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11.
In Argentina, delayed sowing causes a decrease in seed yield and in radiation use efficiency (RUE) of peanut crops (Arachis hypogaea L.), but it is not known if RUE reduction is mainly due to reduced temperature during late reproductive stages or to a sink limitation promoted by decreased seed number in these conditions. We analyzed seed yield determination and RUE dynamics of two cultivars (Florman and ASEM) in four irrigated field experiments (Expn) grown at three sites and five contrasting sowing dates (between 17 October and 21 December) in three growing seasons. An additional field experiment was performed with widely spaced plants (i.e. with no interference among them) to evaluate the effect of peg removal on RUE and leaf carbon exchange rate (CER). Seasonal dynamics of mean air temperature and irradiance, biomass production (total and pods), and intercepted photosynthetically active radiation (IPAR) were followed. Seed yield and seed yield components (pod number, seeds per pod, seed number and seed weight) were determined at final harvest. Crop growth rate (CGR) and pod growth rate (PGR) were computed for growth phases of interest. RUE values for crops sown until 14 November were 1.89–1.98 g MJ−1 IPAR, within the usual range. RUE decreased significantly for cv. Florman in the late sowing of Exp1 (29 November) and for both cultivars in Exp3 (21 December sowing). Across experiments, seed yield (4.5-fold variation relative to minimum) was strongly associated (r2 = 0.87, P < 0.0001) with variations in seed number (3.5-fold variation relative to minimum), and to a lesser extent (r2 ≤ 0.54, P ≤ 0.001) to variations in seed weight (1.9-fold variation relative to minimum). Seed number was positively related (P < 0.01) to CGR (r2 = 0.66) and to PGR (r2 = 0.72) during the R3–R6.5 phase (seed number determination window), while crop growth during the grain-filling phase (i.e. between R6.5 and final harvest) was positively associated with grain number (r2 = 0.80, P < 0.001). No association was found between RUE and mean air temperature, neither for the whole cycle nor for the phase between R6.5 and final harvest, which showed the largest temperature variation (16.4–22.4 °C) across experiments. Use of mean minimum temperature records (range between 13.8 and 18.5 °C) did no improve the relationship. However, grain-filling phase RUE showed a positive (r2 = 0.69, P = 0.003) linear response to seed number across experiments. This apparent sink limitation of source activity was consistent with the reduced RUE (from 2.73 to 1.42 g MJ−1 IPAR) and reduced leaf CER at high irradiance (from ca. 30 to 15 μmol m−2 s−1) for plants subjected to 75% peg removal. 相似文献
12.
Effects of partial root-zone drying on yield,tuber size and water use efficiency in potato under field conditions 总被引：1，自引：0，他引：1
Ali Shahnazari Fulai Liu Mathias N. Andersen Sven-Erik Jacobsen Christian R. Jensen 《Field Crops Research》2007
Water resources are limited for irrigation worldwide; therefore, there is a need for water-saving irrigation practices to be explored. Partial root-zone drying (PRD) is a new water-saving irrigation strategy being tested in many crop species. Experiments were conducted in potato (Solanum tuberosum L. cv. Folva) under open field conditions in 2004 and under a mobile rainout shelter in 2005. Two subsurface irrigation treatments were studied: full irrigation (FI) receiving 100% of evaporative demands, 50.1 and 201 mm of irrigation water in the 2 years, to keep it close to field capacity; and PRD, which received 21.7 and 140 mm of irrigation in 2004 and 2005 respectively. Due to rain in 2004, the PRD treatment was imposed over a short period only during the late tuber filling and maturing stages. In 2005, the PRD treatment was imposed during the whole period of tuber filling and tuber maturation. The PRD treatment was shifted from one side to the other side of potato plants every 5–10 days. Especially in 2005 it was apparent that stomatal conductance was generally lower in the PRD than in the FI plants, whereas leaf water potential tended to be lower in only a few instances. During the treatment period, plants were harvested five times, and no significant difference was found between the treatments in leaf area index, top dry mass and tuber yield. At final harvest, tubers were graded based on size into four classes C1–C4, of which the yield of the important marketable class (C2) was significantly higher (20%) in the PRD than in the FI treatment. Compared with FI, the PRD treatment saved 30% of irrigation water while maintaining tuber yield, leading to a 61% increase of irrigation water use efficiency. The limited data of 2004 support these results. In summary, PRD is a promising water-saving irrigation strategy for potato production in areas with limited water resources. 相似文献
13.
Zinc (Zn) pollution of croplands can have negative impacts on yields through its effects on key physiological functions such as transpiration rate (TR). Previous long-term experiments indicated that differential tolerance among soybean genotypes following exposure to high Zn levels existed in the shoots. There are, however, no studies of the possibility that short-term responses to Zn directly limit shoot TR. Measurements of TR of eight soybean genotypes were measured over 220 minutes after placing de-rooted shoots in 500 μM Zn solution. Six genotypes exhibited TR that decreased slowly in a linear fashion over time while two genotypes (‘PI 416937’ and ‘N01-11136’) exhibited very rapid decrease in TR following a Boltzmann sigmoid response. One possibility to explain these results is that there exists a Zn-sensitive AQP population in the leaves of ‘PI 416937’ and ‘N01-11136’ with abundance or activity that is much higher than in the leaves of the remaining six lines. 相似文献
14.
Eyüp Selim Köksal Süleyman Kodal Yusuf Ersoy Yildirim 《Agricultural Water Management》2010,98(2):353-360
Determination of temporal and spatial distribution of water use (WU) within agricultural land is critical for irrigation management and could be achieved by remotely sensed data. The aim of this study was to estimate WU of dwarf green beans under excessive and limited irrigation water application conditions through indicators based on remotely sensed data. For this purpose, field experiments were conducted comprising of six different irrigation water levels. Soil water content, climatic parameters, canopy temperature and spectral reflectance were all monitored. Reference evapotranspiration (ET0), crop coefficient Kc and potential crop evapotraspiration (ETc) were calculated by means of methods described in FAO-56. In addition, WU values were determined by using soil water balance residual and various indexes were calculated. Water use fraction (WUF), which represents both excessive and limited irrigation applications, was defined through WU, ET0 and Kc. Based on the relationships between WUF and remotely sensed indexes, WU of each irrigation treatments were then estimated. According to comparisons between estimated and measured WU, in general crop water stress index (CWSI) can be offered for monitoring of irrigated land. At the same time, under water stress, correlation between measured WU and estimated WU based on CWSI was the highest too. However, canopy-air temperature difference (Tc − Ta) is more reliable than others for excessive water use conditions. Where there is no data related to canopy temperature, some of spectral vegetation indexes could be preferable in the estimation of WU. 相似文献
15.
水汽压差(VPD)表征了大气水分亏缺的程度。为探讨番茄对高VPD的适应机制,并筛选出适宜高VPD环境条件下栽培的番茄品种,试验以6个番茄品种为材料,利用人工气候室,设置2个VPD处理:昼1.48 kPa/夜0.47 kPa(低VPD处理)和昼2.55 kPa/夜0.47 kPa(高VPD处理),研究不同VPD处理下番茄气孔特征、气体交换参数和生长的响应变化。结果表明:与低VPD处理相比,在高VPD处理下,‘中杂9号’、‘中杂105’的总干质量以及‘番茄06-2’和‘合作903’的壮苗指数显著降低,‘东亚粉冠’和‘金棚朝冠’的总干质量和壮苗指数变化不显著。高VPD处理下,‘中杂9号’‘中杂105’‘合作903’的光合速率和气孔导度显著的下降,而蒸腾速率变化不显著;相反,‘东亚粉冠’和‘金棚朝冠’的蒸腾速率显著升高,而光合速率和气孔导度变化不明显;6个番茄品种水分利用效率降低均达显著水平。此外,高VPD处理下6个番茄品种的气孔密度、指数、长度、宽度和开度均有不同程度的下降。相关性分析表明,气孔特征与气孔导度、光合速率和生长指标间呈正相关关系,而与气孔限制值呈负相关关系。最后,通过综合评价认为‘金鹏朝冠’和‘东亚粉冠’为适宜高VPD环境条件下栽培的品种。总之,气孔在植株对高VPD的响应中发挥了重要作用,是导致不同番茄品种对高VPD响应差异的关键。 相似文献
16.
《Plant Production Science》2013,16(2):184-191
AbstractIn the afternoon when air humidity decreases, leaf photosynthetic rate (Pn) often declines in rice grown under irrigated conditions. To clarify the genotypic difference of Pn in response to humidity, we measured Pn and stomatal conductance (gs) for nine rice varieties with diverse genetic backgrounds, at various vapor pressure differences (VPD) and developmental stages. Pn and gs of all the varieties decreased with VPD increase from 1.0 to 2.3 kPa of VPD. The variety with high gs at low VPD exhibited a greater decline of gs with VPD increase than the variety with low gs, but cv. Takanari showed the highest gs under altered VPD conditions. Significant logarithmic relations were found between the decreased Pn and gs at the respective developmental stages, suggesting that gs is the dominant factor determining Pn and its response to VPD change. To explicate the effect of decreased gs on Pn, we analyzed the relations by using the model that accurately estimated the genotypic difference in Pn at a low VPD with gs and leaf nitrogen content per unit leaf area in the previous study. The model assuming that leaf internal conductance (gw) remains unchanged well explained the decreased Pn at high VPDs by gs change alone. The analysis also suggested the constancy of gw and carboxylation capacity at high VPD. It is concluded that the genotypic difference in the decrease of Pn at a high VPD is brought mainly by that in decreased gs, and the varieties with a high gs always exhibit a high Pn owing to their relatively high gs at either high or low VPD environments. 相似文献
17.
7种番荔枝果树的叶片结构及其与抗寒性关系研究 总被引：18，自引：0，他引：18
应用叶片离析法和石蜡制片技术,对番荔枝科番荔枝属6种果树和比丽巴属1种果树的叶表皮特征和叶结构特征进行了研究。结果表明,番荔枝属的刺果番荔枝、山刺番荔枝和圆滑番荔枝表皮细胞垂周壁呈波浪状,表皮毛短或无;叶片厚度大,叶脉突起度(叶脉厚度/叶片厚度)小。杂交种番荔枝、非洲骄傲番荔枝(品种)、牛心番荔枝、秘鲁番荔枝以及比丽巴属的比丽巴番荔枝表皮细胞垂周壁呈直或弧状,表皮毛长;叶片厚度小,叶脉突起度大。还讨论了番荔枝果树叶片解剖特征与果树抗寒性的关系,认为表皮毛长、叶脉突起度大是抗寒性强的性状,反之则是抗寒性弱的表现。 相似文献
18.
Arumugam Thiagarajan Rajasekaran Lada Steeve Pepin Charles Forney Yves Desjardins Martine Dorais 《Scandinavian Journal of Forest Research》2016,31(1):1-7
Low temperature (LT) exposure has been shown to delay postharvest needle abscission and senescence (NAS) in balsam fir and changes in vapor pressure deficit (VPD) are expected to alter these processes. Two and half year-old seedlings were exposed to a LT of 5°C for 15 days while the control (CT) group was maintained at 22°C. Seedlings were then exposed to four different VPD (0.22, 0.87, 1.3 and 1.86?kPa) and observed for relative water content (RWC), xylem pressure potential (XPP), membrane injury index (MII), stem capacitance (SC) and NAS. An interactive effect of LT and VPD was observed in RWC, XPP, MII and NAS. Low VPD (0.22 and 0.87?kPa) resulted in less negative XPP, lower electrolyte leakage, higher SC and ultimately higher NAS than those at high VPD. Maximum NAS was recorded at 0.22?kPa. At 1.86?kPa, LT had 5× lower RWC (13%), 3× more negative XPP (?1.1?MPa), 1.8× higher membrane damage and 35% lower NAS (47 days) than CT. The SC declined with an increase in VPD with no effect of LT. The XPP and RWC of LT seedlings showed a positive relationship with NAS with R2 values of 0.54 and 0.59, respectively. LT offered no benefits to NAS at high VPD environments. 相似文献