In 1986, Indian Institute of Horticultural Research, Bangalore initiated work on evolving a less seeded, very sweet custard apple variety with better shelf life. Hence, a large number of inter- and intra-species annona hybrids were developed evaluated, and a hybrid by name ‘ArkaSahan’ was released in 1997. Fruits of ArkaSahan are remarkable for scarce small seeds (9/100g fruit weight), sweetness (>32°B: 22.8% total sugar), and slow ripening (5-6 days). The pulp is snow-white, mealy and juicy with a mild pleasant aroma. Nutritionally, a 100g pulp of ArkaSahan contains 2.49g crude protein, 42.29mg phosphorus and 225mg calcium compared with 1.33g, 17.05mg and 159mg respectively, in common custard apple. It is an inter-species hybrid developed by hybridizing Island Gem (atemoya) and Mammoth (custard apple).
The hybrid produces large number of self-fertile flowers. As in other annonas, few flowers of ArkaSahan (about 1-2%) develop into fruits owing to male and female structures maturing at different time, besides limited insect and wind pollination. Hence the cropping potentiality will not be realised if relied only on natural pollination. To supplement this, hand pollination, which is quite simple, fast and economical was worked out to achieve not only higher productivity, but also large sized symmetrical fruits.
In 2003 and 2004 hand pollination was attempted during different period of the day using five pollen sources. Better result was obtained when hand pollination was effected in the morning from 6.00 to 9.30. Use of custard apple (sitaphl /sarifa) pollen rather than that of ArkaSahan gave excellent results.
As many as 80% of the pollinated flowers produce fruits that will stay until harvest, and which as compared to open pollinated fruits weigh about 90% more (450-500g) and possess almost uniform shape with no loss in edible fruit attributes. Since ArkaSahan flowers are big hand pollination is relatively easy and fast. One can pollinate 150-200 flowers/ hour. Eight years onwards a tree of ArkaSahan can produce 40-45 kg fruits, hence in each tree about 150 flowers should be hand pollinated to achieve an expected yield of 25 tonnes/ha. Fruits developing from artificial pollination will command premium price in the market making the practice commercially viable.
Fruits of ArkaSahan are remarkable for scarce small seeds (9/100g fruit weight), sweetness (>32° B: 22.8% total sugar), and slow ripening (5-6 days). As in other annonas, few flowers of ArkaSahan (about 1-2%) develop into fruits owing to male and female structures maturing at different time, besides limited insect and wind pollination. Hence the cropping potentiality will not be realised if relied only on natural pollination. To supplement this, a simple artificial hand pollination was worked out by testing different pollen sources. ArkaSahan fruits developing from pollen of Annonasquamosa (sitaphal or sarifa) were by far better than those produced from other pollen sources including natural set in respect of fruit set, size and shape. Very high fruit set of 86 per cent was obtained from the pollen of sitaphal while that of ArkaSahan pollen and natural set was 55.2% and 1.4% respectively. Moreover, the fruits emerging from sitaphal pollen were of big size (432g) in contrast the natural set fruits weighed on an average 206g. But the other pollen sources viz., A.reticulata, A.atemoya, A. cherimoya did not give satisfactory results.
Hand pollination should be effected in the morning hours before 9.30, as described below.
- Collect pollen of custard apple (sitaphal) in a plastic cup from the previous day opened flowers.
- Place the cup in the shirt pocket and dip a clean dry paintbrush (No. 2 or 3) into the cup.
3.Using the pollen coated brush evenly smear the pollen on the stigma of ArkaSahan flowers.
Hand pollination is a simple and fast technique that results not only in good fruit set but also produces big size, attractive uniform shape fruits with no loss in edible attributes. Thus fruit yield can be significantly increased by artificial pollination. A tree of ArkaSahan can produce 40-45 kg fruits eight year onwards, hence in each tree about 150 flowers should be hand pollinated to achieve an expected yield of 25 tonnes/ha. Fruits developing from hand pollination will command premium price in the market.
Fruits obtained by hand pollination