Probir Kumar Ghosh

Agriculture in India is facing several challenges which together are manifested into the sustainability issues. The broad contours of the agricultural production system in the country have been defined by the need to achieve food security which calls for close attention to rice–wheat (Triticum aestivum L.) cropping system of the Indo Gangetic Plains (IGP) whose sustainability is under threat. Degradation of natural resources, severe biotic and abi otic stresses specially drought, floods, pest infestations with accompanying impacts on biodiversity and agricultural productivity are the major constraints to agricultural development. Further, climate change has gained significant global attention over the past decade due to concerns of deleterious long-term impacts on agriculture, water sup ply, human welfare, regional and political stability. All the related issues need to be addressed on priority, with par ticular emphasis on soil-carbon through a holistic approach. As the strategy brings focus on income of farmers, the agricultural technology needs to move from “Production oriented-Green Revolution” to “Farmer’s Income oriented Revolution” and environmentally sustainable farming. Therefore, for long-term sustainability in agriculture, 4 pil lars/ components (good agricultural practices, climate-change mitigation and adaptation, diversification of high value crops and biodiversity management) needs to be addressed properly, more importantly good agricultural practices (GAP). The GAPs are based on the principles of risk prevention, risk analysis, sustainable agriculture, and integrated crop management (ICM), which are of utmost importance in present time. The GAPs for agricultural sustainability are reduced tillage, conservation agriculture, resource-conservation technologies (RCTs), erosion control measures, diversified cropping system, micro-irrigation, balanced fertilization, manuring, watershed man agement, organic farming, and integrated farming systems etc. Now that the vision is to impart income security to the farmers of the country, diversification of the system across all the sub-sectors of agriculture assumes impor tance which is, indeed a de-risking mechanism capable of negotiating both endogenous and exogenous risks as sociated with the system. The effective and efficient management of agro-biodiversity is also essential through management of genebanks, science-led innovations; livelihood, food and nutrition security though crop diversifica tion, use of lesser-known crops and wild relatives in crop improvement; dealing appropriately with quarantine, bio safety and bio-security.

Yellow mosaic disease of Cajanus scarabaeoides (L.) Thouars (CsYMD) was observed in up to 46% of C. scarabaeoides plants in the mungbean, urdbean, and pigeon pea fields from 22 districts of Chhattisgarh State, India, during 2017 to 2019. The symptoms were characterized by yellow mosaic on green leaves and yellow discoloration of leaves in advanced stages of the disease. Severely infected plants showed shortened internodal length and reduced leaf size. CsYMD was transmissible to healthy C. scarabaeoides and C. cajan by whitefly (Bemisia tabaci). The infected plants developed typical yellow mosaic symptoms on their leaves within 16 and 22 days of inoculation, respectively, suggesting a begomovirus etiology. Molecular analysis revealed that this begomovirus has a bipartite genome composed of DNA-A (2,729 nucleotides) and DNA-B (2,630 nucleotides). Sequence and phylogenetic analyses revealed that the nucleotide sequence of the DNA-A component had the highest identity of 81.1% with DNA-A of Rhynchosia yellow mosaic virus (RhYMV; NC_038885), followed by mungbean yellow mosaic virus (MN602427; 75.3%). DNA-B had the highest identity of 74.0% with DNA-B of RhYMV (NC_038886). As per ICTV guidelines, this isolate had <91% nucleotide identity with DNA-A of any of the begomoviruses reported; so, it is proposed as a new begomovirus species, tentatively named C. scarabaeoides yellow mosaic virus (CsYMV). After agroinoculation with DNA-A and DNA-B clones of CsYMV, all Nicotiana benthamiana plants developed leaf curl symptoms along with light yellowing symptoms 8 to 10 days after inoculation (DAI), while ∼60% of the C. scarabaeoides plants developed yellow mosaic symptoms similar to those observed in the field 18 DAI, thus fulfilling Koch’s postulates. From these agro-infected C. scarabaeoides plants, CsYMV was transmissible to healthy C. scarabaeoides plants by B. tabaci. Apart from these hosts, CsYMV also infected and caused symptoms in mungbean and pigeon pea.

Study of appropriate planting time and response to agronomic management practices is imperative for the newly introduced cactus pear (Opuntia ficus-indica (L.) Mill.) into a semi-arid region of India. Responses of cactus pear to agronomic practices (planting time and irrigation and fertilizer application) were evaluated to determine the potential for fodder production and livestock feed in a semi-arid environment of India. We assessed four planting times (February, March, July and October) and two agronomic managements (with and without irrigation and fertilizer application) during 2016–2020 at Jhansi, India. Cactus pear establishment and growth improved with planting time in July and October due to favorable soil moisture and congenial temperature. However, plant height (19 cm) and cladode weight (118 g) were greater in July than in October planting. Nutrient uptake and crude protein contents, however, were higher for the earlier plantings of February and April compared to June and October. Irrigation and nutrients application had little effect on the cactus pear plant growth, except on plant width and cladode length and width. Cactus pear can be planted during July in moderately fertile soils without any agronomic intervention in semi-arid situations of India and has potential as an effective alternative source of forage for livestock during the summer months.