Establishment of optimal terms and methods for growing seed fruits of the new line LZ-2513 squash in the Tashkent region of Uzbekistan

Изучение кабачка (Cucurbita pepo var. giraumontia) в природно-климатических условиях Узбекистана и совершенствование технологии выращивания семенных плодов – важное направление селекционной работы по обогащению сортимента овощных культур и организации семеноводства этой культуры. Цель исследований: установить оптимальные сроки высева семян и посадки рассады перспективной линии короткоплетистой формы кабачка LZ-2513 при весеннем сроке выращивания на семенные цели. Исследования проводили в 2016 и 2019 годах на экспериментальном участке Научно-исследовательского института овощебахчевых культур и картофеля Республики Узбекистан (Ташкентский район Ташкентской области). Климат региона схож с условиями большинства овощеводческих хозяйств, расположенных в равнинной центральной части Узбекистана. Почвы опытного участка – типичные суглинки, окультуренные, влагоемкие, глубина залегания грунтовых вод – более 6–7 м, количество гумуса в почве – 0,641–0,943%, азота – 0,072–0,121%, фосфора – 0,130–0,171% и калия – 1,627–2,206%. Погодные условия 2016 и 2019 годов были благоприятными для роста и развития кабачка, за исключением засушливого июля и августа, в течение которых недостаток влаги компенсировали поливами. Испытаны четыре весенних срока посева и посадки рассады (в 2016 году – 3 апреля, 12 апреля, 20 апреля и 1 мая; в 2019 году – 1 апреля, 10 апреля, 21 апреля и 30 апреля). Делянки двухрядковые, длиной 10 м, схема размещения (140+70)/2×50 см. Площадь учетной делянки 21,0 м2. На каждой делянке размещались по 40 растений, повторность опыта четырехкратная. Установлено, что в условиях Ташкентской области Узбекистана наибольший выход семян из плодов у линии LZ-2513 был при выращивании кабачка рассадным способом в первой декаде апреля (в начале I и II декады апреля), а при безрассадной культуре – при посеве семян в начале апреля, что связано с наиболее благоприятными температурными условиями для культуры кабачка. The study of squash (Cucurbita pepo var. giraumontia) in the natural and climatic conditions of Uzbekistan and the improvement of the technology of growing seed fruits is an important direction of breeding work is to enrich the assortment of vegetable crops and the organization of seed production of this crop. The purpose of the research: to establish the optimal timing of sowing seeds and planting seedlings of a promising line of short-leafed squash LZ-2513 at the spring period of cultivation for seed purposes. The research was carried out in 2016 and 2019 at the experimental site of the Scientific Research Institute of Vegetable and melon crops and Potato of the Republic of Uzbekistan (Tashkent district of the Tashkent region). The climate of the region is similar to the conditions of most vegetable farms located in the flat central part of Uzbekistan. The soils of the experimental site are typical loams, cultivated, moisture-intensive, the depth of groundwater is more than 6–7 meters, the amount of humus in the soil is 0.641–0.943%, nitrogen – 0.072–0.121%, phosphorus – 0.130–0.171% and potassium – 1.627–2.206%. Weather conditions in 2016 and 2019 were favorable for the growth and development of squash, with the exception of dry July and August, during which the lack of moisture was compensated by watering. 4 spring sowing and planting dates have been tested (in 2016 – April 3, April 12, April 20 and May 1; in 2019 – April 1, April 10, April 21 and April 30). Two-row plots, 10 m long, layout (140+70)/2×50 cm. The area of the accounting plot is 21.0 m2. 40 plants were placed on each plot, the repetition of the experiment was fourfold. It was found that in the conditions of the Tashkent region of Uzbekistan, the highest yield of seeds from fruits of the LZ-2513 line was established when squash was grown by seedling method in the first decade of April (at the beginning of the first and second decade of April), and with seedless culture – when sowing seeds in early April, which is associated with the most favorable temperature conditions for squash culture.

Response of yam varieties to soil moisture regime in Southwestern Nigeria

A field experiment was conducted on varietal response of white yam to moisture regime in Abeokuta. The experiment comprised three varieties of yam (Efuru, Ise-osi and Oniyere), three mulching options (grass, polythene and unmulched), and two planting dates (early and late). Treatments were replicated three times using RCBD lay-out. Model for selecting planting date involved relating potential evapotranspiration (PE) to precipitation (P) in the form of 0.1PE<P < 0.5PE, partitioned for attaining optimal planting date into early {T1= Σ(P-0.1PE) ≤ 0} and late {T2 = Σ(P-0.5PE) ≤ 0}, respectively. For humid period defined by P> PE, the physiological parameters and moisture agro-climatic indices measured during phenological stages of yam grown were analyzed with respect to treatments. Result showed that T1 defined as Σ(P-0.1PE) ≤ 10 mm appeared as the best model that significantly (P < 0.05) influenced emergence rate, phenological growth and tuber yield. All yam varieties evaluated were suitable for planting with respect to yield. Efuru and Ise-osi synchronized perfectly with Actual Water Availability and produced good vegetative growth with LAI of 1.08 and 0.91 leading to higher tuber yield of 12 and 11.64 tonnes ha-1, respectively. Grass mulch had tuber yield, 4-6 tonnes ha-1greater than the polythene and unmulched plots in all varieties. Mulching significantly (P< 0.05) increased tuber yield, 6-8 tonnes ha-1than the unmulched. Conclusively, early planting with grass mulch increased tuber yield.

Adaptation Potential of Current Wheat Cultivars and Planting Dates under the Changing Climate in Ethiopia

Global warming poses a severe threat to food security in developing countries. In Ethiopia, the primary driver of low wheat productivity is attributed to climate change. Due to the sparsity of observation data, climate-related impact analysis is poorly understood, and the adaptation strategies studied so far have also been insufficient. This study adopted the most popular DSSAT CERES-Wheat model and the ensemble mean of four GCMs to examine the quantitative effects of adjusted sowing dates and varieties on wheat yield. The two new cultivars (Dandaa and Kakaba), with reference to an old cultivar (Digelu), were considered for the mid-century (2036–2065) and late-century (2066–2095) under RCP 4.5 and RCP 8.5 climate scenarios. The results showed that the Dandaa cultivar demonstrates better adaptation potential at late sowing with a yield increase of about 140 kg/ha to 148 kg/ha for the mid- and late-century under RCP4.5. However, under RCP 8.5, Kakaba demonstrates higher adaptation potential with a yield gain for early sowing of up to 142 kg/ha and 170 kg/ha during the mid- and late-century, respectively. Late sowing of the Dandaa cultivar is recommended if GHG emissions are cut off at least to the average scenario, while the Kakaba cultivar is the best option when the emissions are high. The adaptation measures assessed in this study could help to enhance wheat production and adaptability of wheat to the future climate.

Climate Change Impact Assessment and Adaptation Strategies for Rainfed Wheat in Contrasting Climatic Regions of Iran

This is the first large-scale study to assess the climate change impact on the grain yield of rainfed wheat for three provinces of contrasting climatic conditions (temperate, cold semi-arid, and hot arid) in Iran. Five integrative climate change scenarios including +0.5°C temperature plus−5% precipitation, +1°C plus−10%, +1.5°C plus−15%, +2°C plus−20%, and +2.5°C plus−25% were used and evaluated. Nitrogen fertilizer and shifting planting dates were tested for their suitability as adaptive strategies for rainfed wheat against the changing climate. The climate change scenarios reduced the grain yield by −6.9 to −44.8% in the temperate province Mazandaran and by −7.3 to −54.4% in the hot arid province Khuzestan but increased it by +16.7% in the cold semi-arid province Eastern Azarbaijan. The additional application of +15, +30, +45, and +60 kg ha−1 nitrogen fertilizer as urea at sowing could not, in most cases, compensate for the grain yield reductions under the climate change scenarios. Instead, late planting dates in November, December, and January enhanced the grain yield by +6 to +70.6% in Mazandaran under all climate change scenarios and by +94 to +271% in Khuzestan under all climate change scenarios except under the scenario +2.5°C temperature plus−25% precipitation which led to a grain yield reduction of −85.5%. It is concluded that rainfed wheat production in regions with cold climates can benefit from the climate change, but it can be impaired in temperate regions and especially in vulnerable hot regions like Khuzestan. Shifting planting date can be regarded as an efficient yield-compensating and environmentally friendly adaptive strategy of rainfed wheat against the climate change in temperate and hot arid regions.

Estimating Genetic Parameters for DSSAT CROPGRO-Cotton Model Calibration and Validation

DSSAT CROPGRO-Cotton Model (version 4.7.5) was generally used to forecast the effect of climate change on productivity. The objective of this study was to calibrate and validate this model in Tamil Nadu, India for simulation of development, growth and seed cotton yield of Suraj cotton cultivars under varied planting dates viz., 28th July, 11th August, 18th August, 25th August, 8th September and 15th September. The model was calibrated with data (phenology, biomass and yield components) collected during 2019. Calibration of CROPGRO-Cotton model with genetic coefficients of cultivar Suraj for seed cotton yield (kg ha-1). Simulation of days to flowering, days from planting to first pod and physiological maturity, LAI and seed cotton yield with normalized RMSE (NRMSE) values of less than 10% across all the various planting dates densities were considered excellent. Finally, we discovered that planting at the right time can mitigate many of the negative effects of fluctuating weather on cotton productivity. As a result conclude that DSSAT model will be used to make decision on cotton planting in changing climates.

Calibration and Validation of AQUACROP and APSIM Models to Optimize Wheat Yield and Water Saving in Arid Regions

The APSIM-Wheat and AQUACROP models were calibrated for the Sakha 95 cultivar using phenological data, grain and biomass yield, and genetic parameters based on field observation. Various treatments of planting dates, irrigation, and fertilization were applied over the two successive winter growing seasons of 2019/2020 and 2020/2021. Both models simulated anthesis, maturity dates, grain yield, and aboveground biomass accurately with high performances (coefficient of determination, index of agreement greater than 0.8, and lower values of root mean square deviation) in most cases. The calibrated models were then employed to explore wheat yield and water productivity (WP) in response to irrigation and nitrogen fertilization applications. Scenario analyses indicated that water productivity and yield of wheat ranged from 1.2–2.0 kg m–3 and 6.8–8.7 t ha–1, respectively. Application of 0.8 from actual evapotranspiration and 120% from recommended nitrogen dose was the best-predicted scenario achieving the highest value of crop WP. Investigating the suitable option achieving the current wheat yield by farmers (7.4 t ha–1), models demonstrated that application of 1.4 from actual evapotranspiration with 80% of the recommended nitrogen dose was the best option to achieve this yield. At this point, predicted WP was low and recorded 1.5 kg m–3. Quantifying wheat yield in all districts of the studied area was also predicted using both models. APSIM-Wheat and AQUACROP can be used to drive the best management strategies in terms of N fertilizer and water regime for wheat under Egyptian conditions.