Effect of Irrigation, Mulch and Nitrogen on Yield and Composition of Japanese Mint (Mentha arvensis L. subsp. haplocalyx var. piperascens) Oil

Effects of irrigation, mulch and nitrogen on yield and composition of Japanese mini ( Mentha arvensis L. subsp. haplocalyx Briq. var piperascens) oil were studied using a replicated experiment. Two harvests were obtained 120 davs atter planting and 75 davs after the first harvest. Significantly higher drv matter and essential oil yields were obtained with frequent irrigations (50 mm Cumulative Pan Evaporation), application of mulch and Nitrogen. The economic optimum rate of N was 215 Kg ha^-1. The essential oil from the first harvest was richer in menthol (78.8%) than the oil obtained from second harvest (75.2%). Soil moisture extraction was maximum between 15 and 30 cm soil depths. Consumptive use, water use efficiency and moisture use rate-were maximum under higher irrigation levels and mulch application which reflect that more availability of moisture in soil profile with frequent irrigations and application of mulch.     

Ultrastructure of the host-pathogen interface of Peronospora viciae in cultivars of pea which show different susceptibilities

The ultrastructure of interactions of pea downy mildew ( Peronospora viciae ) on the leaves and petioles of two cultivars of pea, Superb and Maro, was examined. Tissue fixed at the time of sporulation (10 days after inoculation) revealed that many of the intercellular hyphae in Maro were showing evidence of partial or complete autolysis. The penetration matrices were enclosed in a thicker layer of callose-like material than in Superb, and many of the haustoria had collapsed, distorted profiles. Analysis of organelles lying close to the extra haustorial membrane revealed fewer associations with endoplasmic reticulum in Superb.     

Is celery yellow net c used by parsnip yellow fleck virus

Celery yellow net w s described by Hollings (1964) s severe dise se of celery (Apium graveolens L. var. duke (Miller) DC.) that could be transmitted by grafting nd occasionally by mechanical inocul tion with leaf extracts. Pemberton & Frost (1986) observed similar symptoms in celery crops. but were unable to isolate the causal agent.
During recent attempts to isolate the causal gent of celery yellow-spot, another disease previously reported by Hollings (1964) and Pemberton & Frost (1986), we found that two of our samples from crop in Cheshire contained different virus. As well as yellow spots, these two plants also had yellow-net symptoms on the older leaves, and one of the plants was stunted with some distortion of the young leaflets. The two virus isolates appeared identical from extensive testing on range of herbaceous indicator plants, so one of them, CV506, w s selected for further study     

Complementation between genes for resistance to race 1 of Fusarium oxyspomm f.sp. ciceri in chickpea

The reactions of parents and F₁ and F₂ generations of crosses of chickpea cultivars K-850 with C-104 and JG-62 and F₃ progenies of K-850 × C-104 to race 1 of Fusarium oxysporum f.sp. ciceri were studied. The results indicate that K-850 carries a recessive allele for resistance at a locus different from and independent of that carried by C-104 and recessive alleles at both loci together confer complete resistance. The possible contribution of this recessive gene to late wilting in K-850 is discussed. These observations have important implications in breeding for resistance to wilt in chickpea.     

Sheath rot and leaf blight – a new disease of Java citronella caused by Rhizoctonia solani

A new disease of Cymbopogon winterianus , characterized by symptoms of sheath rot and leaf blight, has been observed in the Tarai region of Uttar Pradesh (IN). The pathogen has been isolated and identified as Rhizoctonia solani.     

Effects of isoproturon on photosynthesis in susceptible and resistant biotypes of Phalaris minor and wheat

Wheat (cv. WH-147) and five biotypes of Phalaris minor Retz. (KR-1, H-4, K-2, H-2 and J-1) were treated with isoproturon in controlled environmental conditions to assess their level of resistance. Resistance of P. minor to isoproturon was found in the order of KR-1 > H-4 > K-2 > H-2 = J-1. Compared with the susceptible (S) biotype (H-2), the resistant (R) biotypes (KR-1. H-4 and K-2) of P. minor required 13.0, 4.5 and 2.7 times higher doses of isoproturon for a 50% reduction in growth (GR₅₀) and 2.4 times that of the S biotype (H-2) by wheat. The corresponding figures for KR-1, H-4, K-2 biotypes and wheat were 18, 4.1, 2.4 and 4.6 times based on dry weight reduction. The effect of isoproturon on photosynthesis was studied in vitro using five biotypes of P. minor and in viro with wheat. KR-1 (R) and H-2 (S) biotypes of P. minor. Under in vitro treatment conditions isoproturon inhibited the photosynthesis of all five P. minor biotypes, whereas in vivo the recovery was greater in the R biotype than in the wheat and the S biotype. Effects on chlorophyll fluorescence were also measured in wheat and the KR-1 (R) and H-2 (S) biotypes of P. minor. A 4-h treatment of excised leaves incubaled in isoproluron solution (0.025 and 0.05 mm concentration) resulted in a decreased fluorescence coefficient (F_v F_m ratio in which F_v= variable fluorescence (F_m - F^o): F_m= the maximum fluorescence and F_o= initial fiuorescence) in wheat (Triticum aestivum L.) and both biotypes of P. Minor. The recovery was, however, greater in the R biotype than in wheat and it was completely recovered within 24 h. No recovery was recorded in the case of the S biotype of P. minor and a greater recovery time was required for wheat than the R biotype. The higher dose required for growth inhibition in the R biotype and rapid recovery of oxygen evolution and fluorescence coeflicient under in viro conditions together with the absence of selectivity in vitro suggests that the target site was unaffected. It can be conjectured that resistance to isoproturon is most probably because of enhanced metabolism or sequestration of isoproturon, resulting in decreased target site delivery.     

Long-term conservation agriculture and intensified cropping systems: Effects on growth, yield, water, and energy-use efficiency of maize in northwestern India

Conservation agriculture(CA)-based best-bet crop management practices may increase crop and water productivity, while conserving and sustaining natural resources. We evaluated the performance of rainy season maize during 2014 under an ongoing long-term trial(established in 2008) with three tillage practices, i.e., permanent bed(PB), zero tillage(ZT), and conventional tillage(CT) as main plots, and four intensified maize-based cropping systems, i.e., maize-wheat-mungbean, maize-chickpea-Sesbania(MCS), maizemustard-mungbean, and maize-maize-Sesbania) as subplot treatments. In the seventh rainy season of the experiment, maize growth parameters, yield attributes, yield, and water-and energy-use efficiency were highest at fixed plots under ZT. Maize growth parameters were significantly(P 0.05) superior under ZT and PB compared with CT. Maize yield attributes, including cobs per m~2(7.8), cob length(0.183 m), grain rows per cob(13.8), and grains per row(35.6), were significantly higher under ZT than CT; however, no significant effect of cropping systems was found on maize growth and yield attributes. Zero tillage exhibited the highest maize productivity(4 589 kg ha~(-1)). However, among the cropping systems, MCS exhibited the highest maize productivity(4 582 kg ha~(-1)). In maize, water use was reduced by 80.2–120.9 mm ha-1under ZT and PB compared with CT, which ultimately enhanced the economic water-use efficiency by 42.0% and 36.6%, respectively. The ZT and PB showed a 3.5%–31.8% increase in soil organic carbon(SOC) at different soil depths(0–0.45 m), and a 32.3%–39.9% increase in energy productivity compared with CT. Overall, our results showed that CA-based ZT and PB practices coupled with diversified maize-based cropping systems effectively enhanced maize yield and SOC,as well as water-and energy-use efficiency, in northwestern India.     

China-CIMMYT collaboration enhances wheat improvement in China

China and CIMMYT have collaborated on wheat improvement for over 40 years and significant progress has been achieved in five aspects in China. A standardized protocol for testing Chinese noodle quality has been established with three selection criteria, i.e., gluten quality, starch viscosity and flour color are identified as being responsible for noodle quality. Genomic approaches have been used to develop and validate gene-specific markers, leading to the establishment of a KASP platform, and seven cultivars have been released through application of molecular marker technology. Methodology for breeding adult-plant resistance to yellow rust, leaf rust and powdery mildew, based on the pleiotropic effect of minor genes has been established, resulting in release of six cultivars. More than 330 cultivars derived from CIMMYT germplasm have been released and are now grown over 9% of the Chinese wheat production area. Additionally, physiological approaches have been used to characterize yield potential and develop high-efficiency phenotyping platforms. CIMMYT has also provided valuable training for Chinese scientists. Development of climate-resilient cultivars with application of new technology will be the priority for future collaboration.     

Impact of irrigation regimes on regeneration and growth of Prosopis cineraria in arid areas of Indian Thar

An experiment was initiated in 2008 to evaluate the impact of irrigation regimes on germination and growth patterns of seedlings of Prosopis cineraria in the arid areas of Thar, India. Seeds collected from dried pods of P. cineraria were sown in polybags placed in nursery beds. Different irrigation regimes were provided to different beds and data regarding germination and growth were recorded to study natural regeneration. The study revealed that irrigation regimes significantly affected the germination and growth of P. cineraria under nursery conditions. The germination rate declined as the irrigation regime shifted from a daily to a fortnightly basis. Height of the seedlings also declined with a decrease in the intensity of irrigation. Thus, it can be concluded that germination and growth of seedlings of P. cineraria under nursery conditions can be enhanced by providing irrigation at regular intervals.     

印度热带森林干旱扰动土壤的微生物碳, 氮, 磷的研究

Variations in microbial biomass C (MB-C),N (MB-N) and P (MB-P) along a gradient of different dominant vegeta- tion covers (natural forest,mixed deciduous forest,disturbed savanna and grassland ecosystems) in dry tropical soils of Vindhyan Plateau,India were studied from January 2005 to December 2005.The water holding capacity,organic C,total N,total P and soil moisture content were comparatively higher in forest soils than in the savanna and grassland sites.Across different study sites the mean annual MB-C,MB-N and MB-P at 0-15 cm soil depth varied from 312.05 ± 4.22 to 653.40 ± 3.17,32.16 ± 6.25 to 75.66 ± 7.21 and 18.94 ± 2.94 to 30.83 ± 23.08 μg g ?1 dry soil,respectively.At all the investigated sites,the maximum MB-C,MB-N and MB-P occurred during the dry period (summer season) and the minimum in wet period (rainy season).In the present study,soil MB-C,MB-N and MB-P were higher at the forest sites compared to savanna and grassland sites.The differences in MB-C,MB-N and MB-P were significant (P 0.001) among sites and seasons.The MB-C (P 0.0001),MB-N (P 0.001) and MB-P (P 0.0001) were positively correlated with organic C,while the relationship between soil moisture and MB-C,MB-N and MB-P (P 0.001,P 0.01 and P 0.0001,respectively) was negative.The decreasing order of MB-C,MB-N and MB-P along study ecosystems was natural forest mixed deciduous forest savanna grassland.The results suggested that deforestation and land use practices (conversion of forest into savanna and grassland) caused the alterations in soil properties,which as a consequence,led to reduction in soil nutrients and MB-C,MB-N and MB-P in the soil of disturbed sites (grassland and savanna) compared to undisturbed forest ecosystems.