Agriculture Reference
In-Depth Information
Some Agronomical Aspects and Cultural Practices
Genotypes and Cultivar Choice
Sources of genetic material have a great influence on yield and product quality
of protected crops. Different tolerances between hybrids and genotypes have been
documented for temperature (Ventura and Mendlinger 1999 ; Abdelmageed and
Gruda 2009 ), drought stress conditions, water shortage (Dumas et al. 2003 ; Niu
2008 ) and salt stress and fertilizer level (Wu et al. 2004 ; Wu and Kubota 2008b ;
Zushi and Matsuzoe 2011 ). In the future, plant breeding will form a strategy on its
own, adding to growth conditions improvement. Breeders can address improve-
ments of tolerance to diverse stress situations, as well as improvements in respect to
yield, earliness, and product quality. For example, Higashide and Heuvelink ( 2009 )
investigated yield improvement of tomatoes and found that an increase in yield over
the past 50 years in Dutch tomato production was caused by an increase in light
use efficiency of tested genotypes, resulting from a decrease in the light extinction
coefficient (a morphological change) and an increase in the leaf photosynthetic rate
(a physiological change).
Grafting
Although less frequent than the well-known fruit tree grafting, vegetable grafting is
getting more and more important. Interestingly, the early use of grafted vegetables
was associated with protected cultivation which involves successive cropping, and
is currently being globally practiced (Lee et al. 2010 ). The majority of grafted plants
belong to the Solanaceae and Cucurbitaceae families where the rootstocks of plant
genotypes have shown resistance to different soil-borne diseases. Since wild spe-
cies possess these properties, they are used as rootstock as well. By contrast, the
scions are usually used good productive and high qualitative genotypes. Although
first used to avoid serious problems caused by soil-borne diseases (Bletsos 2006 ;
Lee et al. 2010 ; Louws et al. 2010 ) this practice has been used to increase plant
vigor and yield (Lee et al. 2010 ; Gisbert et al. 2011 ), reduce stress situations caused
by adverse environmental conditions such as low soil temperature (Lee et al. 2010 ),
high salinity (Colla et al. 2010 ), high temperatures (Abdelmageed and Gruda 2009 ;
López-Marín et al. 2012 ), inadequate fertilization (Savvas et al. 2010 ) and water
stress and organic pollutant challenges (Schwarz et al. 2010 ). Recently, Flores et al.
( 2010 ) and Rouphael et al. ( 2010 ) also reported an influence of grafting on veg-
etables product quality. Despite these advantages, some disadvantages are noted
such as high costs of grafting seedling and sometimes low earlier yield. In order to
cut high costs, vigorous rootstocks are so far used in two and sometimes three-or-
four-stem-pruned-systems in tomato greenhouses. According to Lee et al. ( 2010 ),
research has been focused on developing efficient rootstocks and handy grafting
tools as well as grafting machines or robots to reduce the higher price of grafted
seedlings.
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