Soybean (Glycine max L.) seedlings may be exposed to low or high temperatures under early or conventional soybean production systems practiced in the US Midsouth. However, a wide range of soybean cultivars commonly grown in the region may inherit diverse tolerance to degrees of temperatures. Therefore, a study was conducted in a controlled-environment facility to quantify 64 soybean cultivars from Maturity Group III to V, to low (LT; 20/12 °C), optimum (OT; 30/22 °C), and high (HT; 40/32 °C) temperature treatments during the seedling growth stage. Several shoot, root, and physiological parameters were assessed at 20 days after sowing. The study found a significant decline in the measured root, shoot, and physiological parameters at both low and high temperatures, except for root average diameter (RAD) and lateral root numbers under LT effects. Under HT, shoot growth was significantly increased, however, root growth showed a significant reduction. Maturity group (MG) III had significantly lower values for the measured root, shoot, and physiological traits across temperature treatments when compared with MG IV and V. Cultivar variability existed and reflected considerably through positive or negative responses in growth to LT and HT. Cumulative stress response indices and principal component analysis were used to identify cultivar-specific tolerance to temperatures. Based on the analysis, cultivars CZ 5225 LL and GS47R216 were identified as most sensitive and tolerant to LT, while, cultivars 45A-46 and 5115LL identified as most tolerant and sensitive to HT, respectively. The information on cultivar-specific tolerance to low or high temperatures obtained in this study would help in cultivar selection to minimize stand loss in present production areas.

Rotylenchulus reniformis Linford and Oliveira (reniform nematode) infestation has been a concerning issue in the Cotton Belt region of the United States for the past decade. Reniform nematode damage is more evident on cotton compared to other row crops in US Mid‐South because they share common edaphic conditions to sustain and develop. Annual cotton (Gossypium spp.) yield loss over the United States due to reniform nematode ranged from 1.14% to 2.37% in the past decade but exceeded 8% in the US Mid‐South States such as Mississippi. Yield losses due to nematode damage are mainly due to inconsistent control by cultural and chemical practices. In addition, there are location‐specific responses due to agronomic practices that result in its wide adaption. This review summarizes factors that influence reniform nematode infestations and the process of a plant infection, as well as management practices to mitigate nematode cotton production losses in the United States. The recent development of resistant cotton germplasm is a promising tool for reniform nematode management, although limited research has been conducted on the physiological mechanisms of resistance. In addition, understanding the role of host plant resistance and the interaction with other soilborne pathogens or abiotic stresses to control the nematode also is lacking. Future research must investigate best suited production practices specific to a region that could exploit the full potential of host plant resistance to minimize the risk of reniform nematode damage in cotton while protecting the environment.

Soil fertility and reniform nematode (RN) directly affect earlyseason growth and physiology of cotton. The growth responses to soil fertility and RN may, however, vary across germplasm. A greenhouse study was conducted to gain information on the role that host plant resistance plays in influencing RN populations, and cotton growth and physiological response to a range of soil nitrogen (N) levels in the presence and absence of RN. RN-resistant cotton lines (08SS110-NE06.OP and 08SS100) along with susceptible cultivars (Deltapine 16 and PHY 490 W3FE) were subjected to four levels of N from planting until biomass harvesting, 60 days after planting(DAP), under the presence orabsence of RN. The linear and quadratic functions (r² = 0.72 to 0.99) bestdescribed measured responses of cotton genotypes to soil N. However, the responses were not different among genotypes, except for plant height at 30 DAP. This study revealed significant increases in several morphological parameters with increasing rates of N. RN population in the pots grown with resistant lines was lower whencompared to susceptible cultivars at biomassharvest. Physiological responses indicated that 08SS110-NE06.OP was more resilient to RN stress than other genotypes. The information from this study could be useful in managing the early season growth of cotton.

The study was carried out at the Indian Agricultural Research Institute, experimental fields (28° N, 77° E) during 2008-2009 and 2009-2010 rabi season to observe response of wheat and chickpea cultivars to reduced levels of solar irradiance. In the present study two wheat ( Triticum aestivum; HD 2643 and PBW 343) and two chickpea (Cicer arienitum L. ; BG 1105 and BGD 72) cultivars were subjectedto 20 per cent and 35 per cent less levels of solar irradiance than the control that received 100 per cent natural sunlight during entire crop growth period. The results show that the height and leaf area index (LAI) of both the crops cultivars under reduced solar irradiance were more than natural light. Under reduced solar irradiance, height of wheat cultivar HD 2643 was more than PBW 343 and that of chickpea cultivar BG 1105 was more than BGD 72. Reduction in solar irradiance affected the photosynthesis and stomatal conductance process in both the crops. About 4-29 per cent reduction in rate of photosynthesis in wheat and chickpea varieties was observed under reduced levels of solar irradiance. Reduction in stomatal conductance under reduced levels of solar irradiance in wheat varieties was 6-28 per cent and in chickpea varieties it was 1-14 per cent. Biological yield of wheat and chickpea varieties was decreased by about 37-45 per cent and 13-53 per cent respectively, under reduced levels of solar irradiance. Observations show that among wheat cultivars PBW 343 was less affected by reduced levels of solar irradiance than HD 2643. Among chickpea cultivars BGD 72 was less affected by reduced levels of solar irradiance than BG 1105. The PBW 343 and BGD 72 cultivars of wheat and chickpea may be used by breeders to develop new varieties to increase agricultural production in climatic condition subjected to low irradiance.