Management measures during jointing and panicle growth of rice

The jointing and long panicle stage refers to the period from jointing and young panicle differentiation to pre-heading, and the medium rice generally lasts for 25-36 days.

1. Growth characteristics and appearance of jointing and panicle stage

The main results are as follows: (1) the growth characteristics during this period, on the one hand, take the stem elongation as the center, complete the growth of the last few leaves, roots and other vegetative organs, on the other hand, carry on the reproductive growth centered on the differentiation of young spikes. During this period, some tillers gradually died, and the total number of tillers decreased compared with the previous period, so it was an important period for tiller protection and panicle increase. Because the young panicle development is mainly floret differentiation, and the differentiated spikelets can not bear fruit completely, this period is not only the key period for increasing flowers and grains, protecting flowers and grains to determine the number of grains per panicle, but also laying the foundation for grain filling. Due to the intensified growth of various organs, the dry matter accumulated in the upper part of the mainland in just one month accounts for about 50% of the total dry matter of rice in its lifetime. Therefore, this period is a period in which rice needs more water and fertilizer, and it is also the most sensitive period to external environmental conditions. Because the physiological metabolism of rice at this time is mainly from nitrogen metabolism to carbon, and nitrogen metabolism is flourishing, it not only requires rich nitrogen nutrition to supply the last clover and surface root growth and stem elongation, but also must accumulate enough carbohydrates. and ensure that it is transported to the panicle to meet the needs of panicle development. The main direction of high-yield cultivation field management is to protect tillers and attack panicles and strive for large panicles. That is to make the early tiller die to increase the panicle rate, the stem is stout, the basal Internode is short, enhance the lodging resistance, prevent the leaf from growing too long, promote the spikelet differentiation, reduce the spikelet degeneration, and achieve the purpose of large spike and multi-grain.

(2) the change of leaf color in growth phase: it is required to appear "one yellow" at jointing to "two black" at booting, and then fade slightly when heading fast, and appear "two yellow". The suitable closure period is when the flag leaves are exposed to the tip, so the leaves have been fixed, and the basal 4 and 5 segments have basically been elongated and filled, even if the shade has little effect. Leaf length: the last three leaves should gradually become shorter, thick and erect, the sword leaf tip and ear tip are equal or slightly higher after heading, and the flag leaves grow and droop is a sign of excessive fertilization and overgrowth. The leaf area coefficient reached the maximum from booting to heading stage, and then decreased gradually. The optimum leaf area coefficient of high-yield rice varies with variety, plant type, leaf growth posture and cultivation management level. The maximum leaf area coefficient of medium dwarf conventional rice in Sichuan, Guizhou and Yunnan is as high as 6: 7, and that of hybrid rice is as high as 8 (Yunnan medium japonica rice is as high as 8: 8.9).

In a word, the growth and appearance of the jointing and panicle stage requires that the rice plant grows healthily, the base is thick and round, the leaf is straight and green, the length of the top leaf is moderate, and the root system develops in depth.

two。 Field management measures

The main results are as follows: (1) the fertilizer applied skillfully from the beginning of young panicle differentiation to heading is called panicle fertilizer, and the application effect varies with the poor environment. Improper application not only failed to increase flowers and grains, but also resulted in a high rate of empty grain and a decrease in yield. Therefore, the application of panicle fertilizer should be comprehensively considered according to the expected requirements of variety, climate, soil, high-yield structure and ideal growth. General early-maturing varieties can not be applied, but for general mid-late-maturing hybrid rice, panicle fertilizer should be applied on the basis of early application of tiller fertilizer, especially for Sha Tian with low fertility and weak fertility. For slow growth in the early stage, yellowish leaves at jointing stage, no dew in the leaves in the morning, flower-promoting fertilizer should be applied at noon when the leaves are straight, and flower-protecting fertilizer should be applied if the "two black" is not significant at booting stage, so as to improve seed setting rate and promote large panicle. Panicle fertilizer should be combined with nitrogen, phosphorus and potassium.

(2) reasonable water pipe and long panicle stage is the period when rice needs the most water in its life. To ensure that there is no shortage of water and no drought, the general field should maintain a 30 mm water layer, so that the absorption and movement of nutrients by rice plants can be smooth, the maximum photosynthetic efficiency can be maintained, and spikelet differentiation can be promoted. Reduce floret abortion. In cold and high temperature areas, the temperature regulation of the water layer can be properly deepened to make the soil temperature more stable and avoid affecting panicle differentiation due to the change of air temperature. However, we should also pay attention to the aeration conditions of the soil in order to maintain root activity and prevent premature senescence.

(3) the main pests in this period are stem borer, rice bract insect, rice leaf roller and rice planthopper, as well as armyworm, and the main diseases are sheath blight, bacterial blight, rice blast and so on.