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The rhizosphere is a dynamic region influenced by complex interactions between plants and microbes that are closely linked to the metabolically active hotspots of the roots below the soil and participate in below-ground interactions. We must consider the roles of the rhizosphere to improve above-ground productivity and hence regulate the environment. Initially, the soil was measured to be stable only based on nutrient abundance, but the healthy soil is now seen with large microbial communities after rhizosphere evolution. In this regard, numerous strategies for manipulating the rhizosphere for better ecological functioning need to be developed. Based on current ecological evidence, we propose a new sketch in which future comparative research through sustainable agriculture and an environment is required to uncover the underlying mechanisms. Plant roots manage below-ground diversity by releasing exudates into the rhizosphere, due to their microbial growth capability. The microbes are attracted to the exudates, and in the rhizosphere, they developed communities. Roots play an important role in the microbial community establishment, having a major and primary energy channel in the ecosystem of the rhizosphere. Via the roots channel, the energy release then transfers to the microbial channel, eventually converted into microbial biomolecules, which are then returned to the above-ground in the form of volatile compounds and productivity. This review discusses the different energy channels in the rhizosphere that facilitate the development of the microbial community and the transfer of energy in a sequence in the form of productivity from above-ground to below-ground to above-ground. Importantly, such awareness may result in strategies for improving plant health and development in the context of future agricultural demand.

Arbuscular mycorrhiza (AM), plant growth promoting rhizobacteria (PGPRs) and root-knot nematode survive in the rhizosphere and perform the same niche. AM and PGPRs play positive role in roots while nematode oppose it. Nematode damages the root system, which reduces the nutrient uptake specially phosphorus (P) while AM help to uptake. PGPRs are another symbiotic micro-organism helpful to mycorrhizal survival and colonization. AM and PGPRs can defeat the soil borne diseases like root-knot disease which lead to increasing mycorrhizal colonization and nutrient uptake. On this basis current work emphasizes the effects on mycorrhizal colonization and P uptake in presence of PGPRs along with root-knot nematode infection in tomato plants.

Arbuscular mycorrhizal fungi (AMF) and plant growth promoting rhizobacteria (PGPR) have potential to control soil-borne diseases including plant-parasitic nematodes. First, the effects of dual inoculation of mycorrhiza (Rhizophagus irregularis) and two stains of pseudomonads (Pseudomonas jessenii strain R62 and Pseudomonas synxantha strain R81) on tomato (Solanum lycopersicum cv. PT-3) growth were tested. Further, the physiological and biochemical changes caused by these beneficial organisms during infection by the root-knot nematode Meloidogyne incognita were studied. The experiment was conducted under glass house conditions and carried out up to one month after nematode inoculation. Plants treated with dual or individual inoculation of AMF and PGPR showed significantly enhanced plant growth and reduced nematode infection. In addition, they exhibited potent activity of phenolics (28 %) and defensive enzymes i.e. peroxidase (PO; 1.26 fold), polyphenyloxidase (PPO; 1.35 fold) and superoxide dismutase (SOD; 1.09 fold) while a significant reduction in malondialdehyde (MDA; 1.63 fold) and hydrogen peroxide (H2O2; 1.30 fold) content was recorded when compared to the nematode-infected plants. These findings indicate the feasibility of AMF and PGPR individually or in combinations as potential biocontrol agents for the management of root-knot nematodes.

Rice is one of the widely consumed staple foods among the world's human population. Its production is adversely affected by high temperature and is more pronounced at flowering stage. Elucidating elevated temperature stress-related proteins as well as associated mechanisms is inevitable for improving heat tolerance in rice. In the present study, a proteomic analysis of heat-sensitive rice genotype, IET 21405 was conducted. Two-dimensional electrophoresis (2-DE) and MALDI-TOF/MS-based proteomics approaches revealed a total of 73 protein spots in rice leaf. The protein profiles clearly indicated variations in protein expression between the control and heat treated rice genotypes. Functional assessment of 73 expressed proteins revealed several mechanisms thought to be involved in high temperature including their putative role in metabolism, energy, protein synthesis, protein transport/storage, etc. Besides these, some proteins are expected to involve in photosynthesis, tricarboxylic acid (TCA) cycle, glycolysis and other proteins for energy production. The proteins identified in the present study provide a strong basis to elucidate gene function of these proteins and to explain further the molecular mechanisms underlying the adaptation of rice to high temperature stress.

The article Mycorrhizal colonization and phosphorus uptake in presence of PGPRs along with nematode infection, written by Ishwar Prakash Sharma and A. K. Sharma, was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 20 September 2018 with open access.

Results of experiments conducted in T-maze to probe the functional role of conspecific odours indicated that whereas the male Indian gerbil,Tatera indica indica invariably prefers odours (from their body, that of the sebum exudation of scent marking gland, urine and faecal matter) of strange males, the females with and devoid of the scent marking gland show slight preference for male odours. However, all the categories ofTatera indica placed their preference for their own odours at the lowest. This behaviour suggests that the role of scent marking to label the habitat for its own use or to signal ‘home’ to the marking animal may not be the sole function of scent marking in this species. It is quite possible that in the desert grassland, scent marking is being used for maintaining a minimum distance between two animals or pairs, as exhibited by the diversity in the occurrence of the scent gland in the field (pair-tolerant) and urban (gregarious social organisation) populations ofTatera indica. This type of spatial distribution, maintained by scent marking behaviour, may be important to withstand the low carrying capacity of the aridland which suffers from almost a perpetual paucity of food.

The two gerbils,Tatera indica andMeriones hurrianae, and the metad,Rattus meltada pallidior exhibit significant monthly variations in the dimension (maximum length X maximum breadth) of the ventral scent marking gland. Peaks in gland size occur late in winter and monsoon which generally correspond to the maximum breeding activity of these rodents during the year. However, the monthly averages of gland area and incidence of pregnancy in the three species do not follow the same trend. It is difficult, therefore, to conclude if the scent-marking behaviour and the breeding performance of the rodents are inter-related.

Brodifacoum, chlorophacinone and coumatetralyl treated pearl millet (Pennisetum typhoides) grains were tested in a desert scrub grassland to evaluate the comparative field efficacy of these three anticoagulant rodenticides. Baits were placed for 10 consecutive days in bait stations in 18 plots of one hectare each in a randomized block design. Per cent reduction in rodent population was calculated by pre and post-treatment active burrow counts, census baiting and live trapping. Results revealed that brodifacoum is significantly more effective than other two anticoagulants. However, analysis of variance revealed significant difference in the estimation of per cent reduction in the rodent population calculated by three methods, the possible reasons for which are also discussed.

In a choice test, the Indian gerbils,T. indica preferred urine-mixed food over ordinary millet indicating a phago-stimulant nature of conspecific urine. The experiments also revealed that addition of conspecific urine mitigates the poison aversion and bait shyness behaviour significantly, as a result of which zinc phosphide poisoning can be attempted a second time in a sequence, thus enhancing the control success.T. indica showed a clear preference for urine of the same sex which suggests that the active attractant in the urine has no sex attraction.

Warfarin was evaluated in laboratory against Indian gerbil,Tatera indica and desert gerbil,Meriones hurrianae. Chronic LD50 for the two species was found to be 4 × 19·1 and 4 × l5·9mg/kg respectively. Feeding for 14 days on 0·025% warfarin treated bait provided complete kill in the gerbils but the poisoned bait was less palatable than the plain bait. A period of 18 and 19 days feeding on 0·025% waifarin bait was found suitable to detect resistance to warfarin amongT. indica andM. hurrianae respectively.

Behavioural responses of the Indian gerbil,Tatera indica, to conspecific sebum odour of the male ventral marking scent gland were studied in a glass cage and a plus maze. Male and female gerbils were attracted towards the strange male sebum odour though its magnitude was low in females possessing the ventral marking gland, still lower in the females in which the marking gland was absent. The diversity in preferential behaviour of femaleTatera indica is discussed in relation to the role of ventral marking behaviour in chemical communication among rodents. Correlating the results of the experiments with our field observations, it appears that the function of scent marking inT. indica is more of a ‘familiarisation’ nature to label the habitat for its own use in orientation or to signal ‘home’ to the marking animal.