogamous and prevent production of hybrid seed.

Syncytes occurred in a triploid and tetraploid progeny of an interspecific hybrid between Sorghum bicolor and S. halepense. That they originated by the fusion of two or more microsporocytes as a result of environmental conditions of high temperature and moisture stress is suggested. Meiosis was relatively regular in material collected from the same plants during favorable growing conditions. Coalescence of pollen mother‐cells varied from complete fusion into one polyploid cell to merely peripheral connection. Although meiosis was very irregular in these fusion bodies, sufficiently regular and functional fusion bodies, sufficiently regular and functional polyploid polyploid spores could be formed which may subsequently give rise to a polyploid series within a species.

Meiosis Of ‘Hodo’ sorgo was slightly more irregular than that reported for other varieties of Sorghum bicolor, notably by having a higher frequency of quadrivalent associations. Meiosis of the fertile interspecific S. bicolor × S. halepense hybrid was almost as regular as that of S. halepense, johnsongrass, and suggests close genomic relationship of the parental species. The 2n chromosome number was 20 for Hodo sorgo, 40 for johnsongrass, and 40 for the interspecific hybrid. The mean chromosome association was: Hodo sorgo, 8.2 II, and .91 IV; jonhsongrass, .19 I, 11.81 II, .09 III, 3.31 IV, .09 V, .28 VI, and .06 VIII; F1 hybrid, .04 I, 7.2 II, .17 III, 4.6 IV, .02 V, .7I VI, .02 VII, and .27 VIII. The frequent occurrence of quadrivalents in the hybrid suggests that part of the parental chromosomes are quite similar if not identical. Although the origin of octoploid (2n=40) johnsongrass is uncertain, experimental evidence substantiates the hypothesis that the species is an autopolyploid derived from S. bicolor.