A multi-year orchard experiment was established to measure the performance of Rootpac®-R, Rootpac®-20, Rootpac®-40, and Rootpac®-70 rootstocks using ‘Redhaven’ peach (Prunus persica var. persica) as the scion, compared with the ‘Bailey’ peach seedling rootstock, the current industry standard. Tree survival after five years was 79% on Rootpac-40, whereas the remaining rootstocks showed no tree mortality. Tree vigour and canopy height and width were influenced by rootstock genotype beginning the year of planting in 2016. For the first five years of production, Rootpac-70 consistently produced the largest trees based on truck cross-sectional area (TCSA) and by year five, all rootstocks produced trees with similar TCSAs, except for Rootpac-70, which was 38% larger than Bailey. By year five, cumulative yields were greatest on Rootpac-70, which were 10% higher than Bailey; cumulative yields of Rootpac-R, Rootpac-20, and Rootpac-30 were 98%, 89%, and 84% that of Bailey, respectively. Cumulative yield efficiency was significantly influenced by rootstock although the magnitude of the differences was small and likely of insignificant commercial importance. Rootpac-40 consistently produced the largest fruit. These results are only reflective of the orchard establishment years and additional data are required before peach producers can make fully informed decisions concerning the rootstocks evaluated in this study for their orchard systems. However, at this juncture, all the Rootpac rootstocks evaluated in this study are likely to impart excessive vigour to be used in a higher density system and offer little advantage over Bailey.

Prohexadione-calcium (P-Ca) is widely used to reduce vegetative growth and labour costs associated with manual pruning. Orchard studies were conducted in 2012 and 2013 to determine the response of mature 'Empire'/M.26 apple trees to individual or combined applications of P-Ca, ethephon (ETH), trinexapac-ethyl (TE), and maleic hydrazide (MH). Sprays were repeated three times at approximately 2-wk intervals starting at petal fall. All compounds reduced extension shoot growth, ranging from 40%-73% in 2012 and 26%-57% in 2013, relative to untreated controls. The greatest reduction in growth was achieved with ETH in one year and P-Ca + ETH and MH in another. The tank-mixed combination of P-Ca + ETH improved vegetative control compared with each compound applied alone. MH caused foliar phytotoxicity and damage to the apical meristem, resulting in the stimulation of lateral shoot growth. Reduction in shoot growth from any of the plant bioregulators (PBR) did not reduce dormant pruning times in the spring following application. Total and marketable fruit yield was unaffected by the PBRs, although applications of MH resulted in a significantly higher number of fruit per tree and crop load but a lower mean fruit weight and percent marketable fruit.

Optimizing N fertilizer applications involves maximizing N use efficiency (NUE) while minimizing losses but depends on complex interactions of crop, soil, weather, and management practices. One approach may be to use controlled-release fertilizer that synchronizes N availability with plant demand. A field experiment at two Ontario locations from 2007 to 2009 compared split-applied ammonium nitrate (ANs) to preplant-applied poly-coated urea (PCU) and soluble N at a ratio of 75:25 at five N rates on late-season storage cabbage (Brassica oleracea L. var. capitata). Maximum yield and profit margins were obtained at an average of 286 and >300 kg N ha−1, but few differences among sources were observed. Compared with ANs, PCU did not affect plant N content, nor did PCU reduce soil nitrate or NUE, which indicates little differences in risk of environmental N losses between N sources. Dissolution from mesh bags indicated 5%–25% of various PCU formulations remained by harvest but 5%–10% remained by spring, which suggests conservation over the winter, a need to synchronize N release with crop uptake, and partially explains the lack of treatment differences. From agronomic, economic, and environmental perspectives, the tested PCU treatments for cabbage production in a humid, temperate climate were equivalent to the standard practice.

Increasing nutrient and water regulations have necessitated development of best management practices for application of nitrogen (N) and water. This study was conducted to determine if there was an optimal balance of N and water applied for late storage cabbage (Brassica oleracea L. var. capitata). Five rates of N and five irrigation rates arranged in a response surface design replicated three times were supplied to Huron cabbage grown on sandy loam soil to study the interaction of N and water applied. Plots were located at the University of Guelph, Simcoe Research Station, Ontario, Canada from 2003 to 2005. Total and marketable yields were maximized from a low of 278 kg ha-1 N in 2005 to above the highest rate tested (400 kg ha-1 N) in the other 2 yr. In 2005, there were 29 d above 30 °C and marketable yield was 49% lower than 2004, which had only 1 d above 30 °C. A target soil water value of 100% of field capacity was required to maximize yield in all 3 yr. More N is required as the water supply increases. The main influence of irrigation and N application was on head volume. Head density based on fresh weight was not influenced by irrigation or N application, but head density based on dry weight decreased with increased N application. Irrigation and N application should be managed concurrently to maximize yield and quality and N and irrigation efficiency for late storage cabbage. However, N and water will not prevent lost yield due to hot days, which suggests that late-cabbage yields are very sensitive to high air temperatures. Key words: Brassica oleracea var. capitata, cabbage, irrigation, fertigation, quality, nutrient management, air temperature

An understanding of plant nitrogen accumulation and soil nitrogen dynamics is needed to develop management practices that balance nitrogen requirements of vegetable crops with environmental protection. Field trials were conducted in 2001 and 2002 to determine the interaction of increasing rates of pre-plant nitrogen fertilizer with broccoli tissue nitrogen accumulation and soil nitrogen dynamics. Broccoli cultivars Decathlon and Captain were grown with seven rates of nitrogen (0, 50, 100, 150, 200, 300, 400 kg N ha-1) applied pre-plant as ammonium nitrate. Rate of nitrogen accumulation by the above-ground tissue biomass varied over time and among nitrogen treatments, ranging from 1 to 16 kg N ha-1 d-1. At harvest, tissue nitrogen was high, but nitrogen use efficiency was low when high rates of nitrogen were applied. Soil NO3--N content decreased from planting to harvest. At harvest, soil NO3--N increased with increasing rates of nitrogen, with the majority of NO3--N found in the top 0 to 30 cm of the soil. At 200 kg ha-1 applied nitrogen, plants recovered essentially all of the estimated available nitrogen and there appears to be little risk of nitrogen loss during the growing season. Approximately 130 kg N ha-1 was supplied by the soil during the cropping season. Soil and crop residues at harvest ranged from 96 to 330 kg N ha-1. This residual fertility poses a risk for nitrogen loss. Practical and cost-effective strategies are needed to manage residual nitrogen in the soil and crop residues to minimize loss and retain this nitrogen for subsequent crops. Key words: Brassica oleracea L. italica Plenck, nitrogen budget, nitrogen rates, nitrogen use efficiency, nutrient management

Nitrogen management is critical to the production of broccoli (Brassica oleracea L. italica Plenck). Field trials were conducted in 2001 and 2002 to determine the rate of pre-plant nitrogen required to optimize broccoli yield and quality. Seven rates of nitrogen (0, 50, 100, 150, 200, 300, 400 kg N ha-1) as ammonium nitrate were broadcast and incorporated before transplanting two broccoli cultivars, Captain and Decathlon. Maturity of the heads was delayed by 5 d at 0 kg N ha-1 compared with the other rates of applied N. Marketable yield was maximized at 243 to 272 kg N ha-1 for yield expressed in t ha-1 and 171 to 187 kg N ha-1 for yield expressed as cases ha-1. Averaged over cultivar and year the most economical rate of nitrogen (MERN) ranged from 298 to 309 kg ha-1, 50 kg higher than estimates for the maximum marketable yield derived from quadratic plateau models. The incidence of misshapen heads decreased and floret color improved as nitrogen rate increased, but hollow stem and head rot also increased with high rates of nitrogen. Floret NO3--N concentration increased and vitamin C concentration decreased at high nitrogen rates. Applying the rates of nitrogen required to maximize yield may have negative economic and environmental consequences. However, restricting nitrogen also jeopardizes both yield and quality. Hence, the optimum amount of pre-plant nitrogen to apply to broccoli that balances yield, quality, economics and environmental concerns remains a complex issue. Key words: Brassica oleracea L. italica Plenck, color, postharvest, nutrition, hollow stem, vitamin C

Chives, ( Allium schoenoprasum ) consumption and production are increasing in Ontario. Rust ( Puccinia allii F. Rudolphi) has been a problem with some chive cultivars for some growers, and in Ontario, basic information on production is nonexistent. The objectives were to identify cultivars with high yields, disease resistance and winter survivability. Plantings of six cultivars of chives were established in 2002 and 2003 in two contrasting environments, on organic (Kettleby) and mineral (Simcoe) soils; and one cultivar of garlic chives ( A. tuberosum ) at Kettleby. Leaves were harvested to a length of 30 cm, weighed and assessed for visible signs of rust. In Spring 2003, the number of dead plants was recorded to determine the overwinter survivability of each cultivar. Performance varied among cultivars and between locations. In Simcoe, Staro produced the highest yield in 2002 while generic (unnamed) chives produced the highest yield in the second year. In Kettleby, yield was similar among cultivars in 2002 but in 2003 generic chives produced the highest yield. Overwinter survival also varied between locations and second season yields were much higher in Kettleby. Less snow cover and subsequent winter injury is a possible explanation for the lower yields and poorer winter survival in Simcoe. No symptoms of rust were found in either location. Chives are a viable crop in Ontario, and appear to have different adaptability to regional soils and climates.

Sulphur may become deficient in intensive vegetable production systems that rely on chemical fertilizers. Yield of cole crops in response to sulphur fertilization has not been evaluated under Ontario conditions. Since calcium is linked to clubroot disease and tipburn, the sulphur fertilizer source is an important consideration. Rates of sulphur and calcium were compared for effects on yield using Novacal (a prilled calcium sulphate product), calcium nitrate and potassium sulphate for 3 yr for cabbage and 2 yr for broccoli on both sand and loam soils. There appeared to be no difference in yield from fertilizer source of sulphur or calcium. Applications of sulphur increased yield of Huron late storage cabbage averaged over years and soil with a mathematical maximum occurring at 55 kg S ha-1. Soil tests indicated levels of approximately 13–19 µg g-1 for sulphur prior to treatment. Yield of cabbage increased proportionately to calcium application averaged over 3 yr. No effect of treatment was observed on broccoli. Thus, soil levels of sulphur were probably limiting for late cabbage but not for broccoli. Sulphur shortage or deficiency appears to exist for late storage cabbage grown in Ontario. Lack of response of broccoli and no calibrated soil test for either element suggest that crops have to be evaluated individually under field conditions for sulphur fertilizer requirements. Key words: Cabbage, broccoli, calcium, sulphur, nutrition, yield

IN a previous letter we have proposed schemes for the disintegration of radioactive noble gases, formed by the bombardment of uranium with slow neutrons1. We repeated these experiments, passing the active gases over absorbent carbon instead of through water, which resulted in appreciably higher activities. We were able to confirm our earlier measurements and found 33 minutes as a more accurate value for the longer cæsium-period (instead of 30 minutes). It may be remarked that there is a satisfactory agreement between our results and those obtained by Hahn and Strassmann2.

IT has been shown by Hahn and Strassmann1 that uranium bombarded by slow neutrons forms a radioactive noble gas. We repeated their experiments, using the very strong neutron source of the Philips X-Ray Laboratory. About 500 cm.3 of a saturated solution of uranyl nitrate was irradiated. Air was bubbled through the liquid at a rate of 600 cm.3 per minute, then it passed through a tube filled with cotton-wool (length 15 cm.) and through a wash-bottle containing 40 cm.3 of water with a small amount of nitric acid and one drop of ammonia. After adding cæsium, rubidium, barium, strontium and lanthanum salts we obtained from the contents of this wash-bottle radioactive substances which could be precipitated together with cæsium, rubidium and barium.

The present investigation had its origin in an observation by one of us that in a vacuum tube containing sulphur vapour with an impurity of nitrogen, there appeared a previously unrecorded band spectrum which bore a striking resemblance to that of nitric oxide (NO). As only sulphur and nitrogen were known to be present, this similarity suggested that the new spectrum might be due to nitrogen sulphide (NS), since oxygen and sulphur have the same number of valence electrons. This supposition appears to be fully confirmed by the further experiments which have been made and by the vibrational analysis of the bands. The principal members of both sets of bands occur in the ultra-violet and nearly in the same region. It will be convenient first to give a brief account of the bands of nitric oxide. The Bands of Nitric Oxide . The principal bands of NO are well known from their occurrence in air vacuum tubes; they were long ago named the “Third Positive Bands of Nitrogen” by Deslandres, who, nevertheless, considered that the presence of both nitrogen and oxygen was necessary for their production. These bands were observed by Fowler and Strutt (now Lord Rayleigh) to appear in the spectrum of the nitrogen afterglow, and the opinion was expressed that nitrogen alone was capable of producing them. Subsequent work by Lewis and by Strutt,§ however, supported the view that the bands were produced only when both nitrogen and oxygen were present. During the present investigation, also, it has been found that the bands in question do not occur in vacuum tubes containing nitrogen when oxygen has been completely removed. These experimental results are in agreement with the conclusion derived from analyses of the band structure that the bands originate in the diatomic molecule NO.

Die vorliegende Arbeit enthält eine Untersuchung der verbotenen Hg-Linie 3680 63P2–73P2 im Magnetfeld. Die Theorie der durch elektrische Felder erzwungenen Dipolstrahlung ist daran experimentell bestätigt.

Zusammenfassung Fortsetzung der Analyse des Neonfunkenspektrums mit Hilfe der Zeemaneffekte. Das in einer früheren Arbeit mitgeteilte Niveauschema mit der Grenze3P ist durch einige Terme ergänzt. Die theoretisch möglichen Dublettermsysteme mit den Grenzen1D und1S des Ions sind gefunden worden. Die Tabelle von klassifizierten Ne II-Linien enthält 280 Linien. Dieg- Werte von 3s, 3p (3P,1D,1S) sind mitgeteilt und derg- Summensatz ist geprüft. Die Zeemaneffekte von 40 Linien sind mitgeteilt.

Die vorliegende Arbeit enthält eine eingehende Untersuchung der ersten2S-2D-Kombinationen von Na und K im Magnetfeld. Die Rubinowiczsche Theorie der Quadrupolstrahlung ist daran bestätigt. Der magnetische Umwandlungseffekt bei Quadrupollinien ist untersucht worden.

THE Zeeman effect is one of the most powerful methods of finding the causes of the occurrence of forbidden lines. The selection rules which govern it are quite different for ordinary lines, for quadripole lines, and for lines the appearance of which is due to external electric fields.

Die Zeemaneffekte von 90 Linien sind mitgeteilt worden. Mit Hilfe der Zeemaneffekte sind verschiedene neue Terme gefunden worden. Derg-Summensatz ist in einigen Fällen geprüft.

HOUSTON (Phys. Rev., 33, 297; 1929) has worked out an approximate quantum mechanical theory of the relation of the triplet interval ratio to the singlet-triplet interval for two electron configurations in which one of the electrons is in an s-state; he has also derived expressions for the g-values and for the intensities. Those formulæ show the variation with change of coupling.

Der Zeemaneffekt von 110 Ar II-Linien ist untersucht. Die von einem von uns (de Bruin) gegebene Analyse ist an dem Zeemaneffekt geprüft. Es folgt aus dem Zeemaneffekt, daß im Spektrum des ionisierten Argons normale und anomale Kopplungen auftreten; in den höheren Energieniveaus ist die Kopplung anomal. Für einige Termgruppen ist der „g-Summensatz“ geprüft.