절엽의 시기 및 정도, 그리고 절엽 후의 시비가 수도의 생육 및 수량제형질의 변화에 미치는 영향

The Effect of Foliage Clipping on the Growth and the Agronomic Characteristics, as Affected by its Time, Degree, and Nitrogen Top-Dressing, in Rice plants

수도품종 "진흥" 공시하여 경엽의 절제 시기 및 정도, 그리고 절제 후의 시비량의 차이가 생육 및 수량형질에 미치는 영향을 알고저 보통기재배조건하에서 최고 분얼기와 그 10일 전후에 무절제구 및 초장의 1/3, 1/2, 2/3절제구에 질소를 10a당 0, 2, 4, 6kg 시용하는 시험을 실시한 바 그 결과는 다음과 같다. 1. 생육에 미치는 영향 : 경엽의 절제구는 절제 후 10 일간에 급속히 생장하며, 대체로 20일 후에는 거의 회복되었다. 1) 절제시기가 늦을수록 생육속도는 빠르며, 유수형성기 전에 절제한 것은 거의 회복되고 조건에 따라서는 무절제구보다 시장하나 유수형성기 이후에 절제한 것은 다소 초장이 작았다. 2) 절제의 정도가 클수록 급속한 신장을 하며, 절제의 정도가 경한 것은 초장이 오히려 증대되었으나 심히 절제한 경우에는 완전한 회복이 이루어지지 않았다. 3) 절제 후의 질소시용은 생육을 촉진하는 효과가 있었으며, 그 정도는 시비량이 많을수록 컸다. 4) 경엽의 절제는 출수를 지연시켰으며, 절제시기가 늦을수록, 절제정도가 클수록, 그리고 절제 후의 질소시용량이 많을수록 그 경향은 뚜렷하였고, 범위는 6일간이었다. 2. 수량형질에 미치는 영향 : 수량은 경엽의 절제에 의하여 대체로 감소되었으나 조건에 따라 변이가 커서, 대조구에 비해 최고 약 25%의 감수 및 10%의 증가를 보였다. 1) 유수형성기 이후의 절제는 간장, 수수, 1수정화수 및 등열율을 감소시키고, 수장 및 유효경비를 다소 증대시켰으며, 수량 및 고중은 약 10% 감소되었다. 2) 경엽의 절제가 경한 경우에는 유효경비가 다소 증대되었으나 1수정화수는 다소 감소되었고 수량 및 고중도 약 4~5% 감소되었다. 그러나 초장의 2/3를 절제하면 수장, 수수 및 1수정화수가 뚜렷이 감소되었고, 수량 및 고중도 약 10% 정도 감소되었다. 3) 절제 후의 질소시용은 10a당 2kg 이하일 경우에 유효하였으며, 4kg 이상의 시용은 간장, 수장, 1수정화수 및 고중을 다소 증대시켰으나 등열율 및 천엽중을 감소시키고 수량은 시용량의 증가에 따라 감소되었다. 따라 감소되었다.

To investigate the effects of foliage clipping time, degree, and nitrogen top-dressing after clipping on the growth and the agronomic characteristics, rice plants grown under ordinary cultural practices were clipped at the maximum tiller stage, 10 days prior to, and after that stage, respectively, with varying clipping, height, as 0, 1/3, 1/2, and 2/3 of plant height. And nitrogen was top-dressed at the rate of 0, 2, 4, 6 kg per 10 are immediately after clipping. The variety used was ＂Jinheung＂. The results obtained are outlined as follows: 1. Effect of clipping on the growth of rice plant: The subsequent growth was quite rapid during 10 days after clipping, and resulted, on the whole, in nearly complete recovery of defoliation by 20 days after clipping. a) Generally, the later the clipping time, the more growth accelerated. Rice plants clipped before the differentiation of ear primordia nearly recovered the damage, and in certain cases exceeded non-clipped plants in height. But the height of the rice plant clipped after the differentiation of ear primordia was somewhat smaller than that of non-clipped. b) Growth rate was rather rapid in the case of severe cutting, and the height of slightly clipped plants was taller than that of non-clipped plants. However, rice plants clipped to the extent of 2/3 of plant height did not fully recover the damage of defoliation compared to non-clipped plants. c) Nitrogen dressing was effective to rapid recovery of defoliation, the effect increasing with the increasing amount of application. d) Ear-heading was delayed in clipped plots, and this tendency was more apparent with later clipping time, more severe clipping, and increased amounts of nitrogen application after cutting. The range was 6 days at maximum. 2. Effect of defoliation on the yield and its components of rice plants: The yield response to clipping varied somewhat with its time, degree, and nitrogen application after cutting: yield increase of about 10% and decreasement of about 25% at maximum compared to the control plot. Grain yield of most plots was decreased. a) Clipping before the differentiation of ear primordia did not much affect the agronomic characteristics of rice plants. However, clipping after that growth stage decreased culm length, number of panicles, number of spikelets per panicle, and maturing rate of grain to some extent. Consequently this treatment resulted in decrease of about 10% in grain and straw production in spite of increase in panicle length and effective tillering rate. b) Slight, clipping decreased number of spikelets per panicle a little, and the yield of grain and straw by 4-5%, although effective tillering rate was somewhat increased. With severe clipping, panicle kngth, number of panicles, and number of spikelets per panicle decreased more, and the yield of grain and straw decreased about 10%. c) Nitrogen dressing after clipping at the rate of 2 kg per 10 are was effective in increasing grain yield. Nitrogen application over the rate of 4 kg per 10 are increased culm length, number of spikelets per panicle, and straw production, but this decreased the maturing rate, and the 1, 000-grains weight to some extent and resulted in decrease of grain yield.