Growth dynamics of the fruit of members of the Cucurbitaceae family

. In this article, the results of the research conducted to study the growth dynamics of the fruits of plants belonging to the Cucurbitaceae family, the fruit growth took place along a simple sigmoid curve: at first, the size and weight of the fruit increased exponentially, then this process slowed down, and it was given with an in-depth scientific analysis. It was noted that the ratio of fruit formation and ripening periods was 1:2 in "Uzbeksky 740" and "Margelansky 822" varieties of cucumber, and that the period of fruit formation in "Uzbeksky 452" and "Kuzybay 30" watermelon varieties was slightly longer than its ripening period.


Introduction
The beginning of ontogeny is called the embryonic period [8], because it mainly consists of the formation of the embryo, then the seed and the fruit.Fruiting, the transformation of a flower into a fruit, occurs with the drying and shedding of the pistil (and sometimes the stamens) and subsequent growth of the ovary [11].
The flowers of the representatives of the family are large and rich in nectar.Therefore, in July-August, apiaries can be transported to agricultural crops: melon, watermelon, cucumber and pumpkin [2].This has a positive effect on the process of pollination of plants.
Sometimes the growth of the ovary begins to accelerate until the pollen tubes reach the ovaries [6].Fruiting is one of the main stages in the life cycle of a plant.However, A. Leopold noted, little is known about its biology and physiology.The ovary in cucumber begins to grow before pollination, but after pollination, its growth increases dramatically [10].
The fruit of representatives of the Cucurbitaceae family is pepo.In the pericarp of pepo fruit, there are vascular bundles, and sometimes an exocarp consisting of a fleshywatery or other tissue passed through the sclerenchyma, and an endocarp in the form of an inner epidermis.Mesocarp is divided into several histological zones: lower epidermis, sclereid layer, parenchyma layer.Based on the anatomical structure of the pericarp, 8 carpohistological types have been identified in the Cucurbitaceae family [12].
The formation and ripening of the fruit of members of the Cucurbitaceae family is closely related to the neoformation of its components, first of all, the formation and ripening of seeds.In representatives of the family, the growth and development of the fruit consists of 2 periods: formation and ripening [1].
The growth and development of the pepo fruit occurs due to the growth of the ovary or nodule.These processes have not been sufficiently studied [5,7].
The fruit grows by cell division and multiplication before mitosis [19].Usually, the initial growth is due to an increase in the number of cells, which begins before the blooming and continues after the flower is pollinated.The duration and transition time of these two growth phases are different.The final size of the fruit is determined by the size and number of individual cells.
Maturation is a process associated with metabolic activity and requiring energy expenditure [6].The low temperatures observed in melons crops can be explained by the retardation of fruit ripening, the suppression of reactions that provide energy for the change of substances associated with its ripening [10].
Effect of irrigation regimes and mineral fertilizer rates on watermelon fruit ripening is high.It should be noted that 7-10 days before the start of harvesting watermelons, irrigation and mineral fertilizer should be stopped [20,21].
Knowing the time of fruit formation and ripening makes it easier to select parental forms to create early or medium and late forms [4].
Phenological and morphological observations were made every 5 days from the appearance of seedlings until the end of the growing season.During the growth period, the number of male, female and bisexual flowers and fruits on each plant was counted.
Biology of bloom and pollination of representatives of the family was studied according to the method proposed by scientists [14,15].We studied the bloom period of plants, the order of bloom, the diurnal rhythm of bloom, the structure and blooming mechanism of flowers, the quality of pollen, the types and methods of pollination.
The duration of blooming of the first flower and the whole plant was determined by labeling during the blooming period -from the first flower to the last flower blooming.The diurnal rhythm of blooming was studied by quantitative counting of flowers bloomed every 2 hours from 06:00 to 22:00.At the same time, air temperature and relative humidity were measured with an aspiration psychrometer.The seasonal dynamics of blooming was observed in plants with 5-10 counts every 3 days, taking into account the number of bloomed male, female and bisexual flowers.The color of flower parts, fruits and seeds was determined according to the color scale [3].
To study the dynamics of fruit growth, the opening date of the fruit-bearing flower was determined, and then the length, width, and weight of fruit-forming ovaries were measured at 10:00 AM every 2 days until the fruit was fully ripe.Biometric measurements were carried out on 5 labeled plants.
To study the quality of seeds at different maturity levels, the material was taken from typical fruits of 20, 30, 40, 50 days.Age was determined at 10, 20 and 30 days of ripening after pollination.Seeds were separated from one group of fruits on the day of collection.The rest were taken in a utility room at an air temperature of 18-26 °C and a relative humidity of 45-65%.
Seed productivity determined with modified methods [16,18].The number of formed and bloomed flowers per plant, the number of mature and ripe fruits, the number of ovules per bud, and the number of ripe seeds per fruit were taken into account for the analysis of seed yield.Based on the listed elements of seed yield, 2 main indicators were determined: potential seed yield (PSY) and actual seed yield (ASY).Based on the ratio of these indicators, the percentage of fertilization was determined, that is, the number of ovaries that turned into seeds.

Results and discussion
In our research, we studied the growth dynamics of the fruits of members of the Cucurbitaceae family.For this purpose, the day when the fruiting flower bloomed was determined, and the length and width of the fruit were measured in 5 labeled plants from the next day.Measurements of the first and second fruits were made every 2 days at 10:00 a.m. until full fruit maturity.
Intensive growth of the fertilized ovary began on the 2nd day.In the first and second weeks, its growth in length and width was observed, and then the rate of growth gradually slowed down.
Table 1 shows the dynamics of fruit growth of 3 varieties of melons, which represent 3 species and differ sharply according to the morphobiological characteristics of the fruit: "Khandalak kokcha 14" (M.chandalak) -early-ripe, round fruit; "Ich-kizil krupnoplodnaya" (M.ameri) -medium-ripe, elliptical fruit; "Kuy-bash 476" (M.zard)late-ripe, ovoid fruit.The growth of the fruit that appeared in them happened in different ways, but in the initial stages, the fruits of all varieties developed very strongly.
It should be noted that the time of formation of the first and second fruits did not coincide.The formation of the first fruit lasted from 21 to 32 days, and the formation of the second fruit lasted from 20 to 30 days.This period is 21-29 and 20-28 days in early melon varieties (M.chandalak), 29-33 and 26-29 days in mid-early-ripe varieties (M.ameri), and 27-30 and 26-30 in late varieties (M.zard).In wild melon (M.agrestis), the fruit formed in only 13-14 days (Table 1).
Thus, we determined the following: 1) in early-ripe varieties (Khandalak kokcha 14, Makhalliy sariq khandalak, Obi navvot) the period of fruit formation takes almost 2 times longer than the period of ripening; 2) in medium-ripe (Kokcha 588, Ich-kizil krupnoplodnaya, Shakar-palak 554) varieties, the period of fruit formation does not exceed the period of ripening; 3) in late-ripe varieties (Zar Gulobi, Kuy-bash 476, Umirvaki 3748) the ripening period is longer than the formation period; 4) in wild melons (M.agrestis), the periods of fruit formation and ripening are almost the same.It is noteworthy that the Melo zard species is much superior to other species in terms of fruit formation and duration of ripening periods.Wild field melons are far behind cultivated species in terms of these indicators.
We comparatively studied the dynamics of fruit growth in 4 representatives of the Cucurbitaceae family, which differ sharply in the morpho-biological characteristics of the fruit.In all representatives of the Cucurbitaceae family, the fruit grew more intensively in the early stages (1-2 weeks).
In our research, we observed that after 3 days of fruit formation, the fruit of the "Kuzybay 30" variety of watermelon reached 280-290 g.In 13-15 days, under optimal conditions, the growth rate of the fruit was directly related to age.The correlation coefficient between fruit weight dynamics and its age is r = 0.77 ± 0.20.Many years of observations have shown that this equation can be used in practice for a certain variety under normal climatic conditions.The error in planned calculations does not exceed 16%.The deviations are related to changes in the average daily fruit growth, which changed significantly in the first 30 days.During this period, the average daily fruit weight gain in the watermelon variety "Uzbeksky 452" was 155.6 g (from 2 to 400).
Average daily fruit weight gain in the first 12 days after fruit formation was 221.5 g (range 83 to 400).Correlation coefficient r = 0.97±0.03.Variation coefficient V =8.3%.The correlation is very close: r= 8.4.From the fifteenth day, the average daily growth was inversely correlated with the age of the fruit.
Similar indicators were also observed in the experiments conducted by M.Y.Veselovskogo (1972) with different varieties of watermelon in the Astrakhan region.With the beginning of the physiological ripening of the seeds, the growth rate of the fruit decreases.The early-ripe variety, the earlier the decline in average daily fruit growth begins.In the process of growth, the mass of the melon fruit also changes directly depending on the age.Correlation coefficient between fruit weight and age for melon variety "Kokcha 588" is r = 0.98 ± 0.21 (close relationship, K = 21.0%,t = 5.4).The fruit of the "Kuy-bash 476" variety of watermelon made 10% of the final mass in the first 10 days, 33% in 20 days, the average daily weight of the fruit in the first 10 days was 80 g, in the next 10 days -115 g.After 40 days, the daily growth decreased dramatically.The fruit of the "Kokcha 588" variety of melon collected 17.5% of the maximum mass in the first 10 days, and 31% in the 20th day.The average daily growth in the second ten days was 57 g, and the growth in the third ten days was 141 g.It should be noted that the fruit of this variety continued to grow even later.
Melon variety "Kokcha 588" reached a constant mass 25 days after the fruit began to form.The fruit of the melon variety "Kuy-bash 476" continued to grow until the 40th day.During this period, the average daily fruit growth of the "Kokcha 588" variety was 72.8 g, and this indicator was 93.8 g in the "Kuy-bash 476" variety.The daily growth of the fruit is closely related to the growth of the seeds.
In watermelon varieties "Uzbeksky 452" and "Kuzybay 30", fruit growth was visually recorded 2-4 days after the beginning of fruit formation.Unlike melon, all varieties of watermelon had the same growth rate for 30 days, and after 30 days the ripening period began.The results of the morphometric analysis during the formation of the watermelon fruit showed that its growth was carried out uniformly.The ovary begins to grow immediately after the formation of the fruit.During the first 2-4 days after the flower is pollinated, the fruit grows slowly.Then its growth rate increases sharply.The most intensive growth is observed after 5-20 days.During this period, the mass of the fruit increases dynamically.During the ripening period, the intensity of fruit growth is sharply weakened, and then it stops.
Watermelon grows very fast.For example, in the "Uzbeksky 452" variety, the fruit weight was 1.20 g after 5 days, and 4.4 kg after 50 days.In the first 20 days, 60% of the final mass (2.4 kg) was collected.In the variety "Uzbeksky 452" the maximum number of seeds from the fruit was observed at the age of 40-50 days, in the variety "Kuzybay 30" at the age of 50 days (Table 2).
In the studied 2 varieties of cucumber, the fruit grew quickly and the seeds ripened in 12-15 days.First, it grew intensively in length, then in width.The growth of cucumber fruit lasted 15-20 days.Later, its length did not increase visually.Nevertheless, with the increase in the age of the fruit, its mass increased accordingly.Thus, in the variety "Uzbeksky 740" 5 days after the appearance of the fruit, its mass was 20 g, after 20, it was 184 g.After 20 days, the growth of the fruit stopped, but the accumulation of its mass continued.For example, the weight of the "Margelansky 822" variety was 300 g after 20 days of fruit appearance, 398 g after 30, 425 g after 40, and 450 g after 50 (Table 3).Thus, the growth of the fruit in the cucumber lasted 20 days, this is the period of formation.After that, the ripening period, which lasts 35-40 days, began.During the ripening period of the fruit, its weight increased, for example, it lasted up to 40 days after the appearance of the fruit in the "Uzbeksky 740" variety, and up to 50 days in the "Margelansky 822" variety.After fruit weight gain stopped, ripening continued.The ripening period of pumpkin varieties "Ispanskaya 73" and "Palov kadu 268" was characterized by an increase in the amount of carbohydrates and dry matter in fruits and seeds, a decrease in moisture content, and a gradual drying of the peel.The maturity of the fruit ends with the complete loss of metabolic connection with the plant body.
In both varieties of pumpkin, the period of fruit formation and ripening lasted longer than that of melon, watermelon and cucumber.For example, in the variety "Palov kadu 268" the fruit reached its maximum size in 50 days.It was observed that it grew up to 10 cm 5 days after the appearance of the fruit, 15 cm after 10 days, 40 cm after 30, and 50 cm after 40-50.The diameter of the fruit was 10 cm after 6-8 days, after 12 days it was 30 cm.
Its weight increased in parallel with the increase in duration of fruit growth in both varieties.So, after 5 days, the appeared fruit was 9.2 ± 0.1 kg in the "Ispanskaya 73" variety, and after 10 days it was 1.2 ± 0.23 kg.It took more than 60 days for the fruit to reach maximum weight (4.3 ± 0.78 kg).By this time, its varietal characteristics were fully formed.The proportion of seeds increased with age.A similar situation was observed in the variety "Palov Kadu 268" (Table 4).
In B. melanocarpa, 2-3 days after the opening of the female flower, the growth of the ovary began, after 10-12 days, the diameter of the fruit reached 7-8 mm and the growth stopped.When the fruit turns green, the ripening period or the milky stage begins.At this stage, the seeds have not yet formed, the fruit is spherical, juicy, green, with black dots on the skin.In this case, it was 35-40 days.
The fruits of studied varieties of watermelon and pumpkin are spherical.At all stages of formation, they grew equally in the longitudinal and transverse direction.The fruits of "Kokcha 588" and "Kuy-bash 476" varieties of melons were elliptical and oval, the fruits of "Uzbeksky 740" and "Margelansky 822" varieties of cucumbers were oblong, and the fruits of "Palov kadu 268" variety of pumpkin were elongated pear-shaped.In the first and second stages of growth, the ratio of longitudinal and transverse diameter of fruits was 1.6:1.0.The formed fruit receives nutrients from other parts of the plant, primarily from the leaves that are close to each other, and then less nutrients reach the formed fruit, which limits their growth rate and size.Apparently, therefore, a sharp difference in the size and growth rate of the 1st, 2nd and 3rd fruits of the varieties we studied was observed.
Many fruits, including pumpkin, grow at a high level due to the development of intercellular parenchyma.He studied the main feature of morphogenesis in fruit development -the polarity of division distribution and cell enlargement.When the direction of growth changes, the ratio of the length of the fruit to the diameter has been determined (Matienko, 1967).Thus, during the periods of fruit formation and maturation, integration occurs in the development of ovaries, endosperm and embryo, on the one hand, and seeds and fruits, on the other.After the end of fruit formation, characteristic quality changes in melons, watermelons, cucumbers and pumpkins -maturity begins.The fruit of polys crops becomes soft when ripe (cucumber), changes color and taste (melon), dries and hardens (pumpkin).Wild melon fruit dries up and turns brown-black.

Conclusion
In plants belonging to the Cucurbitaceae family, fruit growth occurs along a simple sigmoidal curve: at first, the size and weight of the fruit increase exponentially, then this process slows down.In "Uzbeksky 740" and "Margelansky 822" varieties of cucumber, the ratio of fruit formation and ripening periods was 1:2.In "Uzbeksky 452" and "Kuzybay 30" varieties of watermelon, the period of fruit formation was slightly longer than its ripening period.Seed yield and percentage of seeds are not the same in members of the Melo, Cucumis, Citrullus and Cucurbita genera of the cucurbit family.Melons, cucumbers, watermelons and pumpkins are characterized by energy sterility.

Table 1 .
Melon fruit formation and period, days