Crop yield response to water - Cra

Lead AuthorJordi Marsal(IRTA, Lleida, Spain)Sweet cherryIntroduction and BackgroundSweet cherry (Prunus avium L.), contribute modestly to the globaleconomy of deciduous fruit tree species. However cherry productioncan be crucial at local level in regions specialized for cherry growing,while for other areas it can become a good alternative whenever the marketfor the main fruit trees, such as apple, peach, and pears slows down. In 2009,there were 381 000 ha with an average world yield of 5.8 tonne/ha (FAO,2011). Figure 1 presents the production trends for the principal countries.Foliage development of cherries follows a pattern similar to that described inthe peach chapter. Cherry flowers develop in clusters from individual buds. Eachbud bears two-to-five flowers. These buds can be borne laterally in individualbuds or can be grouped in short spurs on two-year old twigs. Although cherryflowers are monopistil, in very hot summers many form two pistils that result indouble fruit. It has been argued that water stress could have a role in helpingthe formation of undesired double fruit, as it occurs in peaches, but there islittle evidence for this in sweet cherries (Beppu and Kataoka, 1999). In addition,air temperatures also affect fruit shape, becoming more irregular at high airtemperatures. Canopies can be cooled by using overhead sprinkler irrigation.The majority of commercial sweet cherry cultivars are self-sterile and thus theyrequire the use of pollinizers. Cherry trees are very vigorous and annual shootextension rates can surpass 1 m when they are young. Cherry trees have anupright growth habit and may need the use of adequate rootstocks to helpcontrolling vigour and induce early appearance of reproductive buds. Vigourcontrol is commonly managed with growth regulators.Stages of DevelopmentCherry flower buds, initiate just before the end of the shoot enlargementphase, and will continue to form and develop throughout postharvest (Flore,1994). Next spring cherry flowers will open before leaf appearance. Thereproductive growth can be divided into approximately three growth stages;similar to the case of early maturing peach fruit. Stage I comprises the firstmonth after full bloom and it is characterized by a rapid increase of fruitvolume which is mainly produced by cell division (Figure 2). The extent of theactivity in cell division will have a major contribution to fruit final size. StageII corresponds to the pit hardening phase and it can coincide with a slowingof the fruit growth rate (Figure 2). Finally, Stage III takes place around 20 days450crop yield response to water