Effect of Sequential Planting, Plant Replacement, and Planting Date on Marketable Yield of Bell Pepper, Capsicum annuum var. annuum L.
Earliest plantings of the bell pepper cv. Pip were on 16 May 1990 and 15 April 1991 at Lane, Okla. Additional plantings were at monthly intervals through July. Peppers were harvested weekly. Plants of the earliest plantings had marketable yields of approximately 21 Mg. ha-'. Marketable yields of later plantings were no higher than 8.6 Mg, ha-'. Combined marketable yields of sequential monthly lantings increased marketable yield to approximately 36 Mg.ha-(I a 1.7 fold increase over the earliest planting alone. W~th the earliest planting removed and peppers immediately replanted in June or July 1990 or May through July 1991, the marketable yield from subsequent plantings did not equal the marketable yield lost with the earliest planting maintained. Results showed sequential planting, with the earliest planting being no later than early May in the South Central United States, to be a viable method to increase marketable yield of bell pepper.
Influence of planting date and row covers on yields and crop values for bell peppers in Saskatchewan
In 1989 and 1990, bell peppers transplanted into the field in mid-May, late May or early June were grown with a black plastic soil mulch and no cover (NC) or under tunnels of perforated clear polyethylene (PT) or spunbonded polyester (ST). The ST treatment provided several degrees of frost protection, whereas the PT treatment appeared to increase the crop’s susceptibility to frost damage. Early planting had little effect on total fruit yields but did accelerate the harvest. In both years, the ST accelerated crop maturity and increased total fruit yields relative to the noncovered treatment. At times the PT improved crop development and increased fruit yields, but in many cases it reduced fruit yields relative to the noncovered treatment. By promoting early fruit set and development, early planting under the spunbonded row covers significantly enhanced the value of the crop, as early peppers command a premium price in Saskatchewan. Cumulative crop values for the PT treatments were generally similar to or p...
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.