PHOTOSYNTHETIC ACTIVITY OF BLUE LUPINE PLANTING DEPENDING ON THE ELEMENTS OF CULTIVATION TECHNOLOGY IN CONDITIONS OF UKRAINIAN POLISSIA

Abstract

Photosynthesis is an important life process of plants. Major factors, which create an optical-biological structure in culture planting, is the placement method and plant density. All other plant processes, in particular the process of mineral nutrition, are essential and effective in the case where they provide the formation and activity of the photosynthetic apparatus and the sustainable use of its products in the process of growth and development that is directly related to the yield formation.

The purpose of this article is to study of characteristics of leaf surface formation by plants of blue lupine, accumulation of dry substance, determination of net planting productivity of photosynthesis depending on variety, fertilizer, sowing method, seeding rate and the conditions of mineral nutrition, taking into account the effect of foliar application in different phases of culture development.

The experiment scheme included fertilization variants: without fertilizers, P₆₀K₆₀ – recommended in the cultivation area, N₃₀P₆₀K₆₀ and N₆₀P₆₀K₆₀ in combination with two foliar applications by nitrogen-phosphorus-potassium fertilizers with microelements in two terms (first – in the budding phase 10-45-15+0,5MgO+ME, the second – in the phase of beginning of seed formation 9-12-40+0,5MgO+ME). Crops are the predecessor. Varieties of blue lupine – Olympus, the Winner, Grozynsky 9, were sowed by the methods: a row (15 cm), skip one row (30 cm) and wide row (45 cm) with the seeding rate of 0.6, 0.9, 1.2 million pieces per hectare in three terms: the first term – time of sowing capability (РТР ‑ 5⁰С) (control), the second term – in 10 days after the first (РТР ‑ 8⁰С), the third period – in 20 days after the first (РТР ‑ 10⁰С).

It is noted that the area of leaves in the process of growth and development of blue lupine gradually increases is progress, reaching maximum values in the phase of beginning of seed formation. After this vegetation phase a reduction in leaf area is observed, due to the peculiarities of biology of culture development, in particular the redistribution and strengthened outflow of plastic substances from vegetative organs into seeds. This in turn causes the death and shedding of the leaves during maturation of the blue lupine seeds.

The largest area of leaf surface in the experiment, which was formed in the grain formation phase and depended on the fertilizer system, time and methods of sowing, was got by the experimenters after sowing 1.2 million pieces of seeds per hectare using the line method of sowing in the second period – 24.89–37,42 thousand м²/ha, smaller surface in the first period – 22.61–33.98 and the smallest one in the third – 20,39–30,05 thousand м²/ha; using skip one row method of sowing respectively 24,6-37,7; 22,30-34,10; 21,4-30,9 thousand м²/ha; and using wide row method respectively 19,20-12,14; 18,47-12,06; 15,28-12,05 thousand м²/ha.

According to the studies the size of leaf area depended not only on the number of the planted seeds but also on the phase of growth and development of plants. Sowing of 0.6 million seeds of blue lupine Olympus has ensured the formation of the assimilative surface of one sowing hectare in the twig phase of 5.25 thousand м²/ha, bud phase – of 10.96, bloom phase – 16,15 and seed formation 17,84 thousand м²/ha. Increase in seeding rate up to 1.2 million peaces contributed to the increase in leaf area from 7.31 thousand м²/ha in the bud phase to 24.89 thousand м²/ha in the phase of seed formation. Relation of varieties Winner and Grozynsky 9 was the same.

It should be noted that mineral fertilizers made a positive impact on the formation of leaf area. Due to phosphorus-potassium fertilizers (Р₆₀К₆₀) total leaf area of varieties increased from 19.37 thousand м²/ha at the minimum seeding rate to 28.53 thousand м²/ha with a maximum seeding rate, and the increase in the number of leaves on one sowing hectare  in comparison to not fertilized plants, at the same time, is respectively 1.53 and 2.25 thousand м²/ha. With the complete fertilizer N₃₀Р₆₀К₆₀ the leaf area increased by 4.5 thousand м²/ha with a minimum seeding rate to 6.26 thousand м²/ha at seeding rate of 1.2 million seeds. With double norm of nitrogen the leaf area increased by 5.65 thousand м²/ha at seeding rate of 0.6 million pieces to 9.97 thousand м²/ha at seeding rate of 1.2 million seeds. The Winner variety had a slightly smaller leaf surface area of 16.41-24,73 thousand м²/ha depending on seeding rate. With the introduction of mineral fertilizers the leaf area was growing to 17.78-34,27 thousand м²/ha.

The leaf surface of blue lupine of Grozynsky 9 variety was the largest and accounted 20,31–27.85 thousand м²/ha depending on seeding rate and 22.05–41,89 thousand м²/ha depending on the fertilizer system. However, the processes of influence of seeding norms and fertilizers in these varieties were similar to the Olympus variety.

It is established that the square size of the leaf surface differed on different experiment versions depending on the use of foliar application of water soluble NPK-fertilizer with microelements: the Olympus variety – from 0.03 to 0.10 in twig phase to 0.99-2,73 thousand м²/ha in the phase of seed formation,  the Winner variety – respectively 0.04 to 0.08 and 0.96-2.48 thousand м²/ha and the Grozynsky 9 variety –  from 0.06 to 0.12 thousand м²/ha in the twig phase and from 1.20 to 3.25 thousand м²/ha in the phase of seed formation.

The calculated leaf index shows that the greatest leaf surface – 2,39–2.92 м² per м² of sowing area – of blue lupine Olympus, the Winner, Grozynsky 9 was formed on a variant of the second sowing term with 30 cm space between rows and a seeding rate of 1.2 million peaces per 1 ha. These indexes exceeded the analogue versions of the first sowing term by 0.22–0.27 м²/м², and the third – by 0,43–0,53 м²/м².

The application of mineral fertilizers in the Р₆₀К₆₀ dose contributed to the growth of the leaf index in the phases of most intensive growth of leaf surface by 6–8 %, in N₃₀Р₆₀К₆₀ dose – by 18–20, N₆₀Р₆₀К₆₀ – by 25–40 %. The introduction of the foliar feeding by water-soluble complex mineral fertilizers with microelements contributed an added increase of leaf surface index depending on the conditions of mineral nutrition by 3–7 %.

Optimization of the conditions of mineral nutrition by mineral fertilizers in N_30-60Р₆₀К₆₀ norm in combination with two foliar feedings by water-soluble nitrogen-phosphorus-potassium fertilizers with microelements provides  the formation of the largest indicators of leaf area, photosynthetic potential and photosynthetic plant productivity of blue lupine, which in its turn creates the preconditions of its maximum productivity.