During 1993–94, in an area with a subtropical climate, 1500 m elevation, and 300 mm of precipitation, an experiment with `Golden Delicious' apples/MM.111 under irrigation was conducted with 11 treatments with three replications in a completely randomized complete-block design: T1, manual defoliation (27 Sept.); T2, 1% CuSO4 (15 Oct.); T3, 2% CuSO4 + Promesol (acido 2,3,4 trihydroxipentanodioico) (22 Oct.); T4, 1% CuSO4 + 0.1% Atlox; T5, 1% CuSO4 + 0.2% Atlox; T6, 1% CuSO4 + 0.1% Frigate; T7, 1% CuSO4 + 2% urea; T8, 2% sulfur; T9, 500 ppm tiadizuron + 1% carboxil; T4–T9, defoliation 12 Nov.; T10, control (natural defoliation on 3 Dec.); T11, 2% ZnSO4 + 0.07 carboxil (8 Nov.). All treatments received Atlox surfactant at 0.1%, except T4 and T5. On 11 Mar. 1994, trees received an application of 0.5% Dormex + 4% dormant oil. The percentage of terminal budbreak on 1-year-old wood was superior for T6, T9, and T11 compared with the control (11.7% budbreak on 2-year-old wood) for all treatments (except T1 and T3); all the treatments were superior to the control (47% budbreak), especially T2 (72.6%) and T9 (70.0%). The percentage of fruit set was similar in all treatments with the control (15.0%), except in T2 and T3, which set 7% more fruit.
Aroldo Rumayor Flores and Andres Martinez C.
C. Chervin, J. Raynal, N. André, A. Bonneau, and P. Westercamp
The effects of ethanol vapors, controlled atmosphere (CA) storage, and a combination of both on superficial scald development on `Granny Smith' apples (Malus ×domestica Borkh.) are reported. The major result was that ethanol vapors, applied in cold storage, prevented scald development over a week at 20 °C in apples that had been CA-stored for 4 months, then left for 1 month in cold air storage. Interrupting CA storage aimed to reproduce industry practices when fruit in part of storage rooms has to be sold and the remaining fruit is held in air for later sale. The estimated cost and further development of this method are discussed.
J.M. Vogel, A. Rafalski, W. Powell, M. Morgante, C. Andre, M. Hanafey, and S.V. Tingey
André Snyder, Matthew J. Morra, Jodi Johnson-Maynard, and Donald C. Thill
Brassicaceae seed meals (BSMs) average 6% nitrogen (N) by weight and contain glucosinolates (GLSs) that produce biologically active compounds. A two-season field study was initiated to determine how Brassica juncea L., Brassica napus L., and Sinapis alba L. seed meals, each with different glucosinolate profiles, alter carrot (Daucus carota L. subsp. sativus) growth, microbial biomass N (MBN), and soil N mineralization. BSM applications of 1 and 2 t·ha−1 36 days before planting did not influence carrot emergence, whereas carrot emergence decreased up to 40% in S. alba treatments seeded 15 days after BSM application. Crop quality was unaffected by BSM treatments and total fresh market yields were equal to or higher than the unamended controls in both years. At 4 and 8 days after seed meal application, MBN in the high-GLS B. juncea and S. alba treatments was 48% to 67% lower than in the low-GLS B. napus treatment. Seasonal apparent net N mineralized expressed as a percentage of the total N applied in the seed meals was unaffected by glucosinolate concentration and ranged from 30% to 81% across both years. BSMs can be used to increase soil inorganic N and carrot yields, but crop phytotoxicity is possible depending on the meal and its respective glucosinolate content. GLS degradation products inhibit microbial N uptake in the short term, but longer-term N availability is not compromised.
Serge Yelle, Richard C. Beeson Jr., Marc J. Trudel, and André Gosselin
Lycopersicon esculentum Mill. cv. Vedettos and Lycopersicon chmielewskii Rick, LA 1028, were exposed to two CO2 concentrations (330 or 900 μmol·m-3) for 10 weeks. The elevated CO2 concentration increased the relative growth rate (RGR) of L. esculentum and L. chmielewskii by 18% and 30%, respectively, after 2 weeks of treatment. This increase was not maintained as the plant matured. Net assimilation rate (NAR) and specific leaf weight (SLW) were always higher in C02-enriched plants, suggesting that assimilates were preferentially accumulated in the leaves as reserves rather than contributing to leaf expansion. Carbon dioxide enrichment increased early and total yields of L. esculentum by 80% and 22%, respectively. Carbon exchange rates (CER) increased during the first few weeks, but thereafter decreased as tomato plants acclimated to high atmospheric CO2. The relatively constant concentration of internal C0 with time suggests that reduced stomatal conductance under high CO2 does not explain lower photosynthetic rates of tomato plants grown under high atmospheric CO2 concentrations. Leaves 5 and 9 responded equally to high CO2 enrichment throughout plant growth. Consequently, acclimation of CO2-enriched plants was not entirely due to the age of the tissue. After 10 weeks of treatment, leaf 5, which had been exposed to high CO2 for only 10 days, showed the greatest acclimation of the experiment. We conclude that the duration of exposure of the whole plant to elevated CO2 concentration, rather than the age of the tissue, governs the acclimation to high CO2 concentrations.