Early planting of corn (Zea mays L.) is a strategy to avoid excessive heat and drought that often negatively influence grain production during its reproductive phase. An experiment was conducted by imposing very low (day/night, 21/13°C), low (25/17°C), and optimum (29/21°C) temperatures during seed germination and seedling growth stages under optimum moisture and nutrient conditions. Above‐ and belowground growth parameters were assessed at 18 d after seeding. Several root morphological traits were assessed using the WinRHIZO root image analysis system. Corn hybrids varied significantly for many traits measured, particularly plant component weights and root morphological parameters. Principal component analysis (PCA) and total low‐temperature response index (TLTRI) methods were used to categorize corn hybrid tolerance to low temperature and to group corn hybrids as cold tolerant, moderately cold tolerant, moderately cold sensitive, and cold sensitive. Total leaf and root weights and cumulative root length and length per unit volume were the most important morphological traits in describing hybrid tolerance to cold temperature. Based on the TLTRI method, relative scores were provided for each hybrid, which ranged from 22.45 to 29.52 among the hybrids. The hybrids CR8410VT3P, D57VP51, and R22BHR43 were classified as cold sensitive and AR1262, DKC6697, DKC6804, and M2V707 as cold tolerant based on PCA and TLTRI techniques. Based on the relative scores assigned in this study, corn producers could select hybrids to maximize corn production in an early planting production system.

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Little insight of temperature effects on cotton root morphology and seed germination. Cotton cultivars vary in their response to different temperatures. Growth and developmental responses developed will be useful in cotton crop models. Establishing vigorous cotton (Gossypium hirsutum L.) seedling stand for an early planted crop will help to develop healthy root and canopy development. Cotton planted early in the season will be subjected to low, but variable temperatures and soil moisture conditions. There has been little exploration of temperature effects on the cotton root system architecture. The objective of this study was to study the effects of a wide range of temperatures during seed germination and early seedling growth stages on above‐ and belowground growth and developmental parameters of four cotton cultivars. A molecular standard, Texas Marker (TM)‐1 and three modern cotton cultivars (DP1522B2XF, PHY496W3R, and ST4747GLB2) were sown at five day/night temperature regimes of 20/12, 25/17, 30/22, 35/27, and 40/32 °C (day/night). Shoot and root growth parameters were measured 20 days after planting (DAP). The small differences observed between the obsolete molecular standard, TM‐1, and the three modern cultivars in response to temperature indicate that successive breeding efforts did not change the rate or behavior of these traits to temperature. Seedling emergence was best described by both linear (TM‐1 and PHY496W3R) and quadratic (DP1522 B2XF, and ST4747 GLB2) functions. Node numbers and root tips increased linearly with increase in temperature, and no cultivar differences were observed for this trait. The functional relationships between temperature and cotton seed emergence and pre‐squaring above‐ and belowground growth and developmental responses will be useful in assisting management and in improving functionality of many cotton models for on‐farm and research and policy decisions.

Drought is one of the major abiotic stresses that limit soybean production worldwide. This study was conducted to determine whether soybean cultivars with divergent growth habits respond differently to drought stress at the vegetative growth stage regarding canopy reflectance, physiological, and gas exchange traits under controlled conditions. Soil moisture content was positively correlated with midday leaf water potential. Pooled over cultivar, photosynthesis and stomatal conductance were highly correlated with midday leaf water potential, while Ci/Ca exhibited a weak positive correlation. These data indicate that, regardless of cultivar, the decrease in net photosynthesis is mainly due to stomatal closure. For both cultivars, drought stress increased soybean canopy reflectance in the visible range of the spectrum but decreased reflectance in the near-infrared region. The quantified physiological traits would be useful to understand plant water relations and canopy structure to help soybean growers to make field management decisions during the growing season.

Effects of environmental stressors on the parent may be transmitted to the F1 generation of plants that support global food, oil, and energy production for humans and animals. This study was conducted to determine if the effects of drought stress on parental soybean plants are transmitted to the F1 generation. The germination and seedling vigor of F1 soybean whose maternal parents, Asgrow AG5332 and Progeny P5333RY, were exposed to soil moisture stress, that is, 100, 80, 60, 40, and 20% replacement of evapotranspiration (ET) during reproductive growth, were evaluated under controlled conditions. Pooled over cultivars, effects of soil moisture stress on the parents caused a reduction in the seed germination rate, maximum seed germination, and overall seedling performance in the F1 generation. The effect of soil moisture stress on the parent environment induced seed quality that carried on the F1 generation seed gemination and seedling traits under optimum conditions and further exasperated when exposed to increasing levels of drought stress. Results indicate that seed weight and storage reserve are key factors positively associated with germination traits and seedling growth. Our data confirm that the effects of soil moisture stress on soybean are transferable, causing reduced germination, seedling vigor, and seed quality in the F1 generation. Therefore, optimal water supply during soybean seed formation period may be beneficial for seed producers in terms of optimizing seed quality and vigor characteristics of commodity seed.