Crop Cycle Length Determines Optimal Transplanting Date for Seedlings from Hybrid True Potato Seeds

The technology of hybrid breeding in diploid potatoes creates opportunities to design novel and improved cultivation systems based on hybrid true potato seeds. A promising cultivation pathway to produce seed or ware tubers is by transplanting greenhouse-raised seedlings into the field. This study explored the effects of transplanting date and seedling age on tuber yield, using greenhouse-raised seedlings. Field trials with experimental hybrid genotypes were conducted in three consecutive years. In 2017 and 2018, 4- and 6-week-old seedlings were transplanted at four dates: March, April, May and June. In 2019, transplanting dates included April, May and June and seedling age was 5 weeks. In 2018, the March planting experienced severe frost during the initial field period resulting in crop failure. In 2017 and 2019, plants could withstand shorter and less severe frost events. Seedling age did not significantly affect tuber parameters. Transplanting in June resulted in lower marketable yield (> 28 mm) compared with earlier transplanting dates when crops were harvested in September. At full crop senescence, no differences in marketable yield were observed. The optimal transplanting window, taking into account weather-related risks, is approximately between early April and end May. For some genotypes, crop cycle length was observed to be a more important yield-determining factor than transplanting date.

Influence of seedling age on growth, productivity and heat use efficiency of rice genotypes in North West India

An experiment was conducted at Punjab Agricultural University, Ludhiana, India during kharif 2017 and 2018 to determine the effect of seedling age on growth, phenology and thermal energy utilization by different rice genotypes. The field experiment was laid–out in factorial RCBD design keeping three seedling age (25, 35, 45 days) and four rice genotypes (PR 121, PR 122,PR 124, PR 126) with three replicates. The prevalence of dry weather conditions especially during September month of 2017, which coincides with graingrowth phase was congenial for rice crop and was reflected in the yield and yield attributes. There was consistent decline in grain and straw yield of rice with increase in seedling age due to reduced leaf area index (LAI), dry matter partitioning to grain/culm and SPAD value. This may be due to prevalence of higher range of minimum temperature resulting into more respiratory losses and thereby leading to lower heat use efficiency. Among genotypes, PR 126 was found to be most heat use efficient owing to its shorter duration (93.9 days), where as PR 121 and PR 122 recorded the highest grain and straw yield due to higher accumulation of growing degree and more congenial temperature leading to more number of panicles m-2 along with the bold grains. It was also observed that increasing seedling age beyond 25 days caused sharp decline in grain and straw yield of PR 124 and PR 126 through effect on panicles m-2,SPAD value and AGDD; while PR 121 and PR 122 gave similar yield when transplanted using 25 to 45 days older seedlings. Harvest index did not differ due to various treatments.

Quantitative Assessment of Abiotic Stress on the Main Functional Phytochemicals and Antioxidant Capacity of Wheatgrass at Different Seedling Age

The wheat seedlings of 6 days old were daily subjected to ultraviolet irradiation (irradiating for 5, 10, 20, 40, and 60 min/day, respectively), Polyethylene glycol 6000 (5, 10, 15, 20, 25% in 1/2 Hoagland solution, respectively), and salinity solution (10, 25, 50, 100, 200 mM in 1/2 Hoagland solution, respectively), while the control group (CK) was supplied only with the Hoagland solution. The wheatgrass was harvested regularly seven times and the total soluble polysaccharides, ascorbic acid, chlorophyll, total polyphenol, total triterpene, total flavonoid, and proanthocyanins content were tested. The antioxidant capacity was evaluated through 2,2′-azino-bis (3-ethylbenzthia-zoline-6-sulfonic acid) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability, and ferric ion reducing power. Technique for order preference by similarity to ideal solution (TOPSIS) mathematical model was adopted to comprehensively assess the functional phytochemicals of the different treatments. The results showed that the accumulation patterns of phytochemicals under abiotic stress were complex and not always upregulated or downregulated. The antioxidant activity and functional phytochemicals content of wheatgrass were significantly affected by both the stress treatments and seedling age, while the latter affected the chemicals more efficiently. The top five highest functional phytochemicals were observed in the 200 mM NaCl treated group on the 21st and 27th day, 25% PEG treated group on the 24th day, 200 mM NaCl treated group on the 24th day, and the group of 40 min/day ultraviolet exposure on 27th day.

Role of temperature, seedling-age and soil moisture on collar rot disease in lentil caused by Sclerotium rolfsii and identification of resistance sources

Collar rot disease caused by Sclerotium rolfsii attacks lentils at the seedling stage and reduces plant population considerably in the field. Although soil moisture and temperature influence disease development much, no concrete attempts to find the optimum level of moisture, temperature, and seedling age have been made in lentils. Here, we identified optimum soil moisture, temperature, and seedling age that allow successful infection by S. rolfsii and maximum seedling mortality in a controlled environment inside a plant growth chamber. Screening of one hundred and ninety genotypes for two consecutive years in the field identified some resistant genotypes. Ten genotypes were selected from earlier screening and further evaluated in sick plots at two different locations with different pH for three consecutive years. About 80% variation in disease resistance was due to genotypes, and minor infection of collar rot disease was observed in acidic lateritic soil than in neutral alluvial soil. Furthermore, low mycelial load in a selected resistant genotype was confirmed by quantitative real-time PCR using an S. rolfsii specific primer pair. The identified resistant genotypes will be helpful to breeding collar rot resistant cultivars and mapping disease resistance. In addition, the study improves the understanding of the development of collar rot disease, which is critical for expanding the area under cultivation in Asia, especially in rice fallows.

Effect of spacing and seedling age on yield, quality and heat use of scented rice in lower gangetic plains of West Bengal

A traditional scented rice (cv. Radhunipagal) was tested under varied spacing (20 cm × 20 cm, 20 cm × 15 cm, 15 cm × 15 cm and 20 cm × 10 cm) and seedling age (25, 35 and 45 days) during wet (kharif) season of 2018 at B.C.K.V., Nadia, West Bengal. Seedling age caused significant variation in life duration and summed GDD from 147.9 days and 2436°C day (25-day aged) to 162.0 days and 2753°C day (45-day aged), but with maturity in same meteorological week. Square planting (15 cm × 15 cm or 44 hills m-2) resulted in highest grain yield (2.52 t ha-1), which was 2.85, 11.01 and 4.56% greater over wider (20 cm × 15 cm and 20 cm × 20 cm) and closer spacings (20 cm × 10 cm). Radhunipagal rice raised with 25-days old seedlings recorded the highest grain yield (2.53 t ha-1) and maximum heat use efficiency (0.90 kg ha-1 °C day-1), and that yield was 0.12 and 0.22 t ha-1 greater over the crops planted with 35 and 45-days old seedlings during wet season. Spacing could not influence the cooking and processing quality (gelatinization temperature, kernel elongation ratio and aroma) except protein content of milled rice in the study. Radhunipagal paddy planted with 45-day aged seedlings recorded maximum protein content (6.36%) and alkali spreading value (score 3.27).