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Recent emphasis on energy problems has stimulated efforts to identify crops capable of producing high yields of biomass that can be converted into ethanol. The sorghum [ Sorghum bicolor (L.) Moench] crop includes cultivars and hybrids that vary widely in the relative amounts of grain and stalks produced, and also in the sugar content of the stalks. N39 × Wray, a relatively sweet hybrid with good grain potential, and Wray, a cultivar with sweet stalks, were compared for their grain and sugar yields, alcohol production potential, and other related characters. The hybrid produced heavier seeds, more seeds per head, and more heads per ha than the Wray. This resulted in a grain yield of 6630 kg/ha, about 3.4 times that of Wray. Wray produced about 10% more biomass with the stalk sugars accounting for about 80% of the total alcohol potential as compared to 45% for the hybrid. The total alcohol production potential (stalk plus grain) was 1.11 times as great for the hybrid as for Wray.

Most plant canopy and solar radiation studies have comprised theoretical considerations, assuming a randomly oriented leaf arrangement. Lacking are field measurements concerning culturally arranged plant canopies in relation to interception of solar radiation. The purpose of this study was to describe the light environment under field conditions below and within grain sorghum (Sorghum bicolor (L.) Moench) canopies. Visible radiation was measured in sorghum using sensors mounted on a traversing system and having about the same sensitivity to direction and spectrum as does a leaf. As much as 89% more light was transmitted to a sensor when it moved, between rows rather than across them. Therefore, measurement across rows is recommended. Light transmission profiles of sorghum canopies on clear and cloudy days were similar. Differences between transmission values over a diurnal period were less on cloudy than on clear days indicating more uniform light distribution. Visible radiation transmitted through sorghum canopies of .51-m rows as compared to sorghum canopies of .76- and 1.02-m rows or sorghum, canopies of .76-m rows as compared to sorghum canopies of 1.02-m rows was less. This would indicate more visible radiation would be available for photosynthesis with narrower row spacings. Extinction coefficients (K) for canopy layers were calculated and for each layer proceeding downward K decreased. Extinction coefficients of sorghum canopies of different row spacings decreased as row spacing increased. Differences between hourly values of K were less on the cloudy day than on the clear day. For all conditions minimum values of K occurred at solar noon. These results agree with theoretical data

Growth-promoting action of simazine and other s-triazine herbicides was detected by the use of sorghum (Sorghum bicolor [L]. Moench) callus tissue and the chlorophyll retention test. Soil application of simazine [2-chloro-4, 6-bis(ethylamino)-s-triazine] at sublethal levels nearly doubled the growth-promoting action of sorghum root exudates. Treated plants yielded up to 26% more total protein than untreated plants. This indicated that the level of callus growth-promoting action in the root exudate of the plant has a positive effect on its final total protein yield and confirms a positive effect of simazine on total protein content in certain instances. The results may provide a new understanding of the mode of action of s-triazines applied at sublethal levels in increasing protein content and certain enzymic activities of treated plants. It is speculated that the growth-promoting action of these herbicides is hormonal in nature and most likely kinetin-like.

A need to study the effect of a wide range of temperatures on early plant growth as well as seed germination of a wide range of sorghum [Sorghum bicolor (L.) Moench] germplasm led to the construction of a sand thermogradient sand table. The table was constructed so heat was transferred between water baths of two different temperatures. A continuous, linear thermogradient was established when the water baths were at 15 and 45 C. Other temperature differentials produced nearly linear gradients. Temperature deviation at any depth during the experiments never exceeded 1 C and usually was less. Germination and early growth of sorghum and corn (Zea mays L.) were measured to demonstrate the type of response curves that could be obtained with this apparatus. The table lends itself to many applications for physiological studies, including screening genetic material for temperature tolerance