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.
Sequential Planting for Single-Harvest Vegetables
ABSTRACT At Lane, Oklahoma, bell pepper (Capsicum annuum var. annuum L., cv. ‘Pip’) was followed in sequence with cucumber (Cucumis sativus L., cv. ‘Calypso’), or processing tomato (Lycopersicon esculentum L., cv. ‘Early Pear’), or bunch onion (Allium cepa [L.] Cepa group, cv. ‘Crystal Wax White’). Each crop was harvested once. Each sequence was begun monthly from mid-April to mid-July in each of two years, and with three fertilizer rates (recommended rate [1-fold], and 1.5- and 2-fold the recommended rate). For the earliest planting in both years, the time to first frost was long enough for a third crop. The fourth planting failed in both years. Tomato yields were below normal. The bell pepper and cucumber sequence had the highest yields for the first two planting dates. Increasing fertilizer rate reduced bell pepper yield, but had little effect on yield of crops planted in sequence with bell pepper. Further research is needed to determine how sequencing other crops will affect yield.
Germination ecology of Central Asian Stipa spp: differences among species, seed provenances, and the importance of field studies
Stipa-species are wide-spread in Central Asia, but sexual reproduction in the dry steppes is rare. To facilitate conservation and restoration of these important rangelands, we studied germination characteristics of three common Mongolian Stipa-species under field- and lab conditions. Seeds of Stipa krylovii, Stipa gobica and Stipa glareosa were sown at the study site in Southern Mongolia over two consecutive years during which period tests were carried out to ascertain whether competition or herbivory are the main constraints of seedling establishment. In addition, we tested germination and seed viability in the laboratory under two different temperature regimes (20/10°C and 8/4°C), as well as the effect of cold-stratification. The lab experiments also included S. krylovii seeds originating from three climatically different provenances. None of the three Stipa-species seedlings emerged during the first 2 years of the field study. However, after an unusually intense rain event in the third year, 3% of S. krylovii, 0.6% of S. glareosa and 0.1% of S. gobica seeds germinated in the study plots. The factors ‘sowing-year’ and ‘vegetation’ significantly affected seedling emergence, whereas grazing had no effect at all. Under laboratory conditions a high percentage of viable seeds of S. gobica and S. glareosa germinated at both incubation temperatures, and cold-stratification had no effect on germination or viability. Germination of S. krylovii seeds required warmer temperatures and cold-stratification had a positive effect. Such evidence for dormancy was more pronounced in seeds from the moister, northern provenances. Germination of Stipa-species in the field is rare and only possible under exceptionally moist conditions. Conservation should thus concentrate on steppe conservation rather than on restoration. Where artificial reseeding is necessary, differences among species and also among different seed provenances should be taken into account.