Growth and development of soyabean cv. TK5 as affected by tropical daylengths, day/night temperatures and nitrogen nutrition

Abstract

S U M M A R YTwo experiments were done in Saxcil growth cabinets in order to investigate the effects of climatic factors and nitrogen nutrition on the growth, reproductive development and seed yield of soyabean cv. TKg. In the first, plants were grown to maturity in eight environments comprising all combinations of two short daylengths (I I h 40 min and 13 h 20 min), two day (27 and 33 "C) and two night (19 and 24 "C) temperatures. In the second, day temperature was kept at 33 "C but the night temperature was varied (19 and 24 "C) as was the mineral nitrogen supply (20 and 197 ppm N) to plants which were either inoculated or not with an effective single strain of Rhizobium.Taller, more branched, later flowering plants were produced in the longer daylength but seed yield was hardly affected because the components of yield did not all respond similarly. I n the higher day temperature treatments seed yield per plant was reduced by half because all yield components were adversely affectedpods per plant by 34 %, mean seed dry weight by 24 % and seeds per pod just slightly. There was a marked effect of the higher night temperature which promoted early vegetative growth, induced early flowering and although the number of pods per plant was, overall, reduced by 48 %, seed yield per plant was little affected as mean seed dry weight was increased by 37 yo and the number of seeds per pod was also increased slightly.Prior to flowering, nodulated plants obtained about two thirds of their total nitrogen requirement via direct uptake and one third through the symbiotic system. Vegetative dry weight and plant nitrogen content were increased by the higher mineral nitrogen level and, although height was slightly diminished, more branches were produced. Seed yield, however, was only slightly increased.These experiments have shown that night temperature is an environmental factor of major importance for the growth of this soyabean cultivar. They have provided, also, a more rational basis for interpreting seasonal variations in growth and seed yield of soyabean in the tropics where, clearly, day and night temperature effects can override those of daylength and nitrogen nutrition.

Response of Soybean Yield to Daytime Temperature Change during Seed Filling: A Long-Term Field Study in Northeast China

“…The results agree with the findings of the controlled environment studies that soybean seed yield increases as daily maximum temperature during seed development increases in cooler regions (Huxley et al, 1976;Sionit et al, 1987;Pan, 1996). At Hailun agroecosystem experiment station, the mean daily maximum temperature during seed fi lling varied from 20 to 24ºC over the study period which is within the maximum temperature range (18 to 30ºC) that gave maximum grain yield as found in the above studies.…”

“…In order to adapt soybean systems to the increased daytime temperature, a comprehensive understanding of the impact during seed filling on soybean yield is warranted. Controlled environment chambers have proven that moderate increase in daytime temperature (18−26ºC) during seed fi lling benefi ted soybean yield (Sionit et al, 1987), but soybean yield decreased as daytime temperature increased above 26ºC (Huxley et al, 1976;Dornbos and Mullen, 1991;Gibson and Mullen, 1996). In the controlled experiments, daytime temperatures were held constant during seed filling; in contrast, daily maximum temperature in the fi elds varies daily and gradually decreases during the period.…”

Growth of High-Yielding Soybeans and its Relation to Air Temperature in Xinjiang, China

“…On the contrary, Saitoh et al (1998) found that the number of pods was closely correlated with the total number of fl oral buds but not with pods set. A high night temperature reduces seed yield (Huxley et al, 1976;Sato and Ikeda, 1979;Seddigh and Jolliff, 1984). Therefore, further research is required to determine the effects of air temperature on fl oral bud differentiation and pod setting as a limiting factor of seed yield in Xinjiang.…”

“…On the other hand, pod number is considered to be one of the main factors for determining seed yield, and the variation in seed yield was often explained by pod number (Ikeda and Sato, 1990;Shimada et al, 1990;Board and Harvill, 1994;Wang et al, 1995;Saitoh et al, 1998). A high night air temperature has been reported to increase pod number (Gibson and Mullen, 1996;Zheng et al, 2002), but to reduce seed yield (Huxley et al, 1976;Sato and Ikeda, 1979;Seddigh and Jolliff, 1984). In this experiment, therefore, we examined the differences in growth among years in terms of the effect of air temperature on the growth parameters and pod setting, and to assume the conditions necessary to obtain a high yield in soybean in Xinjiang, China.…”

“…In 2005, however, the seed yield was very low. Such a fl uctuation in seed yield among years is infl uenced largely by climatic conditions, especially by air temperature (Hesketh et al, 1973;Huxley et al, 1976;Sato and Ikeda, 1979;Seddigh and Jolliff, 1984;Jiang and Egli, 1995;Gibson and Mullen, 1996;Uchikawa et al, 2003;Kitano et al, 2006). On the other hand, pod number is considered to be one of the main factors for determining seed yield, and the variation in seed yield was often explained by pod number (Ikeda and Sato, 1990;Shimada et al, 1990;Board and Harvill, 1994;Wang et al, 1995;Saitoh et al, 1998).…”