Physiological aspects of sex differences and Haldane’s rule in Rumex hastatulus

Haldane’s rule (HR, impairment of fertility and/or viability of interracial hybrids) seems to be one of few generalizations in evolutionary biology. The validity of HR has been confirmed in animals, and more recently in some dioecious plants (Silene and Rumex). Dioecious Rumex hastatulus has two races differing in the sex chromosome system: Texas (T) and North Carolina (NC), and T × NC males showed both reduced pollen fertility and rarity—two classical symptoms of Haldane’s rule (HR). The reduced fertility of these plants has a simple mechanistic explanation, but the reason for their rarity was not elucidated. Here, we measured selected physiological parameters related to the antioxidant defense system in parental races and reciprocal hybrids of R. hastatulus. We showed that the X-autosome configurations, as well as asymmetries associated with Y chromosomes and cytoplasm, could modulate this system in hybrids. The levels and quantitative patterns of the measured parameters distinguish the T × NC hybrid from the other analyzed forms. Our observations suggest that the rarity of T × NC males is caused postzygotically and most likely related to the higher level of oxidative stress induced by the chromosomal incompatibilities. It is the first report on the physiological aspects of HR in plants

The Effect of Temperature and Precipitation Conditions on the Growth and Development Dynamics of Five Cultivars of Processing Tomato

Cultivation of field tomato in Poland meets unfavorable temperature and precipitation conditions, which affect yield and quality. The aim of the study is to evaluate the effect of temperature and precipitation conditions on the growth and development dynamics of five cultivars of processing tomato. The analysis took into account the key morphological characteristics of the plant, the inflorescence and fruit, which determine the suitability of the cultivar for processing. Analysis of the effect of meteorological elements on the stem development showed that stem length was most strongly influenced by precipitation – both total precipitation and frequency, rather than by temperature; the greater the rainfall, the more intensive stem elongation. High levels of precipitation limited gains in stem thickness. The number of flowers and fruits formed per inflorescence was negatively correlated with temperature. Excessive precipitation during the entire growing period led to formation of smaller fruits. The length and width of the fruit were negatively correlated with the frequency of precipitation in all stages, and with total precipitation during the period from planting to setting of the first fruits. A beneficial effect of temperature on the length and width of the fruit was noted during the entire growing period. The tomato fruit formed a thicker pericarp when precipitation was more frequent