Under normal field conditions, leaves of many typical sorghum [Sorghum bicolor (L.) Moench] lines such as BT×378, RT×7000, RT×2536, and SC 214(IS 1598C) senesce after grain maturity. In the field, several upper leaves of three partially converted lines [SC0056 (IS 12568), SC0599 (Rio), and SC0170 (IS12661)] from the sorghum conversion program remained green and apparently vigorous after grain maturity. This phenomenon of green leaf retention after the grain reached physiological maturity was termed “nonsenescence”. The purpose of this study was to compare standard (senescent) and nonsenescent lines to determine characteristics which describe differences between the two genotypes and to define desirable qualities of the nonsenescent lines. Senescent and nonsenescent lines were evaluated in the field for three growing seasons, 1974 to 1976, at College Station, Texas. The soil type was Ships clay (Udertic Haplustoll) intergrading toward a Norwood clay loam (Typic Udifluvent). Several plant characteristics (growth parameters, yield and yield components, basal tiller production, stem diameter, percent basal stem sugar concentration, and total leaf blade chlorophyll content) were measured to characterize genotypic differences. Experimental design was a randomized complete block with four replications. Growth data were recorded during the reproductive stage of development. The nonsenescent genotype required 2 days longer to reach 50% anthesis, averaged 3 to 4 cm shorter height, produced two to three more basal tillers per plant, had larger stem diameters, maintained higher basal stem sugar concentrations, and produced higher leaf blade chlorophyll contents than did the senescent genotype. Data involving leaves (green leaf number and weight, senesced leaf number and weight, leaf area index, leaf area duration, and leaf area ratio) favored the nonsenescent genotype. The grain‐leaf ratio of the senescent genotype exceeddthat of the nonsenescent genotype 30 days after anthesis because of a consistent reduction in leaf area due to senescence. Except for test weight (which was higher in the nonsenescent genotype), yield and yield components were generally inconsistent between genotypes. Parameters which could reasonably be measured in a breeding program to select for nonsenescent genotypes might include stem diameter and stem sugar concentration, tiller counts of a ratoon crop, and number of green leaves retained after grain maturity. Leaf area and chlorophyll measurements after the grain has reached physiological maturity might provide more conclusive Information on nonsenescence capability, but would probably not be feasible in a breeding program.

Weight per seed (SDWT) of maize (Zea mays L.) has been rcported to show no response when seed number was manually decreased. This field experiment was designed to test the generality of this lack of response across techniques of reducing seeds per ear and across genotypes. Bagging ears of a dent hybrid 2 to 4 d after silking reduced seed number by 15 to 45% and increased SDWT by 19 to 25%. The same treatment applied to a popcorn hybrid reducvd seed number by 12 to 36% with no significant increase in SDWC. Open pollinated varieties representing different seed sizes showed similar variability in SDWT response to reduced seed number. When SDWT of the dent hybrid and one of the varieties increased in response to reduced reed number, seed volume increased by a similar fraction. Removal of the apical half of the ear of the dent hybrid caused a different SDWT response than ear bagging. Such removal 5 to 15 d after silking decreased SDWT while removal 20 to 25 d after silking produced no significant change. Thus, it appeared that the response of SDWT to reduced seed number depended on genotype, how seed number was reduced, and when the reduction occurred. The reduction in SDWT due to early ear cutting was not due to a reduction in number of endosperm cells or volume of the developing seeds. The possibility of a physical restraint on SDWT by the developing pericarp of some cultivars was discussed.

Crop models for decision making should accurately simulate grain yields across a wide range of soils and climate regimes. This study was designed to evaluate two models' ability to simulate plot grain yields under diverse weather conditions and soils in Texas. The objective was to compare measured grain yields of maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] with grain yields simulated by the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model and to compare measured maize yields with grain yields simulated by a new version of the CERES‐Maize (Crop‐Environment Resource Synthesis) model. Using yield performance trials, both models were tested for their ability to simulate the mean yield for five years at each location and their ability to describe year‐to‐year variability in measured yields. Both models were tested at nine locations for maize and ALMANAC was tested at eight locations for sorghum. Model inputs included parameters for the soil type, planting dates, planting rates, and locally measured weather data. Mean simulated grain yield for each site was within 10% of the mean measured grain yield for all cases, except for CERES at Thrall, where mean simulated yield was 13% lower than mean measured yield. When the models did not account for a significant amount of the year‐to‐year variability in measured grain yield at a site, it was usually due to the narrow range of measured grain yields. The soils, weather, and crop parameter data sets developed here can be useful starting points for deriving data at similar sites, giving model users examples of realistic input data.

A simple and effective method to evaluate the ease of pericarp removal on lime (CaO)‐cooked corn (Zea mays L.) has been developed. Corn kernels placed in perforated nylon bags are lime‐cooked for 20 min at 98 to 100 °C and then stained in a solution containing methylene blue and eosine Y. We evaluated 11 corn hybrids grown at seven locations in 1989. The relative ease of pericarp removal was affected by hybrid and by growth environment, with hybrid differences being most important. The method requires a small sample, is rapid, and is ideally suited for ease of pericarp removal in screening large numbers of samples in breeding programs.

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