Because of the increased interest in the use of sorghum starch for industrial in Queensland, a survey of the starch content of grain sorghum grown in a number of Queensland districts was made. Forty-six samples, comprising 29 of Alpha, 12 of Texas 610, 3 of Brolga and 2 of Early Kalo, were analysed. At levels of about 8-10%, grain protein appears to be a fairly good index of starch content of sorghum grain grown in Queensland.

Wheat, oat, corn, and sorghum residues, collected at time of harvest for each crop, contained water-soluble materials that were toxic to growth of wheat seedlings. The order of increasing toxicity was wheat, oat, corn, and sorghum residues.'To evaluate the potential toxicity of a residue, the state of decomposition must be considered. Wheat and oat residues essentially contained no water-soluble toxic components after 8 weeks of exposure to field environmental conditions. Corn and sorghum residues had considerably more toxic materials at harvest and required about 22 to 28 weeks of decomposition before the water-soluble portion of the residues was relatively nontoxic. Tests of nine wheat varieties showed that the toxicity of wheat straw water extracts to germination and growth of wheat seedlings differed among varieties.

The spatial extent of the root systems of Xanthium Pennsylvanicum Wallr. (cocklebur), Tribulus terrestris L. (puncturevine), Kochia scoparia (L.) Schrad. (kochia), Digitarius sanquinalls (L.) Scop. (large crabgrass), Solanum rostratum Dunal. (buffalobur), Salsola kali L. var. tenuifolia Tauch (Russian thistle), Amaranthis retroflexus L. (redroot pigweed), and sorghum was determined at 10 weeks after transplanting and at maturity by digging and exposing the roots. The plants were grown without competition under favorable moisture conditions. At maturity, the root profile areas varied from 5.20 m² for pigweed to 17.93 m² for cocklebur. Plants within the extremes in increasing order of root profile area were sorghum, Russian thistle, buffalobur, crabgrass, kochia, and puncturevine.

Grain sorghum was planted to a uniform stand on Cecil sandy loam soil which had been fertilized with 408 kg/ha of a 4.0-5.3-10.0 (4-12-12) fertilizer. The plants were sidedressed with 56 kg/ha of nitrogen. Heads were harvested and threshed from 1-row plots 1.52 m long. Yields from these plots were combined in various combinations of rows and row lengths to determine the optimum plot size as measured by coefficients of variation. Data from this 3-year study involving different size and shape of plots for grain sorghum indicated that the optimum size plot consisted of 2 rows 4.56 m (15 ft) long.

Plant response to differences in water availability in the field was measured in grain sorghum during July in centra¹ Arizona. During two 24-hours periods, systematic measurements were made of meteorological factors, transpiration resistance, leaf thickness, leaf temperature, and evaporation, first in dry soil and then in wet soil, after irrigation. Limited soil water availability partially counteracted the normal, light-induced stomatal opening and led to increased daytime values of leaf diffusion resistance, decreased evapotranspiration, and leaf temperatures that exceeded air temperature, in contrast to plant reactions with water freely available. On the other hand, leaf thickness, as measured by a beta-ray gauge, decreased negligibly from the dawn reference value, even when the soil water content approached the 15-bar percentage. The absence of significant leaf response in this regard appears to be a failure of the beta-ray gauge technique to assess the water content of sorghum leaves.

Our purpose was to determine the effect of freezing temperatures on the viability of sorghum seed at different moisture levels and the damage to seed which may result from threshing. Viability of sorghum seed with a moisture content of less than 40% was not reduced when the seed was frozen for 12 hours at 1.7 or 0 C (29 or 32 F). The damage to seed with 35% moisture or higher increased with the duration of the freezing period when frozen at 3.3 C (26 F). The results from the two years indicate that the mid-twenties is a critical temperature for causing injury to seed with an excess of 20% moisture. Increased cylinder speeds of the thresher not only increased, the percentage of cracked seed, but also reduced the germinability of ‘sound’ seed and increased the percentage of abnormal seedlings. Injury also increased as the moisture content of the seed increased. Abnormal seedlings are probably due to injury to the radicle and plumule in the dormant embryo.

Dry weight and HCN concentration were determined in several parts of a sorghum-sudangrass hybrid. Leaf blade minus midrib was high in HCN at all growth stages but contributed decreasing amounts of total plant dry weight. Midrib, sheath, and stem portions decreased in HCN concentration with maturity. Decrease in HCN potential of the entire plant was due mostly to the proportional increase in weight of low-HCN-containing parts.

A positive regression between high yields and late maturity is demonstrated for grain sorghum. This regression should be considered when hybrid performance is tested. The use of this high yield-late maturity relationship should assist in the detection of the more productive hybrids at all levels of maturity.

Peliminary research indicates that forage sorghum hybrids and varieties differ in nitrogen and mineral contents. Contents of N, P, K, S, Ca, Zn, and Mn varied significantly among varieties. The varieties tested were below the postulated optimum beef cattle requirements for P, Ca, S, and Zn. Chelated minerals and sulfur added to the soil before planting did not affect the yield or mineral composition of the varieties tested.