Influence of temperature and ultra-violet light on viability and infectivity of Peronospora tabacina sporangia

Blue mold of tobacco, caused by Peronospora tabacina, is a serious disease with severe commercial impact. Quarantine measures to reduce pathogen distribution affect commercial trade of tobacco even in processed stages, but survival of the pathogen after curing at high temperature or exposure to sunlight has not been investigated adequately. To assess the effect of heat and UV-light on viability and infectivity of P. tabacina, sporangia of two different strains and sporulating leaves were exposed to temperatures up to 70 °C and UV irradiation at 254 and 366 nm. Sporangial germination of both strains strongly decreased within 48 h at temperatures above 16 °C, but 1–3% of sporangia still survived 24 h treatment at 70 °C. When sporulating leaves were used to inoculate fresh tobacco, reinfection occurred with samples kept for 48 h at 50 °C, whereas no infection resulted when the inoculum had been stored at 70 °C for at least 24 h. Exposure to 254 nm UV-light was deleterious to sporangial germination and killed them within 30–40 min. In contrast, sporangia treated at 366 nm survived for more than 4 h. Similarly, sporulating leaves exposed to 254 nm were infective to fresh tobacco, when irradiation time remained below 40 min. The results suggest that thermal treatment of at least 70 °C in post-harvest processing is necessary to prevent infection risks from commercially used tobacco. Alternatively, short-term irradiation with 254 nm UV light could be used for quarantine management, if it does not affect the product quality.     

Display practices and changes in riboflavin content of non-fermenting palm juice

Changes in riboflavin content of industrially bottled palm juice stored at different light intensities similar to display patterns practised by traders was studied. The loss of riboflavin in the first 24 hours was significantly higher than in the second 24 hours in both transparent (P<0.001) and green bottles (P<0.02) exposed to bright sunlight. Riboflavin loss from samples stored in transparent bottles occurred at a faster rate (24–71% of initial) than from samples in green bottles (0–29%) over a 36-hour period. Further loss of riboflavin did not occur over the next 36 hours due to cool weather conditions. In contrast, only 6% of initial riboflavin was lost after 72 hours of continuous exposure to fluorescent light: this increased by 53% by the ninth week. The data showed that riboflavin loss from bottled palm juice varied with the container, the environmental conditions and period of storage. It is recommended that palm juice should be displayed in dark bottles and protected from bright light.     

Effects of sulphur dioxide and nitrogen dioxide on fourSolanum tuberosum L. cultivars

The effects of sulphur dioxide (SO₂) and nitrogen dioxide (NO₂), singly and in combination, on the shoot growth of four potato cultivars differing in maturity classification (Solanum tuberosum L. ‘Superior,’ ‘Norchip,’ ‘Kennebec, rs ‘Russet Burbank’) were determined in controlled conditions. Plants were exposed to 0.11 ppm SO₂ and/or 0.11 ppm NO₂ for 24 hours a day for 7 or 14 days. There were no significant differences in leaf growth of ‘Superior’ or ‘Norchip’ plants at 7 or 14 days. Stem dry weight was significantly reduced in ‘Superior’ only after 14 days in the mixture. ‘Kennebec’ and ‘Russet Burbank’ plants had significantly less leaf area, leaf fresh weight, and leaf water content after 14 days of exposure to the mixture, but there was no significant change in dry weight. Specific leaf weight was significantly increased in the mixture treated plants of both cultivars. The two earlier maturing cultivars, ‘Superior’ and ‘Norchip,’ were less sensitive to the SO₂ and NO₂ combination than the two later maturing cultivars, ‘Kennebec’ and ‘Russet Burbank’.     

Effect of temperature on the developmental time,survival of immatures and adult longevity of Aganaspis daci (Hymenoptera: Figitidae), a natural enemy of Ceratitis capitata (Diptera: Tephritidae)

Longevity, developmental time and offspring survival of parasitoid wasps are decisive in their effective performance as biocontrol agents. Optimum temperature range determines parasitoid survival, development and reproduction. Thus, controlling this abiotic factor is a key to the success of pest management programs. Adult longevity, developmental time from egg to adult and survival of immatures of Aganaspis daci were assessed in the laboratory under different constant temperatures; adult longevity without hosts, but with the provision of water and honey, and developmental time and survival of immatures from host pupae, whose larvae had been exposed to parasitoids. Results showed that longevity depended on temperature decreasing in the range 15–20 °C (36 – 25 days), but was lower in the range 25–35 °C (10 – 7 days). Regarding developmental time from egg to adult and survival of immatures, our results showed that 20 and 25 °C are the most suitable temperatures. At 15 and 30 °C mortality of the immature stages was very high (>90%) or developmental time to adult was very slow (>3 months). Immatures did not survive at 35 °C. We found no significant differences in developmental time to adult or survival of immatures between 20 and 25 °C. The sex ratio of parasitoid progeny was female biased at 25 °C; the proportion of females increased at all cases with temperature. The t_o and K for total development were 8.5 °C and 500 DD, respectively. Our findings provide some guidance for future inundative or inoculative field releases of this parasitoid for the management of Ceratitis capitata in Spain.     

Internodal elongation: A potential screening technique for heat tolerance in potato

Summary In pot culture experiments over 2 consecutive years, 20 potato genotypes of varying heat tolerance were grown under long day conditions and heat stressed by being exposed to high (38 °C/21 °C mean day/night) temperature. The percent increase in mean internode length of heat stressed plants over those grown at normal temperatue (25°C/16°C day/night) was correlated with the percent tuber dry matter yield of the heat stressed plants (r=0.618, P=0.01). In the same 20 genotypes, grown under short day conditions at normal temperature, the fraction of leaf bud cuttings exposed to high night temperature (23°C) that produced tuber initials correlated with the percentage increase in internode elongation in stem cuttings exposed to 25°C compared with those exposed to 15°C (r=0.680. P=0.01). Thus the relative changes in internode elongation are related to thermal tolerance, and it is suggested that this can be used as a selection criterion for heat tolerance.     

Insecticide-induced changes in the levels of resistance of rice cultivars to the whitebacked planthopper Sogatella furcifera (Horváth) (Homoptera: Delphacidae)

IR2035-117-3 (highly resistant), ARC 10239 (resistant), and TN1 (susceptible) rice plants received one application at 40 days after transplanting (DT) or three spray applications (20, 30, and 40DT) of monocrotophos, diazinon or deltamethrin. When these plants were exposed to S. furcifera adults, either 24 hours after the single application, or 15 days after the third of the spray applications, the deltamethrin-treated were most preferred. The percentage of S. furcifera that alighted on the three varieties decreased correspondingly with an increase in the level of varietal resistance. Differences in S. furcifera population growth, nymphal survival, nymphal duration, growth index and feeding rate between IR2035-117-3 and TN1 were significant. Foliar application of deltamethrin caused a significant increase in population growth on IR2035-117-3, ARC 10239, and TN1 and an increase in the nymphal survival and growth index on TN1.     

Genetic variability and interrelationship among various morphological and quality traits in quinoa (Chenopodium quinoa Willd.)

Evaluation of seed yield, morphological variability and nutritional quality of 27 germplasm lines of Chenopodium quinoa and 2 lines of C. berlandieri subsp. nuttalliae was carried out in subtropical North Indian conditions over a 2-year period. Seed yield ranged from 0.32 to 9.83 t/ha, higher yields being shown by four Chilean, two US, one Argentinian and one Bolivian line. Two lines of C. berlandieri subsp. nuttalliae exhibited high values for most of the morphological traits but were low yielding. Seed protein among various lines ranged from 12.55 to 21.02% with an average of 16.22 ± 0.47%. Seed carotenoid was in the range of 1.69–5.52 mg/kg, while leaf carotenoid was much higher and ranged from 230.23 to 669.57 mg/kg. Genetic gain as percent of mean was highest for dry weight/plant, followed by seed yield and inflorescence length. All morphological traits except days to flowering, days to maturity and inflorescence length exhibited significant positive association with seed yield. The association of leaf carotenoid with total chlorophyll and seed carotenoid was positive and highly significant. The path analysis revealed that 1000 seed weight had highest positive direct relationship with seed yield (1.057), followed by total chlorophyll (0.559) and branches/plant (0.520). Traits showing high negative direct effect on seed yield were leaf carotenoid (−0.749), seed size (−0.678) and days to flowering (−0.377). Total chlorophyll exerted strongest direct positive effect (0.722) on harvest index, followed by seed yield (0.505) and seed protein (0.245).     

Sublethal and transgenerational effects of chlorantraniliprole on biological traits of the diamondback moth,Plutella xylostella L.

The diamondback moth, Plutella xylostella (L.), is an important international pest of cruciferous vegetables. The effects of the new diamide insecticide chlorantraniliprole, at a lethal concentration inducing only 25% mortality (LC₂₅), were assessed on the development and reproductive parameters of P. xylostella under laboratory conditions. In addition, effects on development time, pupation rate, larval and pupae weight, fertility, and survival in the parent and F1 generations were assessed. When 4th instar P. xylostella larvae were exposed to LC₂₅ of chlorantraniliprole on a cabbage (Brassica oleracea var. capitata L.) leaf for 96 h, we observed increased developmental time for 4th instar larval to pupa period (4.27 days vs. 3.34 days in the control), lower pupal weight (3.58 mg vs. 4.17 mg in the control) and decreased adult fecundity (by 42%). F1 generation underwent transgenerational effects, i.e. higher developmental time from egg to pre-pupae and lower egg hatching rate occurred. Demographic growth parameters, such as the net reproductive rate (R₀), the intrinsic rate of increase (r_m), and finite rate of increase (λ) were significantly lower for the LC₂₅ chlorantraniliprole treated group than for the untreated control. Our results suggest that exposure to LC₂₅ of chlorantraniliprole may have negative effects both on exposed individuals and on subsequent generations in P. xylostella.     

Electrotherapy and shoot tip culture eliminate potato virus X in potatoes

Potato stems infected with potato virus X (PVX) were exposed to either 5, 10, or 15 miliampers (mA), for 5 or 10 minutes, followed by immediate planting the axillary buds tipin vitro. Temperature increased from 4 to 10 C in the tissues during the exposure to the electricity. After a 60 days growing period, therapy efficiency (TE, TE = % plant regeneration X% virusfree resulting plants) was influenced by the severity of treatment, since organogenesis and virus elimination were both stimulated by the electricity. The highest TE values were obtained at 15 mA for 5 minutes. Under these conditions, 40% to 80% of the buds regenerated, and 60% to 100% of the regenerated plantlets tested virus negative.     

Shade reduces growth and seed production of Echinochloa colona,Echinochloa crus-galli,and Echinochloa glabrescens

Echinochloa species are problematic weed species in direct-seeded rice systems in Asia. Because of concern about the continuous use of single herbicides, cultural weed management strategies need to be developed to maintain the sustainability of direct-seeded rice systems. However, the design of such strategies requires an understanding of the differential responses of weeds to shade caused by crop interference. The effects of shade on growth and seed production of Echinochloa colona, Echinochloa crus-galli, and Echinochloa glabrescens were determined. Weeds of three Echinochloa species were grown continuously in full sunlight or in 50% or 25% of full sunlight, or started in full sunlight and transferred to 50% or 25% of full sunlight at 21 days after sowing. The results suggested that changes in shade regime did not affect the plant height of E. colona and E. glabrescens; however, shade reduced the height of E. crus-galli. Compared with the plants grown in full sunlight, 75% of continuous shade reduced E. crus-galli height by 22%. Shade reduced leaf, total shoot, and root biomass and seed production in all the weed species, if occurred during the early growth of the weeds. The weeds responded with increased leaf biomass ratio when grown in shade. Compared with full sunlight, continuous shade of 75% increased leaf biomass ratio by 90% in E. colona and this value was 25% in the other two species. The results of this study show that shade can reduce weed growth and seed production of Echinochloa species but it should not be considered as a stand-alone strategy to manage these weeds in rice. This highlights the need for the integration of other weed management strategies to achieve complete control of these species.     

Impacts of weather,shade cover and elevation on coffee leafminer Leucoptera coffeella (Lepidoptera: Lyonetiidae) population dynamics and natural enemies

We assessed the influences of ambient temperature, rainfall, shade cover and elevation on seasonal abundance of coffee leafminer Leucoptera coffeella (Guérin-Ménèville) and its natural enemies in coffee farms in the Soconusco region of Chiapas, Mexico. Mined coffee leaves were most abundant during the rainy season (i.e. historical average rainfall >200 mm/mo, April–November) compared to the dry season (<100 mm/mo, December–March), and at low (<600 m asl) relative to high (>900 m asl) elevations. The abundance of mined leaves increased with rainfall, and decreased with maximum daily temperatures. Coffee leafminer survivorship was highest during the dry season (>40%), when predation was lowest (<10%). Predation was the main source of coffee leafminer mortality, and was greatest during the rainy season (>25%) when coffee leafminer incidence was highest (>30% mined leaves per plant). None of the weather variables that were evaluated (viz. maximum and minimum temperatures, and rainfall) significantly impacted parasitism ratios. Shade cover moderated on-farm temperatures, by reducing maximum daily temperatures and any potential, direct impacts of rainfall on coffee leafminer, by providing partial shelter from rainfall, but did not significantly affect coffee leafminer incidence. In 48 h laboratory trials, coffee leafminer oviposition was highest at 28 °C (∼15 eggs/female), minimal at 25 °C (∼3 eggs) and nil at 20 °C, and higher during night-time hours (>8 eggs/female/day) compared to day-time hours (<1 egg). Historical average temperatures were higher at low elevation (yearly average ca. 25 °C; range = 18.0–32.0 °C) than at high elevation (ca. 21 °C; 13.5–28.5 °C), and we predicted that physical environmental conditions (i.e. night-time hours with temperatures > 20 °C) were permissive of coffee leafminer oviposition during twice as many hours each year at low elevation (4060 h) compared to high elevation (2081 h). Overall, our results suggested that evident differences in the abundance of coffee leafminer between elevations may be due in considerable part to differences in ambient temperatures, particularly night-time temperatures, rather than rainfall, shade cover, or elevation per se.     

Responses of sunflower yield and grain quality to alternating day/night high temperature regimes during grain filling: Effects of timing,duration and intensity of exposure to stress

In order to quantify the effects, at different stages during grain filling, of alternating day/night high temperature regimes on sunflower grain yield and quality, heads were exposed to high temperatures during 7 or 6 days starting either 10–12 days after anthesis (daa, HT1), 18 daa (HT2) or 24 daa (HT3). Also, heads were exposed to high temperatures for periods of 2, 4 or 6 days in each of HT1 and HT2. Temperatures covered a range of mean daily grain temperature of 20–40 °C and peak grain temperatures (i.e., those prevailing during the central 5 h of the daylight period) of 26–45 °C. High temperature stress for periods of 4 days or longer produced significant (p < 0.05) reductions in grain yield and grain quality. Early (HT1) exposure to stress reduced yield by 6%/°C above a mean grain temperature threshold of 29 °C; later (HT2 + HT3) exposures reduced yield by 4%/°C above a threshold of 33 °C. These reductions in yield were attributable to reductions in unit grain weight at all positions (periphery, intermediate, central) on the head, and an increase in the proportion of very small (10–30 mg) grains, termed half-full (HF) grains in this paper. In both full and HF grains, stress in either HT1 or HT2 reduced final pericarp weight, associated with fewer number of cell layers and thinner cell walls in the schlerenchyma. High temperatures reduced both the rate and duration of oil deposition in the grain, with the greatest effects being found with early (HT1) exposures. The unsaturation (oleic acid/linoleic acid) ratio of oil from mature grain was altered only when exposure to heat stress overlapped with the cessation of deposition of storage lipids. The effects of duration and intensity of heat stress on relative (to control) grain yield and oil content could be reasonably summarized using a linear response to cumulative hourly heat load calculated with a base temperature of 30 °C. We conclude that: (i) 4 days of alternating day/night temperatures resulting in mean daily grain temperatures of >30 °C can reduce sunflower grain yield and quality; (ii) the magnitude of these effects is strongly dependent on the timing of exposure and their nature on the grain growth processes active at the time of stress; and (iii) an hourly heat load (base = 30 °C) provides a useful integrative estimator of the effects of exposure to heat stress on grain yield and oil content for a given phase of grain filling.     

Response of ten potato cultivars to temperature as measured by chlorophyll fluorescencein vivo

Forty-day-old plants of ten cultivars of potato,Solanum tuberosum L. (Alpha, Atlantic, Bintje, Caribe, Kennebec, Red Pontiac, Russet Burbank, Sebago, Shepody and Superior), were placed into a controlled environment chamber held continuously at 35 C and their growth (Plastochron Index) and several chlorophyll fluorescence parameters (O, P, T, Fv and Fr) were measured after 1, 14, 21 and 28 days’ exposure. The cultivars were grouped according to heat tolerance based upon survival of three of four plants. The least heat tolerant group, surviving 14 days, included Atlantic, Bintje and Superior. The medium heat tolerant group, surviving 21 days’ exposure, included Kennebec, Red Pontiac and Sebago. The best heat tolerant group, surviving 28 days’ exposure, included Alpha, Caribe, Russet Burbank and Shepody. In addition, chlorophyll fluorescence parameters of six plants of each cultivar were also measured after 1 h at 5, 15, 25 and 35 C exposure in a second experiment. In all cases plants in the group with the least tolerance displayed less fluorescence than the medium or high heat tolerance plants, suggesting that plants with the least tolerance to high temperature exposure had less energy transfer through PSII (Photosystem II). These plants also had a rise in T at temperatures aboveca. 15 C. A decrease in Fv during growth at 35 C was a good indicator of foliar heat damage. Chlorophyll fluorescence of plant tissue in all three groups increased after short exposure of 1 h to temperatures below 15 C and also after continuous exposure to 35 C. At both ranges of temperature, damage was probably occurring to the thylakoid membranes which inhibited re-oxidation of PSII. Since the rate of response was different, chilling and high temperature apparently differ in how they alter the thylakoid membranes.     

大豆种子抗老化鉴定的方法研究

选用遗传差异相对较大的皖豆24、皖豆25(杂交品种)及合豆3号的种子,在温度为40℃、湿度为85%的条件下老化处理4、8和12 d,研究加速老化过程中不同基因型大豆种子成苗率、发芽率、电导率及单株幼苗干重的变化规律。结果表明:随着加速老化时间的延长种子活力下降;加速老化处理8 d,3个品种的各项鉴定指标均发生改变:品种的成苗率、发芽率及单株幼苗干重显著降低,电导率明显升高,且品种间有显著差异;发芽率和成苗率的变化在品种间具有一致性,电导率、单株幼苗干重的变化和成苗率品种间一致性较差;成苗率和发芽率的相关性最高(r=0.972**)。利用国家大豆微核心种质中的91份资源对老化鉴定方法进行验证,结果在温度为40℃,湿度为85%条件下老化8 d的种子发芽率及老化指数与在自然条件下老化15个月的发芽率及老化指数极显著相关(r=0.943**,0.716**)。综合分析认为,温度为40℃,湿度为85%条件下老化处理8 d,以种子发芽率为活力鉴定指标可作为大豆种子抗老化性的鉴定方法。     

丹东杂草稻种子的耐冻能力和低温发芽特性研究

为了解丹东杂草稻种子冬季在野外能存活的原因,将丹东杂草稻和对照品种越光的干种子在水中浸不同时间,后在-20℃下处理7 d,在25℃下发芽。对照品种越光在浸种1 h后冷冻处理,其种子的发芽率从98％降为4％,浸种时间延长到1.5 h已不能成苗,而丹东杂草稻种子在1 h浸种处理后,其发芽基本不受影响,甚至在3 h浸种处理后成苗率仍达2.3％。在不同低温下发芽试验中发现丹东杂草稻在11℃能发芽,杂草稻的发芽临界温度要比对照越光低。讨论了杂草稻种子抗冻的潜在价值。      

秋季低温对水稻空瘪率的影响和有关指标值的研究

本试验旨在探索秋季低温对水稻开花结实影响的若干不够明确的问题。结果表明:低温指标中,日平均温度是主要指标;日最低温度是减数分裂期的辅助指标;日最高温度是开花期的辅助指标。如在不同低温敏感期均受害较重,则低温危害表现为累加效应。计算低温临界温度时,籼粳稻均以连续三天的温度平均为好。提出了开花期籼稻、籼型杂交稻、中粳、晚粳四类型的低温临界值。开花期的日温差过大或过小均导致空瘪率上升。气象因子中,温度对空瘪率的影响最大;适温条件下,空瘪率与日照呈负相关:雨量与空瘪率关系不显著。     

Floret development and spike growth as affected by photoperiod during stem elongation in wheat

A longer duration of stem elongation (from terminal spikelet initiation to anthesis) would result in a higher wheat yield potential as a consequence of the increase in both spike dry weight and number of fertile florets at anthesis. It is not clearly understood, however, which processes are involved in the increased spike dry weight and whether this variable accounts for the higher number of fertile florets when duration of stem elongation is modified by photoperiod treatments. As vernalization interacts with photoperiod during the stem elongation phase, a better understanding of the role of vernalization is also required. A field experiment was carried out using two wheat cultivars (Buck Manantial (BM) and Eureka Ferrocarril Sur (EFS)) subjected to diverse periods of vernalization (V₁₅ and V₅₀, plants vernalized for 15 and 50 days, respectively) and exposed to different photoperiods (NP+0 and NP+6, natural and 6 h extended photoperiod, respectively) only during the stem elongation phase. Floret development together with stem and spike growth during the stem elongation phase were studied. When the stem elongation phase was exposed to short photoperiod (i) duration of spike growth increased without any change in its growth rate, and (ii) most of the spike growth occurred during minimum stem growth rate as the onset of maximum stem growth rate was delayed. In EFS, the vernalization-sensitive cultivar, the former (i) and (ii) was true only when vernalization requirements were met. For both cultivars, the survival of the initiated floret primordia under short photoperiod increased, independently of vernalization. Both partitioning of assimilates to the spike and a direct photoperiod effect seemed to have been involved in the survival of floret primordia when the stem elongation phase was exposed to short photoperiod.     

Effect of short- and long-term exposure of seed tubers to low temperatures on the growth and yield of five potato cultivars

Trials were conducted in Alberta with Norchip, Norland, and Russet Burbank and in Ontario with Kennebec, Russet Burbank, Norchip, and Superior tubers to determine their response to short-term exposure to air temperatures of 0, ?1, and ?5 C and to long-term exposure to ?1, 0, 1,2, and 3 C. Exposure of seed tubers to ?1 C from 6 hours to 5 days did not affect growth characteristics or tuber yield of any of the five cultivars studied. Long-term (October–May) exposure to ?1 C in one study severely reduced emergence and tuber yield of Norchip (P<0.05). While the marketable yield of Russet Burbank was also reduced (P<0.05) by this treatment, Norland was not affected. Tubers of all cultivars exposed to air temperatures of ?3 or ?5 C for longer than 24 hours were severely injured and were not planted in the field trials at either location. In Alberta exposure of seed tubers of Norchip, Norland, and Russet Burbank to ?5 C for 6 and 12 hours caused a reduction (not significant) in yield. In Ontario, long-term storage at 1, 2, and 3 C and in combination with short-term (2 weeks) exposure to 0 or 10 C had no effect on growth or marketable yield of Norchip, Russet Burbank, Superior, and Kennebec seed tubers.     

Laboratory experiments of vacuum treatment in combination with an O2 absorber for the suppression of Sitophilus granarius infestations in stored grain samples

The effectiveness of vacuum (V) treatment alone and in combination with an oxygen absorber (V + A) for suppression of grain infestation by Sitophilus granarius L. were compared under laboratory conditions. The effectiveness of the treatment methods was evaluated at different temperatures (15, 25 °C) and exposure times (7, 14, 21, 28 days). We evaluated both the effects on adults present in grain interspaces and hidden infestations within the kernels in terms of treatment time separately. Adults of S. granarius present in grain interspaces were more susceptible to both treatments than hidden infestations developing within kernels. At 25 °C, total mortality of adults in grain interspaces was achieved after 10 days of exposure whereas total suppression of hidden infestations was achieved after 3 weeks. Higher temperature and longer exposure correlated with a greater effectiveness of the tested treatments. The addition of an oxygen absorber to the vacuum treatment (V + A) showed the general tendency of improving the effectiveness of the vacuum treatment on suppression of hidden infestations; significant differences between the V + A and V treatments were prominent primarily at the lower temperature tested. Reduction of hidden infestation was achieved after 3 weeks of exposure to V + A treatment (99.8%) and after 4 weeks of V treatment (95.8%) at 15 °C.     

Effects of Temperature on Growth and Dry Matter Accumulation in Mulberry Saplings

abstract

Prediction of mulberry (Moms alba L. cv. Shinn-ichinose) growth is necessary to cope with recent trends in mulberry cultivation. To develop a mulberry growth model, I investigated the response of mulberry growth to temperature. Mulberry saplings were grown in 1995 and 1996 at four constant (20, 24, 28, 32°C) and one diurnally fluctuating (32/24°C -mean 28°C) temperature conditions for 50-60 days in phytotrons under natural sunlight. Shoot length and leaf number were measured every 10 days during the temperature treatment and the dry matter of each plant part was measured at the end of the treatment period. Shoot length and leaf number increased exponentially with time at all temperatures examined, and these values increased with the increase in temperature. Shoot dry weight, over the period of the treatment, increased with temperature but the dry weights of stump and root were not affected by temperature. The optimum temperature for mulberry growth and dry matter accumulation was approximately 32°C.