STUDY ON RAISING OF RICE CROP IN INDIVIDUAL PLOT FOR OBSERVING GROWTH PHASES AND STAGES
We are the students of B.Sc. Ag (Hons) level-1 semester-1 raised crop (rice) for observing its growth phases and stages. The detail cultivation procedure of the crop has been given below-
Three local varieties were selected for cultivation. These were-
Seedling Raising :
Healthy seeds were selected by specific gravity method and then sprouted by immersing in water in bucket for 24 hours. Then seeds taken out of water and kept thickly in gunny bags an the sprouted seeds were sown in the nurserybed on .........................
Land preparation :
The main land was puddled thoroughly by Ploughing and cross plunging with a country plough and subsequently leveled by laddering. Due to lack sufficient land area, the total students of B.Sc. Ag (Hons) L-1, S-1, was divided into three groups and each of these groups was allocated ...................... area for transplantation.
Seedling uprooting :
The students themselves uprooted the seedling of one variety by one group them.
The seedling of 47 days old of different varieties were transplanted in the three different plots on ¾ . The spacing of planting was 25 cm for line to line and 15 cm for plant to plant
distance . Three seedlings were planted in one hill.
The land was fertilization as and when necessary.
Intercultural operations :
The intercultural operations were done as and when necessary.
OVSERVATION OF GROWTH PHASES AND STAGES OF RICE PLANT
The life cycle of rice plant may be divided into the following three phases:
1. Vegetative phase : From germination to panicle initiation.
2. Reproductive phase : From panicle initiation of flowering.
3. Ripening phase : From flowering to maturity.
These phases may be subsequently divided into different growth stages.
Vegetative phase :
This phase begins with the seed germination, which is signified by the emergence of radicle or coleoptile in the germinating embryo. During the vegetative phase, the plant undergoes the following stages:
I. Seedling stage : This stage follows seed germination and the seedling develops germinal and lateral roots. Seedling stage is generally considered from germination until the plants develop the fifth leaf. During this stage, the seedling absorbs food from the endosperm.
II. Transplanting stage : Only the transplanted rice plants undergo this stage. It covers the period from uprooting of the seedling to full recovery. Direct seeded rice plants do not undergo through this stage.
III. Tillering stage : This stage starts with the appearance of the first tiller from the auxiliary bud in one of the lower most modes. The number of tillers increases, at a point more rapidly (active tillering stage), until the maximum tiller number (maximum tillering stage) is reached. Then some tillers die, the number of tillers declines and levels off. The plant stops tillering after the tertiary tillers have been produced.
Reproductive phase :
During the reproductive phase, the plant undergoes the following stages :
I. Panicle initiation stage : The reproductive phase begins before reaching the stage of producing maximum number of tillers, at about the time of the highest tillering activity or thereafter. This phase is marked by the initiation of the panicle primordial of microscopic dimension on the growing shoot.
II. Booting and internode elongation stage : As the young panicle develops, It becomes visible to the maked eye in a few days. This marks the beginning of the booting stage.
The time of occurrence of internode elongation stage differs among varieties. With late maturing varieties, the accelerated elongation of the upper internodes may begin considerably earlier than the reproductive phase. With early maturing varieties, elongation may begin after panicle initiation.
III. Heading stage : This stage is marked by the emergence of panicle tip out of the flag leaf sheath. Emergence continues until 90% of the panicles are out of the sheaths.
IV. Flowering stage : Flowering or blooming or antheis begins with the protrusion of the first dehiscing anthers in the terminal spikelets on the panicle branches. Flowering continues successively until all spikelets in the panicle bloom. Polination and fertilization then follow.
RIPENING PHASE :
The rice grain develop after pollination and fertilization. Grain development is a continuous process and the grain undergoes distinct changes before it fully matures.
I. Milk stage : The contents of the caryopsis are first watery but later turn milky in consistency.
II. Dough stage : The milky caryopsis turns into soft dough and subsequently into hard dough.
III. Maturity stage : The individual grain is mature when the caryopsis fully developed in size and is hard, clear and free from greenish tint. This stage is completed when more than 90% of the grains are fully ripened.
Importance or insignificance of studying growth stages:
Crop growth phases provide indicators for crop management, and provide selection in crop improvement programs. Farmers and researchers use these knowledge’s of crop growth stages in developing crop management models. These models predict cultivar growth stages within the limits of yearly weather conditions and facilitate improved liming of cultural practices. Grain yield results from developmental processes that are synchronized with plant growth stage in rice, the division of yield into four yield components reflects the interdependence of yield with sequential plant development. Yield potentials are realized when all components are optimized. Yield constraints can be evaluated by identifying which of the components are limiting. Yield improvement in subsequent crop years can then be addressed through improved management or plant breeding relationship of yield components to growth phase.
Relationship of Yield Components to Plant Growth Phase:
Panicles per unit area (panicles/m2)
Vegetative phase, Number of panicles reflect plant vigor, tillering density, soil fertility, and flood depth.
Number of Spikelets per panicle
Reproductive phase, All potential spikelets are formed during panicle differentiation.
Percentage of filed grains (% filled, or % sterile, at maturity)
Reproductive phase, Spikelets development is sensitive to environmental factors. Either development or pollination failure precludes grain filling during the next phase.
Weight of filled grains (1000 seed weight0
Ripening phase. The weight of filled grains is determined by carbohydrate metabolism and partitioning. Grain weight can be reduced by metabolic failure.