, although closely related botanically, differ substantially in their ecologic requirements and yield performances ( Aliotta et al., 2004 ; Rosati et al., 2005 ). Unlike A. officinalis , the wild A. acutifolius is evergreen and prostrate, requiring
and/or amendments is essential for a proper nutrient supply and maximum yields. Chemical fertilizers often have low use efficiency, meaning that only a portion of the applied nutrients is taken up by plants ( Adesemoye et al., 2009 ). Estimates of
The U.S. State Dept. annually publishes estimates of narcotic drug crop production worldwide. The areas under cultivation are well known but yields per unit land area are not. Determining opium gum yield from illicitly grown poppy Papaver somniferum L. is difficult and dangerous. Removing plants from the field and harvesting gum in a safe place would allow us to measure gum yield from one short field visit. To interpret these results in terms of total gum yield from the field, one must know how the measured gum is affected by gum collecting method, capsule age, and phenotype. Opium poppy seeds from three phenotypes (purple, white, and red-white flowers) were grown in a greenhouse and plants were either cut at the soil level or left intact for opium gum harvest at 7, 12, and 22 days after flowering (DAF). Capsule firmness was measured to estimate gum yield and capsule age, and the relationship between total gum yield and yield from the first lancing was examined. The average gum yield (8.4 mg·g–1 dry weight capsule) for the purple-flowered phenotypes was 17% and 25% lower than for the white- and red/white-flowered phenotypes, respectively. Capsule firmness of the three phenotypes varied from ≈800 to 2300 N·m–1 as the capsule aged. Gum yield and capsule firmness increased with capsule age but the timing of those changes differed among phenotypes. No significant correlations were found between capsule firmness and gum yield or between capsule firmness and age. Therefore, capsule firmness cannot be used to predict gum yield or capsule age. Gum yield from the first lancing was linearly correlated with total gum yield (r2 = 0.82). Since this relationship changes with growing condition, it is insufficient to predict total gum yield. Gum yield from cut plants was significantly lower than from intact plants for all three phenotypes at 22 DAF and for white-flowered phenotypes at 12 DAF. No difference in gum yield was observed between cut and intact plants at 7 or 12 DAF for purple and red/white-flowered phenotypes. The relationship between gum yield from cut and intact plants was too variable to predict gum yield from intact plants by measuring gum yield from cut plants.
). Irrigation with BGW could cause salt stress, associated ion imbalances in crops, and decrease crop growth and yield ( Farooq et al., 2015 ; Munns and Tester, 2008 ). Reverse osmosis (RO) is a process that can desalinize BGW, consequently produces high
Pumpkins (Cucurbita pepo, C. moshata) were grown in northern Mississippi during 2000 and 2001 for the purpose of more narrowly defining plant population recommendations for commercial production in the humid southeastern United States. Four plant populations were examined for `Aspen': 908, 1361, 2045, and 3068 plants/acre (2244, 3363, 5053, and 7581 plants/ha, respectively) and for `Howden Biggie': 605, 908, 1361, and 2045 plants/acre (1495, 2244, 3363, 5053 plants/ha, respectively). Plant populations were adjusted by varying in-row spacing while holding between-row spacing constant at 8 ft (2.4 m). Plant population significantly affected yield of `Aspen' and `Howden Biggie'. Linear and quadratic terms were significant for `Aspen', with maximum yield (ton/acre and fruit/acre) for the quadratic relationship occurring at about 2045 plants/acre. In contrast, yield of `Howden Biggie' decreased significantly (ton/acre) and nonsignificantly (fruit/acre) in a linear relationship as plant population increased from 605 to 2045 plants/acre. Plant population significantly affected fruit weight and size. As plant population increased, weight and size decreased slightly but significantly in a linear relationship for `Aspen' (lb/fruit and inch3/fruit) and `Howden Biggie' (lb/fruit). The quadratic relationship for `Howden Biggie' (inch3/fruit) was significant and the minimum value occurred at about 1361 plants/acre. Plant population significantly affected pumpkin yield components associated with plant productivity. As plant population increased, number and weight of fruit per plant decreased sharply in a quadratic relationship for `Aspen' (lb/ plant and fruit/plant) and `Howden Biggie' (lb/plant). The linear relationship for `Howden Biggie' (fruit/ plant) also decreased significantly. At the highest plant populations for `Howden Biggie', 40% of the plants did not produce marketable pumpkins. In conclusion, recommendations of optimum plant populations for a semi-vining cultivar such as `Aspen' should be centered on about 2045 plants/acre. Published recommendations from Kentucky appear sound, advocating plant populations within the range of 1360 to 2720 plants/acre (3361 to 6721 plants/ha). For a vining cultivar such as `Howden Biggie', recommendations can be as low as 605 plants/acre. Published recommendations from Kentucky and Georgia, along with those published in the Vegetable Crop Guidelines for the Southeastern U.S., advocate plant populations for vining cultivars of approximately 725 to 1465 plants/acre (1790–3620 plants/ha). Our results with `Howden Biggie', a cultivar that produces larger pumpkins than most other vining cultivars grown for the wholesale market, indicate that producers of vining cultivars should use plant populations from the lowest values of these recommendations or use even lower values. Our results also indicate that growers can control size and weight of pumpkins by varying plant population, with increasing populations resulting in a slight decrease of size and weight.
their commercially desired height in Chile of ≈3.5 m. Trunk cross-sectional area was measured 20 cm above the grafting union. Tree volume was assessed during 2005–2006 (Year 4) based on spread and height from the lowest scaffold branch. Annual yields
application method of fertilization are fundamental to obtaining higher yields in blackberry ( Castaño et al., 2008 ). However, little research has been done on fertility and nutrient requirements for blackberry production in Brazil, and therefore remains a
Declines in cabbage (Brassica oleracea var. capitata) crop quality may result from delaying harvest to allow for greater total yield. An accurate, reliable, rapid and inexpensive method to estimate yield before harvest not requiring direct weight measurements would assist cabbage growers and handlers in harvest scheduling. Results from 3 years of study during which a tool to predict cabbage yield was developed and tested are reported here. The tool was developed using plots containing a total of 13 cabbage varieties (fresh market and processing types) planted in May to July 1999 and 2000 at the Ohio Agricultural Research and Development Center (OARDC) Vegetable Crops Research Branch in Fremont, Ohio. Exhaustive measurement of marketable yield and traits of hundreds of individual heads taken from these plots revealed simple mathematical relationships among head number, size, density, and yield. The tool was tested by comparing marketable yield predicted using a formula based on these head trait relationships to direct measures of crop yield in three different studies: 1) a factorial of nine varieties and 2 planting dates completed in Fremont in 1999, 2000, and 2001, 2) a survey of 12 commercial cabbage fields in northwestern Ohio encompassing six varieties and various planting dates and fertility regimens, in 2001, and 3) a factorial of 32 varieties and 2 planting dates (10 May, 20 June) completed in Fremont in 2001. The R2 for predicted and actual marketable yield in commercial fields and experimental plots ranged from 0.72 to 0.97. Of 510 individual estimatesof marketable yield, 48% were within 10% of actual yield values. The average quotient of predicted divided by actual marketable yield for 510 estimates made for commercial and experimental samples in 1999-2001 was 0.975. Results from this study were applied to the development of a table of potential use to crop managers in obtaining preharvest estimates of cabbage crop marketable yield. The table and its underlying assumptions are easily adjusted for local conditions.
physiological functions ( Nxawe et al., 2010 ) with undesired consequences on yield. The more this water-saving cultivation systems is being used (as happens in arid or semiarid regions such as the Mediterranean area where water, owing to its scarcity, costs
The effect of matric and osmotic seed priming on stand establishment and maturity of broccoli (Brassica oleracea L. var. italica) was investigated in three years at two locations in Virginia. Seeds (`Earlidawn') were primed at 1.1 MPa (68F for 7 days) either osmotically in polyethylene glycol (8000 molecular weight) or metrically in vermiculite (horticultural grade no. 2). In the frost year of the study, seeds were hand-seeded in August into crustprone soil with a mean temperature of 82F, and there were no differences in the percentage or mean time of seedling emergence between osmotic- and matric-primed seeds. Under cooler temperatures during the remaining two years of the study, priming increased the percent emergence and decreased the mean time of emergence by about 15 hours. Primed seeds did not increase yields or accelerate maturity in two out of three years. In the third year, the spread of seedling emergence times was less for primed seeds, which reduced plant-to-plant competition and hastened maturity. The primary benefit of primed broccoli seeds was faster emergence, which increased stands by reducing exposure to stresses that decrease emergence.