An examination was made of the influence of atrazine, simazine, malathion and 2,4-D on total chlorophyll produc tion by Chlorella vulgaris, Ch/orococcum hypnosporum, Sfigeoc/onium fenl/e, Tribonema sp. , Val/cheria geminata and Oscil/aforia lulea.The herbicide 2,4-D in concentrations up to 100 mg/I did not alter chlorophyll production by the algae. Ch/O/·o coccum was not influenced by the pesticides . When added individually, atrazine, simazine and malathion inhibited chlorophyll production at a concentration of I mg/I or greater except for Sligeoc/onium, in which production was not influenced by I mg/I simazine . Results were variable when the pesticides were present individually at a con centration of I fig/I. The three pesticides stimulated chlorophyll production by Chlorella when present individually at 0· 1 and 0·5 fig/I. The same was true for simazine and malathion on Tr ibonema and Oscillaloria. A complete examination was not made for all the algae in these lower concentrations of pesticides. A significant interaction was present among atrazine, simazine and malathion. Combinations of two pesticides resulted in more inhibition, less inhibition or stimulation of chlorophyll production depending upon the con centrations used.Treatment of Va ucheria with 1 fig/I malathion caused a production of brown crystals inside the cytoplasm, a formation of a second cell wall inside the first and distortion of gametangia developing at the time of initial treatment.

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SUMMARYSeed germinability at high temperature (25 °C) was found to differ among golf course populations oiPoa annua L. located along a gradient of different intensities of turf irrigation and mowing practices. A seed germination index was calculated to express the effect of temperature on seed germination. The seed germination indices of the less managed populations from the golf roughs were uniformly low and less than 30 %, with a mean index of 5 %. Conversely, the germination indices of the golf green populations were high. Most seed families of the golf green populations had a germination index higher than 60%. A wide range of seed germination indices was found in seed families of the fairway populations, ranging from 10 to 90% with a mean index of 49%, and with a bimodal distribution. The results of this study indicate that rapid genetic differentiation in temperature-enforced seed dormancy among populations of Poa annua had taken place at the micro-ecological level.

The effect of tall fescue turf on growth, flowering, modulation, and nitrogen fixing potential of Lupinus albifrons Benth. was examined for greenhouse and field grown plants. No allelopathic effect was observed for lupine plants treated with tall fescue leachates. The nitrogen-fixing potential measured by nodule dry weight and acetylene reduction rates was not significantly affected by either tall fescue turf or low nitrogen fertilization. Both the greenhouse and field studies showed that the growth, sexual reproductive allocation, and number of inflorescences were significantly reduced when lupine plants were grown with tall fescue. The root length densities of tall fescue turf and lupine monoculture were measured. The tall fescue turf had 20 times higher root length density (20 cm cm-3 soil) than the lupine plants monoculture. This suggests that intense competition at the root zone may be a dominant factor which limits the growth of the lupine plants. The reproductive characters of the lupine plants was improved by phosphorus fertilization. Transplanting of older lupine plants into the turf substantially alleviated the tall fescue turf competitive effect.

The effect of tall fescue turf on growth, flowering, nodulation, and nitrogen fixing potential of Lupinus albifrons Benth. was examined for greenhouse and field grown plants. No allelopathic effect was observed for lupine plants treated with tall fescue leachates. The nitrogen-fixing potential measured by nodule dry weight and acetylene reduction rates was not significantly affected by tall fescue turf.Both the greenhouse and field studies showed that the growth, sexual reproductive allocation and number of inflorescences were significantly reduced when lupine plants were grown with tall fescue. The root-length densities of tall fescue turf and lupine monoculture were measured. The tall fescue turf had 3 20 times higher r0ot-length density (20 cm cm-soil) than the lupine plant monoculture. This suggests that intense competition at the root zone may be a dominant factor which limits the growth of the lupine plants.The flowering characters of the lupine plants were improved by phosphorus fertilization. Transplanting of older lupine plants into the turf substantially alleviated the tall fescue turf competitive effect.