Annona Species Monograph.pdf - Crops for the Future

Chapter 10. Agronomy
fertilization programme during the period before flowering and harvesting to
improve the fruit quality. Commercial liquid fertilizers can be applied 2-3
times a year (Torres and Sánchez, 1992; Pinto and Silva, 1997). Cherimoya
trees are sensitive to boron and zinc deficiencies, therefore, boron at 2.0 g/m 2
should be applied to the ground area below the canopy. Spraying of 0.1% of
zinc sulphate, applied at monthly intervals, will correct any zinc deficiency.
In addition, boron and calcium sprays during flowering and early fruit set
may be beneficial in reducing the incidence of internal fruit browning (Torres
and Sánchez, 1992; Undurraga et al., 1995; Hermoso and Farré, 1997;
Bonaventure, 1999).
Fertilization with easily leachable nutrients, such as N and K, should be split
into three or more applications during the year. Fertigation techniques
(application of fertilizers through the irrigation system) is the best
recommendation for this multiple application practice, providing a quicker
and more controlled response than soil surface application; this practice also
promotes a higher yield and fruit quality. However, there are no scientific
results published on this technical issue which can confirm the
recommendation for annonas.
Organic cultivation of annona trees is a recent practice with no conclusive
studies to identify scientifically acceptable recommendations for production.
However, an increasing number of growers are reducing the use of
agrotoxins and increasing the use of organic or biological products to
improve fruit quality for market. Today, the foliar application of
microorganism mixes (commercially named as EM-4 and EM-5), as well as a
bioactivators (commercially named Aminon-25), seem to enhance plant
metabolism and functions, such as photosynthesis and carbohydrate
distribution, and give good results in terms of yield and fruit quality of
organically grown cherimoya (Bonaventure, 1999). Further research results
are expected to appear on this subject in the coming decade, due to the
increasing consumer demand of pesticide-free and organic produce.
10.3.6 Irrigation
The selection of the appropriate irrigation system is directly related to three
main factors: technical, economic and human (Silva et al., 1996), within
which, there are several critical aspects. Water management (availability in
quantity and quality) and its infiltration, slope of the land, plant phenology
and climate are technical aspects. For instance, the sprinkler irrigation system
should be used in areas where water is not a limiting factor and where slopes
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