☰ Contents · Technology

Crops and greenhouses

Lessons 92–95 · 4 lessons · Sh. Sharipov, N. Muslimov, O. Tolipov, Q. Abdullayeva, O. Qo‘ysinov, V. Sattorov, S. Ahmadaliyev, M. Mo‘minova. Mehnat ta’limi (Labour Education / Technology), Grade 5. Sharq Publishing, Tashkent, 2015
95

Cotton-growing technology and process

Textbook: pp. 195–196
GoalKnow the cotton plant’s development stages and their dependence on temperature.
New words
cotton seed · chigittrue leaf · chinbargbudding (square formation) · shonalashflowering · gullash
Explanation

From seed germination to producing new seed the cotton plant passes 5 stages: emergence, true leaf formation, budding, flowering and ripening. For the seed to germinate the soil must be at least 10–12 °C, and germination speeds up at 20–25 °C. Seedling emergence depends on temperature: at a steady 15 °C 19–20 days, at 20 °C 8 days, at 25 °C 4 days. With enough warmth, moisture and air, seeds emerge in 5–8 days; when more than 50 percent of seedlings have appeared, full emergence is reached. The first true leaf appears in about 8–9 days at 15–16 °C and after 4 days at 25 °C. When 7–8 true leaves are out, a bud 3–5 mm across is seen next to the 5th–6th leaf. For flowering the daily mean temperature should be about 19–20 °C; in Uzbekistan cotton starts to flower in June. Also in the harvest work with adults and protect yourself from sun and dust.

Worked examples
At 15 °C emergence takes 19–20 days, at 25 °C only 4: a difference of about 15 days.
Of the five stages, three come before flowering: emergence, true leaf, budding.
Class activity

Observation: germinate cotton seed or a bean seed on damp cotton wool in a cup in class and record daily. Compare a warm and a cool place.

Practice
1
Between which two stages does budding come?
2
What is the minimum soil temperature for germination?
3
How many days for seedlings to appear at 20 °C?
4
Why do seedlings appear later when it is cooler?