Cultivate differ inherently in their response towards drought. Only those adapted to arid and semiarid conditions become established into uniform and vigorous stands during germination under moisture stress and suboptimal temperature. Seed germination of four wheat cultivars, ‘Najah’ and ‘Mexi‐pak’ (Triticum aestivum L.), and ‘Hurani’ and ‘Jori’ (Triticum durum L.), were compared under suboptimal temperatures and various levels of simulated moisture stress. Components of water uptake, germination percentage, speed of germination, root growth, respiration rate, and germination recovery from stress were measured. The rate of water uptake decreased and the time required for germination increased when the seeds were incubated at 6 atm and higher. Seeds of the four cultivars germinated when their moisture content was approximately 50% on a fresh weight basis. Total germination was not affected by moisture stress levels up to 12 atm but was significantly reduced at 15 and 18 atm osmotic tensions. Rate of root growth, speed of germination, and respiration rates were inversely related to moisture stress. Low moisture stress (3 atm) did not inhibit root growth. Significant differences were found among cultivars in the parameters studied. Perforating the pericarps did not eliminate the differences in water uptake and respiration rates between cultivars. Prolonged exposure of ungerminated seed to high osmotic tensions at low temperatures showed high seed germination recovery. These data suggest that any of the germination criteria used can be effective in selecting droughtresistant cultivars.

Delayed leaf senescence has been found in a soybean population which maintains its chlorophyll and ribulosebisphosphate carboxylase activity in leaves and nitrogen fixation (acetylene reduction) activity in root nodules throughout seed maturation. Incorporation of delayed leaf senescence into an agronomically desirable genetic background may help to increase seed yield and symbiotic nitrogen fixation during seed development.

Irrigation applied once every 2 weeks, providing a seasonal total of 25.7 cm of water, produced the greatest seed yield, as well as an increase in the number of pods per raceme, number of seeds per pod, and 1,000‐seed weight. Plants irrigated at 3 or 4‐week intervals produced the highest number of hard seeds. The 50 ✕ 50 cm plant spacing produced well developed alfalfa plants which gave relatively high seed yields of 80 kg/dunum (1,000 m2) in 1966 and 65 kg/dunum in 1967. The variety ‘Hairy Peruvian’ produced more pods per raceme and more seeds per pod resulting in greater seed yield than that from the varieties ‘African’ and ‘Chilean.’ The Hairy Peruvian plants were the shortest of the three varieties grown.

Physiological responses to infection by strains of Rhizobium leguminosarum which differed in their capacity to reduce N2 were determined in 26-day-old pea plants (Pisum sadvum L. cv. Alaska) grown under uniform environmental conditions in the absence of combined N. The highest N2 reduction rates, calculated from H2 evolution and C2H2-dependent C2H4 production measurements, were approximately 6-fold greater than the lowest. Higher N2 fixation rates were associated with greater CO2 exchange rates (R2 = 0.92) and carboxylation efficiency (R2 = 0.99). Increases in the apparent relative efficiency of N2 fixation II-(H2 evolved in air/C2H2 reduced)l (acteroid efficiency) were associated with increases in whole-plant N2 fixation efficiency (N2/CO2 reduction ratio) (R2 = 0.95). Whole-plant dry weight and total N content were related by regression analysis (R2 = 0.98); both parameters were enhanced by increased N2 fixation in a manner analogous to previously reported increases caused by greater external applications of NH4'. These data reveal that photosynthetic parameters in genetically uniform host plants grown under identical environmental conditions are affected by N2 fixation characteristics of the rhizobial symbiont. The measured efficiencies of micro-and macrosymbiont are directly related under uniform environments.Dependence of N2 fixation on photosynthetic products is a concept supported by data of numerous investigations (3,4,6,10). It is axiomatic that the capacity of the photosynthetic apparatus to provide required photosynthate for all plant functions including N2 fixation is controlled to a large extent by the availability of reduced N. Previous work has shown that photosynthesis in 26-day-old Alaska peas (Pisum sativum L.) is strongly influenced by availability of reduced nitrogen, whether it is supplied exogenously or by the Rhizobium symbiosis (2). The present study was begun to determine whether photosynthesis in a genetically uniform host legume grown under controlled conditions could be altered by providing Rhizobium strains which differed in their capacity to reduce N2. photosynthesis, N2 fixation; and N content measurements were made as described previously (2), with the following exceptions. All plants were grown in the absence of combined N, and treatments consisted of eight single plant replications inoculated with Rhizobium leguminosarum strains TA 101 (obtained originally from J. J. Child, N.R.C. Saskatoon, Sask.), 175G 10, 128C53, 92A2, or 92FI (obtained originally from J. C. Burton, The Nitragin Co., Milwaukee). Nitrogen content, N2 fixation, RE3 (9), CER, CE, and C2H2 reduction data were evaluated by Duncan's multiple range test (5) to determine if significant differences existed in plants inoculated with different strains. The relationships of N2 fixation to CER, N2 fixation to CE, N2 fixation to N content, N content to dry weight, and RE to N2/CO2 fLxation ratio were evaluated by linear and nonlinear regression analyses. Data points were fitted with curves corresponding to the func...

of mineral nutrition on cooking quality of lentils. Can. J. plant sci. 5g: 165-168. A pot experiment was conducted on lentils to study the influence of major and trace elements on the-cooking quality of a hard cooliing lentil. cooking