Effects of wheat straw mulch on soil water and soil temperature in the 0- to 7.6-cm soil layer and their subsequent influence of plant development and grain yields of winter wheat (Triticum aestivum L., ‘Winalta’) were evaluated over a 3-year period. Mulch rates of 0, 1,680, and 3,360 kg/ha were applied randomly or in bands centered over or between wheat rows planted in 35-, 70-, and 90-cm row spacings. Band applications of straw were applied at the same rates per unit area as that covered by randomly applied straw but in band widths of 18, 35, and 45 cm for the respective row spacings. In a time sequence of correlations, number of tillers and number of adventitious roots were positively correlated with a moist soil-degree day index (P=.01) based on May soil water and soil temperature measurements, number of adventitious roots was positively correlated with number of heads/ha (P=.01), and number of heads/ha was positively correlated with grain yield (P=.01). Numbers of adventitious roots, tillers, and heads and final grain yields were dependent upon the soil water and soil temperature of the 0- to 7.6-cm soil layer during May. The intermediate straw mulch rate (1,680 kg/ha) applied randomly or in bands over the wheat row significantly increased the number of moist soil-degree days and grain yields in 2 of 3 years compared to bare fallow or the high straw mulch rate (3,360 kg/ha).

Photosynthesis (net CO₂ assimilation) was measured on two winter and one spring wheat cultivars (Triticum aestivum) at three stages of cold hardening. Photosynthesis during hardening was characterized by decreasing rates of CO₂ assimilation and reduced response to light and temperature changes. The winter wheats, ‘Vermillion’ and ‘Seneca,’ had higher rates of photosynthesis at all stages of hardening than did the spring wheat, ‘Justin.’ Vermillion, the most winter hardy cultivar, had significantly higher photosynthesis than Seneca when rates were averaged over all variables. Treatment of the plants with (2-chloroethyl) trimethylammonium chloride did not produce any significant changes in any of the photosynthetic parameters studied. No significant differences in specific rates of photophosphorylation or Hill reaction were noted among the cultivars, in contrast to the varietal differences found in whole plant CO₂ assimilation rates.

Intermountain drylands lose water from the root zone during the summer of fallow even though they receive a monthly average of 3.1 cm of precipitation. Soil water content in the 7.5- to 15-cm seed zone at the end of summer fallow was related to soil water content at the Lime tillage was initiated in the spring. Fall soil water content was not appreciably affected by variations in summer rainfall. Adequate soil water for winter wheat Triticum aestivum L. em Thell) emergence was best assured by initiating summer fallow tillage when the water content in the 7.5- to 15-cm layer was relatively high, rather than depending on summer rain to rewet this layer.

At the Kotkaniemi Experimental Farm at Vihti it has been possible to shorten and strengthen the straw of winter cereals, spring wheat, four- and six-row barley, and oats by using Chlormequat (CCC) which has resulted in a decrease in lodging. The greatest increase in the grain yield was achieved with spring wheat, the following in order were rye, barley, and winter wheat. The treatment did not wholly eliminate the lodging of rye but it did prevent the rye from lodging before blooming. Results achieved with treatment of winter wheat with Chlormequat varied each year. The straw of barley and oats was also distinctly shorter and in some cases even an increase in grain yield could be noticed. The later the spring treatment, the more the straws of cereals shortened. In practice, however, preference has to be given to the time point of weed control when attention is paid to increase in grain yield and to other viewpoints. In favourable growth conditions and under heavy fertilization, the increase in the grain yield caused by Chlormequat treatment is at its greatest. In unfavourable conditions the increases in grain yield are small and the grain yield may even decrease. | Klormekvatti-käsittelyllä (CCC) on Kotkaniemen koetilan olosuhteissa voitu lyhentää ja vahvistaa syysviljojen, kevätvehnän, monitahoisen ohran ja kauran kortta, mikä ilmenee lakoontumisen pienenemisenä. Pyrittäessä voimaperäisellä lannoituksella korkeaan satotasoon, on tällä seikalla huomattava käytännöllinen merkitys useimmilla tutkituista lajikkeista. Aineiston vähäisyyden takia ei päätelmiä voida tehdä Ruso-vehnän ja Pendek-kauran osalta. Suurimmat sadonlisäykset on saatu kevätvehnällä, sitten ovat olleet järjestyksessä ruis ja ohra syysvehnän jäädessä viimeiseksi. Syysviljoilla kevätkäsittely on ollut tehokkaampi kuin syyskäsittely. Kaikilla viljoilla on korsi lyhentynyt sitä enemmän, mitä myöhemmin keväällä käsittely on suoritettu. Ottaen huomioon sadonlisäykset ja muut käytännön näkökohdat, on etusijalle asetettava se ajankohta, jolloin rikkakasvien ruiskutukset suoritetaan. Yleisenä piirteenä on todettavissa, että klormekvatti-käsittely lisää satoa eniten silloin kun kasvuolosuhteet sallivat korkean satotason muodostumisen. Myös sadon laatu paranee tällöin sen ansiosta. Epäedullisissa kasvuoloissa sadonlisäykset jäävät vähäisemmiksi ja sadot saattavat jopa alentua. Tämän vuoksi lannoituksen voimaperäisyyden ja maan muun kunnon huomioonottaminen on tarpeellista klormekvattikäsittelyn yhteydessä mm. käyttömäärien kohdalla.

The effects of several sources of phosphorus on the emergence of winter wheat (Triticum aestivum L.) were compared when applied in a band with the seed under controlled temperature and moisture conditions. The detrimental effects of a given fertilizer treatment on emergence increased as temperature increased from 15 to 25C. Increasing soil moisture stress from 1 to 3 bars also reduced emergence. The harmful effects of increasing the temperature from 15 to 25C were greater than the harmful effects of increasing moisture tension from 1 to 3 bars. Emergence was reduced to a much greater extent on a sandy soil than on a medium textured soil for a given fertilizer treatment. The effects of temperature, moisture, and soil texture appeared to be cumulative. Ammonium polyphosphate, ordinary superphosphate, and concentrated superphosphate had approximately equal effects on emergence and were much less detrimental than monoammonium and diammonium phosphate which were about equal. Ammonium phosphate sulfate decreased emergence to a much greater extent than any other source. Banding of concentrated superphosphate with the seed reduced emergence as much as 40% in the field. This reduced emergence, however, had no effect on yield of grain.

Simazine [2-chloro-4,6-bis (ethylamino)-s-triazine] and terbacil [3-tert.butyl-5-chloro-6.methyluracil] were applied at subherbicidal rates as protein and growth regulatrs to wheat at two Michigan locations in 1968 and 1969 and at Ciudad Obregon, Mexico in 1969. Different N levels were used at all locations. Winter wheat from Michigan and spring wheat from Mexico were planted at two Michigan locations to determine the effect of herbicide and N treatments on the growth, yield, and protein content of the second generation. Neither supplemental N nor herbicides increased the yield and protein content in all experiments. Nitrogen increased both the yield and protein content in three out of the four tests. Subherbicidal applications increased the protein content in all tests and also the yield in two tests. Increases in seed protein due to both herbicide and N applications were reflected in higher yields the next generation in all three Michigan field experiments. Yield was directly correlated with seed protein content, but not with seed size. In one test in Mexico the effect of protein in the seed on the next generation was eliminated by 120 kg N/ha applied at time of planting.

In the tests on the Kotkaniemi Experimental Farm at Vihti in 1966—69 PCNB-treatments in most cases gave considerable increases in grain yields of rye and winter wheat. In addition to customary treatments, research has been carried out the possibility of reducing the loss of PCNB in rains in the autumn by using a fixing material. The results of the tests are negative, however. The spreading of 50 % PCNB-spray powder, containing ammonium sulphate as filling material, on the loose snow or the placement of PCNB with a fertilizer under the snow in early winter has in the preliminary tests given as good results as spreading before the fall of snow. The results indicate that the time of the PCNB-treatment may safely be postponed to a later date than is customary at present. | Tehdyissä kokeissa vuosina 1966—69 on Kotkaniemen koetilalla Vihdissä saatu PCNB-käsittelyllä useimmiten huomattavia sadonlisäyksiä rukiilla ja syysvehnällä. Alustavat kokeet osoittavat, että 50 %:sen PCNB-ruiskutejauheen, joka sisältää täyteaineena ammoniumsulfaattia, levitys alkutalven löyhälle lumelle tai sijoitus lumen läpi rivilannoituskoneella lannoitteeseen sekoitettuna maan pinnalle, antaa yhtä hyviä tuloksia kuin ennen lumen tuloa tapahtunut levityskin.