Cultivation Guide for Choy Sum Variety Series
1, Requirements of Circumstance Condition
1.1, Temperature
The choy sum will
develops successfully when the mean temperature of month is 11-28 degree
celsius, but the range of proper temperature is different for different growing
period. For germination and seedling stage, the proper growing temperature is
25-30 degree celsius, and under this temperature it only takes 5-7 days from
germination to unfold of cotyledon, and 9-11 days from the exposure of main
leaf to the unfold of the 5th main leaf, taking 14-18 days for the whole
seedling stage. The gowing period of leaf is from the 6th leaf to bud stage,
taking about 10-21 days. From the flower-bud appearing stage to flowering-stalk
forming stage, the proper temperature is 15-20 degree celsius. The temperature
in early period is better to be higher, to promote the plant into vegetative
growth, and better to be reduced step by step when come to the reproductive stage to benefit the formation
of flowering-stalk.
1.2, Illumination
The time of sunlight do
not notedly impact the appearance of flower bud and blossom, but adequate
ilumination will benefit the accumulation of assimilating substance and promote
the formation of flowering stalk.
1.3, Fertilizer and
Water
The fertilizer and water
have close relations with the formation of flowering stalk, especially around
the appearance of flowering bud, the abundance of fertilizer and water will
benefits the formation of flowering stalk. After the main flowering stalk in
formed, supply fertilizer and water timely, to promote the formation of side
flowering stalk, prolong harvest period and increase yield.
2, Time and Mode of Cultivation and Selection of Variety
2.1, Cultivation Season and Mode
In northern areas, for
cultivation in sunlight greenhouse in Spring and Winter, and plastic high
tunnel, it is intercropped with cucumbers, tomatoes and other main crops, and
also can be cultivated alone in shed room, more commonly in suburb near big
city such as Beijing and Tianjin Yangtze
River valley, select early maturity variety to sow directly in
open field from Apr. to Aug., with 35-40 days of growing period, and enter
market from May to Oct. It’s better to select middle maturity variety from
Spet. To Oct., harvested in 40-50 days after sowing and supply for market from
Oct. to Jan, next year. From Nov. and Dec. to May next year, sow separately
step by step, harvested in 45-55 days after sowing and enter market from Dec.
to Apr. next year In succession.
2.2, Selection of Variety
The varieties of Choy
Sum fall into early maturity ones, such as No. 49 Sweet Choy Sum and Short-Foot
45-Days Choy Sum, middle maturity ones such like Oil-Green Thick Choy Sum and
Selected Oil-Green Choy Sum, and late maturity ones like Green-Treasure
Oil-Green 70-Days Choy Sum and Big Oil-Green 80-Days Choy Sum.
3, Selection of Field and Management of Seedling Stage
3.1, Selection and Preparation of Field.
The Choy Sum is more fertilizer-resistant,
select loam or sandy loam which has fertile soild and is rich in organic
substance to cultivate on. Before sowing, plough the field deeply and sun the
ridge, supply adequate base manure, prepare field carefully to make the surface
of ridge in turtle shape, without big holes and crack. Generally, the ridge is
1.5-1.7m wide including ditches, and 20-30cm high.
3.2, Cultu
re of Strong Seedling
Both direct sowing and
culture of seedling are suitable. The seedbed should be ploughed deep and sun
to white, supply organic manure mainly, and assisted by fertilizer. Supply
fertilizer mainly by base manure, assisted by top dressing. Each acre supply
6000kg of organic manure, and 60kg of calcium-magnesium-phosphate fertilizer,
as base manure. When the first main leaf unfolded, top dressing thinly. Top
dressing 1-2 times in seedling stage. Control seedling stage in 12-25 days.
For direct sowing, using
strip planting or broadcasting, more applied in high temperature and rainy
season. In the Autumn, Winter and low temperature of early Spring, the culture
of seedlings is more common. Broadcast 2.4-3.0kg of seeds per acre, with 20-30
days of seedling stage.
Because the early and
middle maturity varieties are sensitive to temperature and develop speedy,
attention to prevent early maturity in seedling stage. The late maturity
variety is more strictly requires temperature. Sow on time, to benefit the
plant to turn into reproductive growth in time. Meanwhile, the quantity of
sowing seed is different. For Autumn and Winter culture of seedling, each acre
costs 2.4-3.0kg of seeds, and is increased to 3.0-4.5kg in Spring and Summer.
After germination, thin the seedlings in time when the cotyledon starts
unfolding. Accompanying with growth, thin for 1-2 times. As to enlarge standing
area, thin seedlings by the distance of 14cm when there are 4-6 pieces of
leaves for thin early maturity variety, by distance of 16-17cm when there are
6-8 pieces of leaves for middle maturity variety, and by distance of 20cm when
there are 6-8 pieces of leaves for late maturity variety. Timely top dressing
and watering. Generally when the first main leaf unfolds, top dressing once,
and pay attention to the adjust and control of temperature and humidity. It's
suitable for transplanting when the seedling outgrows 4-5 pieces of leaves.
Therefore, the seedling stage should not be over 12-20 days in Summer and
Autumn, and are suitable be 18-25 days
in Winter.
4, Field Management
4.1, Covering of Shading Net
The shading net can be used for cultivation
of choy sum in Summer and Autumn. Cover with cooling gauze after sowing , to
play a part in moisturizing, and preventing plant from burning by high
temperature and soil from hardening, so as to benefit germination, trim
seedlings and full standing. Remove the shading net promptly after germination
to prevent excessive growth. If the cultivation is in high temperature and
rainy season, for to avoid adverse weather from impacting the growth of choy
sum, uncover the shading net after germination, and raise it to be 80-100cm high
to build up small flat shed to fight against heat and rainy, properly covered
for 10-15 days. If for transplanting after culture of seedling, cover for 5-7
days after transplanting. Must avoid covering for whole growing period. It is
better to choose shading net which has 45% of shading rate and is in
silver-grey color.
4.2, Management of Fertilizer and Water
For early maturity and oil-green choy sum, as
the plant grows speedy with short growing period, it is suitable to supply
adequate base manure. Generally, supply 9000-12000kg of pig manure or 4500kg of
fowl manure, and 120-180kg of compound fertilizer per acre, mixed with soil
fully. Top dressing in growing period in time. The top dressing is mainly by
quick-acting nitrogen fertilizer in early period, and assorted with phosphate
and potash fertilizer in middle and later period, so as to benefit the increase
of yield and quality. To promotion of seedling, water once thin liquid dung or
18-30kg of urea per acre in the first main leaf. Aling with thining in trefoil
stage, top dressing by 6000kf of 20% human dropping, or 30kg of urea mixed with
60kg of compound fertilizer per acre, and top dressing once each week until 8
days before harvest. Top dressing 3-4 times in whole growing period. When
manuring, avoid dropping fertilizer on flower bud to prevent from causing
rotten bud.
5, Harvest
When the flowering stalk grows to be or
almost be in the same level with plant leaf, harvest in time. The timely
harvest will increase the quality and yield. For early maturity variety, if
only to harvest chief stalk, the harvest node should be in the base of the
talk. For middle and late maturity variety, as the side bud germinates easily,
reserve 2-3 pieces of leaf when harvest chief stalk for the germination of side
stalk. It’s better not to reserve too many leaves, otherwise the side buds will
germinate too many to keep thick stalk and quality. The shape standard of high
quality flowering stalk is that: thick flowering stalk, thin node, less and
thin leaf, and beginning of flowering on top.
6, Control of Disease and Insect Pests
6.1, Disease
The main diseases includes anthracnose ,
soft rot and virus diseases.
In early attacking period, supply
1500 times of 50% sporgon WP, 800 times of 80% thiram(ziram) WP, or 600 times of 70% thiophanate methyl WP for 2-3 times in 7-10 days of interval.
Use 800 times of 3% Zhongshengmycin SP, or 4000
times of 72% agricultral streptomycin SP in the early attacking
period. Control for 2-3 times in 7-10 days of interval.
In early attacking period, spray
600 times of 3.85% bingdubike aqueous solution (0.1%ribavirin+1.25%copper
sulfate +0.1%triacontanol AS), or 1000-1500 times of 1.5% zhibingling EC(1%
dodecyl sodium sulphate+1.4%copper sulfate+0.1%triacontanol WP) for control.
6.2, Insect Pests
The main
insect pests includes yellow striped flea beetle, diamondback moth,
cabbageworm, Spodoptera litura, and so on.
Use
1500-2000 times of 40% chlorpyrifos EC, or 1000-1500 times of 45% malathion EC,
to spray from outer around to center field.
In the
acme of second age larva, spray 1000 times of BT WP and 3000 times of Spinosad EC, or 3000 times of
1.8% abamectin EC, or 1500 times of 20% chlorfenapyr EC for control. The
pesticide mentioned should be used alternately.
In the
hatching acme of egg, use 1000 times of BT WP to spray for control. In the acme
of low age larva, spray 2500-5000 times of 2.5%
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