BackgroundPollen tube elongation in the pistil is a key step for pollination success in plants, and auxins play an important role in this process. However, the function of auxins in pollen tube elongation in the pistil of rice under heat stress has seldom been previously reported.ResultsTwo rice genotypes differing in heat tolerance were subjected to heat stress of 40 °C for 2 h after flowering. A sharp decrease in spikelet fertility was found in the Nipponbare (NPB) and its mutant High temperature susceptible (HTS) under heat stress, but the stress-induced spikelet sterility was reversed by 1-naphthaleneacetic acid (NAA), especially the HTS. Under heat stress, the pollen tubes of NPB were visible in ovule, while those of HTS were invisible. However, we found the pollen tubes in ovule when sprayed with NAA. During this process, a significant increase in indole-3-acetic acid (IAA) and reactive oxygen species (ROS) levels was found in the pistil of heat-stressed NPB, while in heat-stressed HTS they were obviously decreased. Additionally, the peroxidase (POD) activity in pistil of NPB was significantly decreased by heat stress, whereas there was no difference between the heat-stressed and non-heat-stressed pistils of HTS.ConclusionIt was concluded that the enhancement of heat tolerance in plants by NAA was achieved through the increase of the levels of auxins, which prevented the inhibition of pollen tube elongation in pistil, and the crosstalk between auxins and ROS, which might be involved in this process. In addition, POD might be a negative mediator in pollen tube elongation under heat stress due to its ability to scavenge ROS and degrade auxin.Electronic supplementary materialThe online version of this article (10.1186/s12284-018-0206-5) contains supplementary material, which is available to authorized users.

Water samples have been collected from a part of Surma River along different points and analyzed for various water quality parameters during dry and monsoon periods. Effects of industrial wastes, municipal sewage, and agricultural runoff on river water quality have been investigated. The study was conducted within the Chattak to Sunamganj portion of Surma River, which is significant due to the presence of two major industries-a paper mill and a cement factory. The other significant feature is the conveyors that travel from India to Chattak. This study involves determination of physical, biological and chemical parameters of surface water at different points. The river was found to be highly turbid in the monsoon season. But BOD and fecal coliform concentration was found higher in the dry season. The water was found slightly acidic. The mean values of parameters were Conductivity 84-805µs; DO: dry-5.52 mg/L, monsoon-5.72 mg/L; BOD: dry-1 mg/L, monsoon-0.878 mg/L; Total Solid: dry-149.4 mg/L, monsoon-145.7 mg/L. A model study was also conducted and values of different model parameters were estimated.

BackgroundAbscisic acid (ABA) and sucrose act as molecular signals in response to abiotic stress. However, how their synergy regulates the source-sink relationship has rarely been studied. This study aimed to reveal the mechanism underlying the synergy between ABA and sucrose on assimilates allocation to improve grain yield and quality of rice. The early indica rice cultivar Zhefu802 was selected and planted in an artificial climate chamber at 32/24 °C (day/night) under natural sunlight conditions. Sucrose and ABA were exogenously sprayed (either alone or in combination) onto rice plants at flowering and 10 days after flowering.ResultsABA plus sucrose significantly improved both the grain yield and quality of rice, which was mainly a result of the higher proportion of dry matter accumulation and non-structural carbohydrates in panicles. These results were mainly ascribed to the large improvement in sucrose transport in the sheath-stems in response to the ABA plus sucrose treatment. In this process, ABA plus sucrose significantly enhanced the contents of starch, gibberellic acids, and zeatin ribosides as well as the activities and gene expression of enzymes involved in starch synthesis in grains. Additionally, remarkable increases in trehalose content and expression levels of trehalose-6-phosphate synthase1, trehalose-6-phosphate phosphatase7, and sucrose non-fermenting related protein kinase 1A were also found in grains treated with ABA plus sucrose.ConclusionThe synergy between ABA and sucrose increased grain yield and quality by improving the source-sink relationship through sucrose and trehalose metabolism in grains.

Surma River is polluted day by day by human activities, poor structured sewerage and drainage system, discharging industrial and household wastes. The charas (natural channels) are responsible for surface runoff conveyance from its urban catchments to the receiving Surma River. Water samples have been collected from a part of Surma River along different points and analyzed for various water quality parameters during dry and monsoon periods. Effects of industrial wastes, municipal sewage, and agricultural runoff on river water quality have been investigated. The study was conducted within the Chattak to Sunamganj portion of Surma River, which is significant due to the presence of two major industries--a paper mill and a cement factory. The other significant feature is the conveyors that travel from India to Chattak. The river was found to be highly turbid in the monsoon season. But BOD and fecal coliform concentration was found higher in the dry season. The water was found slightly acidic. The mean values of parameters were Conductivity 84-805 micros; DO: dry-5.52 mg/l, monsoon-5.72 mg/l; BOD: dry-1mg/l, monsoon-0.878 mg/l; Total Solid: dry-149.4 mg/l, monsoon-145.7 mg/l. In this study, an effort has been taken to investigate the status of concentration of phosphate (PO(-4)) and ammonia-nitrogen (NH4-N) at four entrance points of Malnichara to the city, Guali chara, Gaviar khal and Bolramer khal. Data has been collected from March-April and September-October of 2004. Concentrations have been measured using UV Spectrophotometer. Although the phosphate concentration has been found within the limit set by DOE for fishing, irrigation and recreational purposes, however ammonia-nitrogen has been found to exceed the limit.

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